refactor(transcoding): rename TranscodeDecision to Decider and update related methods for clarity

Signed-off-by: Deluan <deluan@navidrome.org>

.dockerignore

@@ -15,4 +15,5 @@ dist
 binaries
 cache
 music
+music.old
 !Dockerfile

.gitignore

@@ -20,6 +20,7 @@ cache/*
 coverage.out
 dist
 music
+music.old
 *.db*
 .gitinfo
 docker-compose.yml

adapters/gotaglib/gotaglib.go

@@ -64,6 +64,7 @@ func (e extractor) extractMetadata(filePath string) (*metadata.Info, error) {
 		Channels:   int(props.Channels),
 		SampleRate: int(props.SampleRate),
 		BitDepth:   int(props.BitsPerSample),
+		Codec:      props.Codec,
 	}
 
 	// Convert normalized tags to lowercase keys (go-taglib returns UPPERCASE keys)

adapters/lastfm/agent.go

@@ -31,6 +31,12 @@ var ignoredContent = []string{
 	`<a href="https://www.last.fm/music/`,
 }
 
+var lastFMReadMoreRegex = regexp.MustCompile(`\s*<a href="https://www\.last\.fm/music/[^"]*">Read more on Last\.fm</a>\.?`)
+
+func cleanContent(content string) string {
+	return strings.TrimSpace(lastFMReadMoreRegex.ReplaceAllString(content, ""))
+}
+
 type lastfmAgent struct {
 	ds           model.DataStore
 	sessionKeys  *agents.SessionKeys
@@ -95,7 +101,7 @@ func (l *lastfmAgent) GetAlbumInfo(ctx context.Context, name, artist, mbid strin
 		resp.MBID = a.MBID
 		resp.URL = a.URL
 		if isValidContent(a.Description.Summary) {
-			resp.Description = strings.TrimSpace(a.Description.Summary)
+			resp.Description = cleanContent(a.Description.Summary)
 			return &resp, nil
 		}
 		log.Debug(ctx, "LastFM/album.getInfo returned empty/ignored description, trying next language", "album", name, "artist", artist, "lang", lang)
@@ -171,7 +177,7 @@ func (l *lastfmAgent) GetArtistBiography(ctx context.Context, id, name, mbid str
 			return "", err
 		}
 		if isValidContent(a.Bio.Summary) {
-			return strings.TrimSpace(a.Bio.Summary), nil
+			return cleanContent(a.Bio.Summary), nil
 		}
 		log.Debug(ctx, "LastFM/artist.getInfo returned empty/ignored biography, trying next language", "artist", name, "lang", lang)
 	}

adapters/lastfm/agent_test.go

@@ -80,7 +80,7 @@ var _ = Describe("lastfmAgent", func() {
 		It("returns the biography", func() {
 			f, _ := os.Open("tests/fixtures/lastfm.artist.getinfo.json")
 			httpClient.Res = http.Response{Body: f, StatusCode: 200}
-			Expect(agent.GetArtistBiography(ctx, "123", "U2", "")).To(Equal("U2 é uma das mais importantes bandas de rock de todos os tempos. Formada em 1976 em Dublin, composta por Bono (vocalista  e guitarrista), The Edge (guitarrista, pianista e backing vocal), Adam Clayton (baixista), Larry Mullen, Jr. (baterista e percussionista).\n\nDesde a década de 80, U2 é uma das bandas mais populares no mundo. Seus shows são únicos e um verdadeiro festival de efeitos especiais, além de serem um dos que mais arrecadam anualmente. <a href=\"https://www.last.fm/music/U2\">Read more on Last.fm</a>"))
+			Expect(agent.GetArtistBiography(ctx, "123", "U2", "")).To(Equal("U2 é uma das mais importantes bandas de rock de todos os tempos. Formada em 1976 em Dublin, composta por Bono (vocalista  e guitarrista), The Edge (guitarrista, pianista e backing vocal), Adam Clayton (baixista), Larry Mullen, Jr. (baterista e percussionista).\n\nDesde a década de 80, U2 é uma das bandas mais populares no mundo. Seus shows são únicos e um verdadeiro festival de efeitos especiais, além de serem um dos que mais arrecadam anualmente."))
 			Expect(httpClient.RequestCount).To(Equal(1))
 			Expect(httpClient.SavedRequest.URL.Query().Get("artist")).To(Equal("U2"))
 		})
@@ -535,7 +535,7 @@ var _ = Describe("lastfmAgent", func() {
 			Expect(agent.GetAlbumInfo(ctx, "Believe", "Cher", "03c91c40-49a6-44a7-90e7-a700edf97a62")).To(Equal(&agents.AlbumInfo{
 				Name:        "Believe",
 				MBID:        "03c91c40-49a6-44a7-90e7-a700edf97a62",
-				Description: "Believe is the twenty-third studio album by American singer-actress Cher, released on November 10, 1998 by Warner Bros. Records. The RIAA certified it Quadruple Platinum on December 23, 1999, recognizing four million shipments in the United States; Worldwide, the album has sold more than 20 million copies, making it the biggest-selling album of her career. In 1999 the album received three Grammy Awards nominations including \"Record of the Year\", \"Best Pop Album\" and winning \"Best Dance Recording\" for the single \"Believe\". It was released by Warner Bros. Records at the end of 1998. The album was executive produced by Rob <a href=\"https://www.last.fm/music/Cher/Believe\">Read more on Last.fm</a>.",
+				Description: "Believe is the twenty-third studio album by American singer-actress Cher, released on November 10, 1998 by Warner Bros. Records. The RIAA certified it Quadruple Platinum on December 23, 1999, recognizing four million shipments in the United States; Worldwide, the album has sold more than 20 million copies, making it the biggest-selling album of her career. In 1999 the album received three Grammy Awards nominations including \"Record of the Year\", \"Best Pop Album\" and winning \"Best Dance Recording\" for the single \"Believe\". It was released by Warner Bros. Records at the end of 1998. The album was executive produced by Rob",
 				URL:         "https://www.last.fm/music/Cher/Believe",
 			}))
 			Expect(httpClient.RequestCount).To(Equal(1))

cmd/wire_gen.go

@@ -19,6 +19,7 @@ import (
 	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/core/playback"
 	"github.com/navidrome/navidrome/core/scrobbler"
+	"github.com/navidrome/navidrome/core/transcode"
 	"github.com/navidrome/navidrome/db"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/persistence"
@@ -102,7 +103,8 @@ func CreateSubsonicAPIRouter(ctx context.Context) *subsonic.Router {
 	modelScanner := scanner.New(ctx, dataStore, cacheWarmer, broker, playlists, metricsMetrics)
 	playTracker := scrobbler.GetPlayTracker(dataStore, broker, manager)
 	playbackServer := playback.GetInstance(dataStore)
-	router := subsonic.New(dataStore, artworkArtwork, mediaStreamer, archiver, players, provider, modelScanner, broker, playlists, playTracker, share, playbackServer, metricsMetrics)
+	decider := transcode.NewDecider(dataStore)
+	router := subsonic.New(dataStore, artworkArtwork, mediaStreamer, archiver, players, provider, modelScanner, broker, playlists, playTracker, share, playbackServer, metricsMetrics, decider)
 	return router
 }
 

core/transcode/transcode.go

@@ -0,0 +1,689 @@
+package transcode
+
+import (
+	"context"
+	"slices"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/navidrome/navidrome/core/auth"
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/model"
+)
+
+const (
+	tokenTTL       = 12 * time.Hour
+	defaultBitrate = 256 // kbps
+)
+
+// Decider is the core service interface for making transcoding decisions
+type Decider interface {
+	MakeDecision(ctx context.Context, mf *model.MediaFile, clientInfo *ClientInfo) (*Decision, error)
+	CreateTranscodeParams(decision *Decision) (string, error)
+	ParseTranscodeParams(token string) (*Params, error)
+}
+
+// ClientInfo represents client playback capabilities.
+// All bitrate values are in kilobits per second (kbps)
+type ClientInfo struct {
+	Name                       string
+	Platform                   string
+	MaxAudioBitrate            int
+	MaxTranscodingAudioBitrate int
+	DirectPlayProfiles         []DirectPlayProfile
+	TranscodingProfiles        []Profile
+	CodecProfiles              []CodecProfile
+}
+
+// DirectPlayProfile describes a format the client can play directly
+type DirectPlayProfile struct {
+	Containers       []string
+	AudioCodecs      []string
+	Protocols        []string
+	MaxAudioChannels int
+}
+
+// Profile describes a transcoding target the client supports
+type Profile struct {
+	Container        string
+	AudioCodec       string
+	Protocol         string
+	MaxAudioChannels int
+}
+
+// CodecProfile describes codec-specific limitations
+type CodecProfile struct {
+	Type        string
+	Name        string
+	Limitations []Limitation
+}
+
+// Limitation describes a specific codec limitation
+type Limitation struct {
+	Name       string
+	Comparison string
+	Values     []string
+	Required   bool
+}
+
+// Protocol values (OpenSubsonic spec enum)
+const (
+	ProtocolHTTP = "http"
+	ProtocolHLS  = "hls"
+)
+
+// Comparison operators (OpenSubsonic spec enum)
+const (
+	ComparisonEquals           = "Equals"
+	ComparisonNotEquals        = "NotEquals"
+	ComparisonLessThanEqual    = "LessThanEqual"
+	ComparisonGreaterThanEqual = "GreaterThanEqual"
+)
+
+// Limitation names (OpenSubsonic spec enum)
+const (
+	LimitationAudioChannels   = "audioChannels"
+	LimitationAudioBitrate    = "audioBitrate"
+	LimitationAudioProfile    = "audioProfile"
+	LimitationAudioSamplerate = "audioSamplerate"
+	LimitationAudioBitdepth   = "audioBitdepth"
+)
+
+// Codec profile types (OpenSubsonic spec enum)
+const (
+	CodecProfileTypeAudio = "AudioCodec"
+)
+
+// Decision represents the internal decision result.
+// All bitrate values are in kilobits per second (kbps).
+type Decision struct {
+	MediaID          string
+	CanDirectPlay    bool
+	CanTranscode     bool
+	TranscodeReasons []string
+	ErrorReason      string
+	TargetFormat     string
+	TargetBitrate    int
+	TargetChannels   int
+	SourceStream     StreamDetails
+	TranscodeStream  *StreamDetails
+}
+
+// StreamDetails describes audio stream properties.
+// Bitrate is in kilobits per second (kbps).
+type StreamDetails struct {
+	Container  string
+	Codec      string
+	Profile    string // Audio profile (e.g., "LC", "HE-AAC"). Empty until scanner support is added.
+	Bitrate    int
+	SampleRate int
+	BitDepth   int
+	Channels   int
+	Duration   float32
+	Size       int64
+	IsLossless bool
+}
+
+// Params contains the parameters extracted from a transcode token.
+// TargetBitrate is in kilobits per second (kbps).
+type Params struct {
+	MediaID        string
+	DirectPlay     bool
+	TargetFormat   string
+	TargetBitrate  int
+	TargetChannels int
+}
+
+func NewDecider(ds model.DataStore) Decider {
+	return &deciderService{
+		ds: ds,
+	}
+}
+
+type deciderService struct {
+	ds model.DataStore
+}
+
+func (s *deciderService) MakeDecision(ctx context.Context, mf *model.MediaFile, clientInfo *ClientInfo) (*Decision, error) {
+	decision := &Decision{
+		MediaID: mf.ID,
+	}
+
+	sourceBitrate := mf.BitRate // kbps
+
+	log.Trace(ctx, "Making transcode decision", "mediaID", mf.ID, "container", mf.Suffix,
+		"codec", mf.AudioCodec(), "bitrate", sourceBitrate, "channels", mf.Channels,
+		"sampleRate", mf.SampleRate, "lossless", mf.IsLossless(), "client", clientInfo.Name)
+
+	// Build source stream details
+	decision.SourceStream = StreamDetails{
+		Container:  mf.Suffix,
+		Codec:      mf.AudioCodec(),
+		Bitrate:    sourceBitrate,
+		SampleRate: mf.SampleRate,
+		BitDepth:   mf.BitDepth,
+		Channels:   mf.Channels,
+		Duration:   mf.Duration,
+		Size:       mf.Size,
+		IsLossless: mf.IsLossless(),
+	}
+
+	// Check global bitrate constraint first.
+	if clientInfo.MaxAudioBitrate > 0 && sourceBitrate > clientInfo.MaxAudioBitrate {
+		log.Trace(ctx, "Global bitrate constraint exceeded, skipping direct play",
+			"sourceBitrate", sourceBitrate, "maxAudioBitrate", clientInfo.MaxAudioBitrate)
+		decision.TranscodeReasons = append(decision.TranscodeReasons, "audio bitrate not supported")
+		// Skip direct play profiles entirely — global constraint fails
+	} else {
+		// Try direct play profiles, collecting reasons for each failure
+		for _, profile := range clientInfo.DirectPlayProfiles {
+			if reason := s.checkDirectPlayProfile(mf, sourceBitrate, &profile, clientInfo); reason == "" {
+				decision.CanDirectPlay = true
+				decision.TranscodeReasons = nil // Clear any previously collected reasons
+				break
+			} else {
+				decision.TranscodeReasons = append(decision.TranscodeReasons, reason)
+			}
+		}
+	}
+
+	// If direct play is possible, we're done
+	if decision.CanDirectPlay {
+		log.Debug(ctx, "Transcode decision: direct play", "mediaID", mf.ID, "container", mf.Suffix, "codec", mf.AudioCodec())
+		return decision, nil
+	}
+
+	// Try transcoding profiles (in order of preference)
+	for _, profile := range clientInfo.TranscodingProfiles {
+		if ts := s.computeTranscodedStream(ctx, mf, sourceBitrate, &profile, clientInfo); ts != nil {
+			decision.CanTranscode = true
+			decision.TargetFormat = ts.Container
+			decision.TargetBitrate = ts.Bitrate
+			decision.TargetChannels = ts.Channels
+			decision.TranscodeStream = ts
+			break
+		}
+	}
+
+	if decision.CanTranscode {
+		log.Debug(ctx, "Transcode decision: transcode", "mediaID", mf.ID,
+			"targetFormat", decision.TargetFormat, "targetBitrate", decision.TargetBitrate,
+			"targetChannels", decision.TargetChannels, "reasons", decision.TranscodeReasons)
+	}
+
+	// If neither direct play nor transcode is possible
+	if !decision.CanDirectPlay && !decision.CanTranscode {
+		decision.ErrorReason = "no compatible playback profile found"
+		log.Warn(ctx, "Transcode decision: no compatible profile", "mediaID", mf.ID,
+			"container", mf.Suffix, "codec", mf.AudioCodec(), "reasons", decision.TranscodeReasons)
+	}
+
+	return decision, nil
+}
+
+// checkDirectPlayProfile returns "" if the profile matches (direct play OK),
+// or a typed reason string if it doesn't match.
+func (s *deciderService) checkDirectPlayProfile(mf *model.MediaFile, sourceBitrate int, profile *DirectPlayProfile, clientInfo *ClientInfo) string {
+	// Check protocol (only http for now)
+	if len(profile.Protocols) > 0 && !containsIgnoreCase(profile.Protocols, ProtocolHTTP) {
+		return "protocol not supported"
+	}
+
+	// Check container
+	if len(profile.Containers) > 0 && !matchesContainer(mf.Suffix, profile.Containers) {
+		return "container not supported"
+	}
+
+	// Check codec
+	if len(profile.AudioCodecs) > 0 && !matchesCodec(mf.AudioCodec(), profile.AudioCodecs) {
+		return "audio codec not supported"
+	}
+
+	// Check channels
+	if profile.MaxAudioChannels > 0 && mf.Channels > profile.MaxAudioChannels {
+		return "audio channels not supported"
+	}
+
+	// Check codec-specific limitations
+	for _, codecProfile := range clientInfo.CodecProfiles {
+		if strings.EqualFold(codecProfile.Type, CodecProfileTypeAudio) && matchesCodec(mf.AudioCodec(), []string{codecProfile.Name}) {
+			if reason := checkLimitations(mf, sourceBitrate, codecProfile.Limitations); reason != "" {
+				return reason
+			}
+		}
+	}
+
+	return ""
+}
+
+// checkLimitations checks codec profile limitations against source media.
+// Returns "" if all limitations pass, or a typed reason string for the first failure.
+func checkLimitations(mf *model.MediaFile, sourceBitrate int, limitations []Limitation) string {
+	for _, lim := range limitations {
+		var ok bool
+		var reason string
+
+		switch lim.Name {
+		case LimitationAudioChannels:
+			ok = checkIntLimitation(mf.Channels, lim.Comparison, lim.Values)
+			reason = "audio channels not supported"
+		case LimitationAudioSamplerate:
+			ok = checkIntLimitation(mf.SampleRate, lim.Comparison, lim.Values)
+			reason = "audio samplerate not supported"
+		case LimitationAudioBitrate:
+			ok = checkIntLimitation(sourceBitrate, lim.Comparison, lim.Values)
+			reason = "audio bitrate not supported"
+		case LimitationAudioBitdepth:
+			ok = checkIntLimitation(mf.BitDepth, lim.Comparison, lim.Values)
+			reason = "audio bitdepth not supported"
+		case LimitationAudioProfile:
+			// TODO: populate source profile when MediaFile has audio profile info
+			ok = checkStringLimitation("", lim.Comparison, lim.Values)
+			reason = "audio profile not supported"
+		default:
+			continue
+		}
+
+		if !ok && lim.Required {
+			return reason
+		}
+	}
+	return ""
+}
+
+// adjustResult represents the outcome of applying a limitation to a transcoded stream value
+type adjustResult int
+
+const (
+	adjustNone      adjustResult = iota // Value already satisfies the limitation
+	adjustAdjusted                      // Value was changed to fit the limitation
+	adjustCannotFit                     // Cannot satisfy the limitation (reject this profile)
+)
+
+// computeTranscodedStream attempts to build a valid transcoded stream for the given profile.
+// Returns nil if the profile cannot produce a valid output.
+func (s *deciderService) computeTranscodedStream(ctx context.Context, mf *model.MediaFile, sourceBitrate int, profile *Profile, clientInfo *ClientInfo) *StreamDetails {
+	// Check protocol (only http for now)
+	if profile.Protocol != "" && !strings.EqualFold(profile.Protocol, ProtocolHTTP) {
+		log.Trace(ctx, "Skipping transcoding profile: unsupported protocol", "protocol", profile.Protocol)
+		return nil
+	}
+
+	targetFormat := strings.ToLower(profile.Container)
+	if targetFormat == "" {
+		targetFormat = strings.ToLower(profile.AudioCodec)
+	}
+
+	// Verify we have a transcoding config for this format
+	tc, err := s.ds.Transcoding(ctx).FindByFormat(targetFormat)
+	if err != nil || tc == nil {
+		log.Trace(ctx, "Skipping transcoding profile: no transcoding config", "targetFormat", targetFormat)
+		return nil
+	}
+
+	targetIsLossless := isLosslessFormat(targetFormat)
+
+	// Reject lossy to lossless conversion
+	if !mf.IsLossless() && targetIsLossless {
+		log.Trace(ctx, "Skipping transcoding profile: lossy to lossless not allowed", "targetFormat", targetFormat)
+		return nil
+	}
+
+	ts := &StreamDetails{
+		Container:  targetFormat,
+		Codec:      strings.ToLower(profile.AudioCodec),
+		SampleRate: mf.SampleRate,
+		Channels:   mf.Channels,
+		IsLossless: targetIsLossless,
+	}
+	if ts.Codec == "" {
+		ts.Codec = targetFormat
+	}
+
+	// Determine target bitrate (all in kbps)
+	if mf.IsLossless() {
+		if !targetIsLossless {
+			// Lossless to lossy: use client's max transcoding bitrate or default
+			if clientInfo.MaxTranscodingAudioBitrate > 0 {
+				ts.Bitrate = clientInfo.MaxTranscodingAudioBitrate
+			} else {
+				ts.Bitrate = defaultBitrate
+			}
+		} else {
+			// Lossless to lossless: check if bitrate is under the global max
+			if clientInfo.MaxAudioBitrate > 0 && sourceBitrate > clientInfo.MaxAudioBitrate {
+				log.Trace(ctx, "Skipping transcoding profile: lossless target exceeds bitrate limit",
+					"targetFormat", targetFormat, "sourceBitrate", sourceBitrate, "maxAudioBitrate", clientInfo.MaxAudioBitrate)
+				return nil
+			}
+			// No explicit bitrate for lossless target (leave 0)
+		}
+	} else {
+		// Lossy to lossy: preserve source bitrate
+		ts.Bitrate = sourceBitrate
+	}
+
+	// Apply maxAudioBitrate as final cap on transcoded stream (#5)
+	if clientInfo.MaxAudioBitrate > 0 && ts.Bitrate > 0 && ts.Bitrate > clientInfo.MaxAudioBitrate {
+		ts.Bitrate = clientInfo.MaxAudioBitrate
+	}
+
+	// Apply MaxAudioChannels from the transcoding profile
+	if profile.MaxAudioChannels > 0 && mf.Channels > profile.MaxAudioChannels {
+		ts.Channels = profile.MaxAudioChannels
+	}
+
+	// Apply codec profile limitations to the TARGET codec (#4)
+	targetCodec := ts.Codec
+	for _, codecProfile := range clientInfo.CodecProfiles {
+		if !strings.EqualFold(codecProfile.Type, CodecProfileTypeAudio) {
+			continue
+		}
+		if !matchesCodec(targetCodec, []string{codecProfile.Name}) {
+			continue
+		}
+		for _, lim := range codecProfile.Limitations {
+			result := applyLimitation(sourceBitrate, &lim, ts)
+			// For lossless codecs, adjusting bitrate is not valid
+			if strings.EqualFold(lim.Name, LimitationAudioBitrate) && targetIsLossless && result == adjustAdjusted {
+				log.Trace(ctx, "Skipping transcoding profile: cannot adjust bitrate for lossless target",
+					"targetFormat", targetFormat, "codec", targetCodec, "limitation", lim.Name)
+				return nil
+			}
+			if result == adjustCannotFit {
+				log.Trace(ctx, "Skipping transcoding profile: codec limitation cannot be satisfied",
+					"targetFormat", targetFormat, "codec", targetCodec, "limitation", lim.Name,
+					"comparison", lim.Comparison, "values", lim.Values)
+				return nil
+			}
+		}
+	}
+
+	return ts
+}
+
+// applyLimitation adjusts a transcoded stream parameter to satisfy the limitation.
+// Returns the adjustment result.
+func applyLimitation(sourceBitrate int, lim *Limitation, ts *StreamDetails) adjustResult {
+	switch lim.Name {
+	case LimitationAudioChannels:
+		return applyIntLimitation(lim.Comparison, lim.Values, ts.Channels, func(v int) { ts.Channels = v })
+	case LimitationAudioBitrate:
+		current := ts.Bitrate
+		if current == 0 {
+			current = sourceBitrate
+		}
+		return applyIntLimitation(lim.Comparison, lim.Values, current, func(v int) { ts.Bitrate = v })
+	case LimitationAudioSamplerate:
+		return applyIntLimitation(lim.Comparison, lim.Values, ts.SampleRate, func(v int) { ts.SampleRate = v })
+	case LimitationAudioBitdepth:
+		if ts.BitDepth > 0 {
+			return applyIntLimitation(lim.Comparison, lim.Values, ts.BitDepth, func(v int) { ts.BitDepth = v })
+		}
+	case LimitationAudioProfile:
+		// TODO: implement when audio profile data is available
+	}
+	return adjustNone
+}
+
+// applyIntLimitation applies a limitation comparison to a value.
+// If the value needs adjusting, calls the setter and returns the result.
+func applyIntLimitation(comparison string, values []string, current int, setter func(int)) adjustResult {
+	if len(values) == 0 {
+		return adjustNone
+	}
+
+	switch comparison {
+	case ComparisonLessThanEqual:
+		limit, ok := parseInt(values[0])
+		if !ok {
+			return adjustNone
+		}
+		if current <= limit {
+			return adjustNone
+		}
+		setter(limit)
+		return adjustAdjusted
+	case ComparisonGreaterThanEqual:
+		limit, ok := parseInt(values[0])
+		if !ok {
+			return adjustNone
+		}
+		if current >= limit {
+			return adjustNone
+		}
+		// Cannot upscale
+		return adjustCannotFit
+	case ComparisonEquals:
+		// Check if current value matches any allowed value
+		for _, v := range values {
+			if limit, ok := parseInt(v); ok && current == limit {
+				return adjustNone
+			}
+		}
+		// Find the closest allowed value below current (don't upscale)
+		var closest int
+		found := false
+		for _, v := range values {
+			if limit, ok := parseInt(v); ok && limit < current {
+				if !found || limit > closest {
+					closest = limit
+					found = true
+				}
+			}
+		}
+		if found {
+			setter(closest)
+			return adjustAdjusted
+		}
+		return adjustCannotFit
+	case ComparisonNotEquals:
+		for _, v := range values {
+			if limit, ok := parseInt(v); ok && current == limit {
+				return adjustCannotFit
+			}
+		}
+		return adjustNone
+	}
+
+	return adjustNone
+}
+
+func (s *deciderService) CreateTranscodeParams(decision *Decision) (string, error) {
+	exp := time.Now().Add(tokenTTL)
+	claims := map[string]any{
+		"mid": decision.MediaID,
+		"dp":  decision.CanDirectPlay,
+	}
+	if decision.CanTranscode && decision.TargetFormat != "" {
+		claims["fmt"] = decision.TargetFormat
+		claims["br"] = decision.TargetBitrate
+		if decision.TargetChannels > 0 {
+			claims["ch"] = decision.TargetChannels
+		}
+	}
+	return auth.CreateExpiringPublicToken(exp, claims)
+}
+
+func (s *deciderService) ParseTranscodeParams(token string) (*Params, error) {
+	claims, err := auth.Validate(token)
+	if err != nil {
+		return nil, err
+	}
+
+	params := &Params{}
+	if mid, ok := claims["mid"].(string); ok {
+		params.MediaID = mid
+	}
+	if dp, ok := claims["dp"].(bool); ok {
+		params.DirectPlay = dp
+	}
+	if fmt, ok := claims["fmt"].(string); ok {
+		params.TargetFormat = fmt
+	}
+	if br, ok := claims["br"].(float64); ok {
+		params.TargetBitrate = int(br)
+	}
+	if ch, ok := claims["ch"].(float64); ok {
+		params.TargetChannels = int(ch)
+	}
+
+	return params, nil
+}
+
+func containsIgnoreCase(slice []string, s string) bool {
+	return slices.ContainsFunc(slice, func(item string) bool {
+		return strings.EqualFold(item, s)
+	})
+}
+
+// containerAliasGroups maps each container alias to a canonical group name.
+var containerAliasGroups = func() map[string]string {
+	groups := [][]string{
+		{"aac", "adts", "m4a", "mp4", "m4b", "m4p"},
+		{"mpeg", "mp3", "mp2"},
+		{"ogg", "oga"},
+		{"aif", "aiff"},
+		{"asf", "wma"},
+		{"mpc", "mpp"},
+		{"wv"},
+	}
+	m := make(map[string]string)
+	for _, g := range groups {
+		canonical := g[0]
+		for _, name := range g {
+			m[name] = canonical
+		}
+	}
+	return m
+}()
+
+// matchesWithAliases checks if a value matches any entry in candidates,
+// consulting the alias map for equivalent names.
+func matchesWithAliases(value string, candidates []string, aliases map[string]string) bool {
+	value = strings.ToLower(value)
+	canonical := aliases[value]
+	for _, c := range candidates {
+		c = strings.ToLower(c)
+		if c == value {
+			return true
+		}
+		if canonical != "" && aliases[c] == canonical {
+			return true
+		}
+	}
+	return false
+}
+
+// matchesContainer checks if a file suffix matches any of the container names,
+// including common aliases.
+func matchesContainer(suffix string, containers []string) bool {
+	return matchesWithAliases(suffix, containers, containerAliasGroups)
+}
+
+// codecAliasGroups maps each codec alias to a canonical group name.
+// Codecs within the same group are considered equivalent.
+var codecAliasGroups = func() map[string]string {
+	groups := [][]string{
+		{"aac", "adts"},
+		{"ac3", "ac-3"},
+		{"eac3", "e-ac3", "e-ac-3", "eac-3"},
+		{"mpc7", "musepack7"},
+		{"mpc8", "musepack8"},
+		{"wma1", "wmav1"},
+		{"wma2", "wmav2"},
+		{"wmalossless", "wma9lossless"},
+		{"wmapro", "wma9pro"},
+		{"shn", "shorten"},
+		{"mp4als", "als"},
+	}
+	m := make(map[string]string)
+	for _, g := range groups {
+		for _, name := range g {
+			m[name] = g[0] // canonical = first entry
+		}
+	}
+	return m
+}()
+
+// matchesCodec checks if a codec matches any of the codec names,
+// including common aliases.
+func matchesCodec(codec string, codecs []string) bool {
+	return matchesWithAliases(codec, codecs, codecAliasGroups)
+}
+
+func checkIntLimitation(value int, comparison string, values []string) bool {
+	if len(values) == 0 {
+		return true
+	}
+
+	switch comparison {
+	case ComparisonLessThanEqual:
+		limit, ok := parseInt(values[0])
+		if !ok {
+			return true
+		}
+		return value <= limit
+	case ComparisonGreaterThanEqual:
+		limit, ok := parseInt(values[0])
+		if !ok {
+			return true
+		}
+		return value >= limit
+	case ComparisonEquals:
+		for _, v := range values {
+			if limit, ok := parseInt(v); ok && value == limit {
+				return true
+			}
+		}
+		return false
+	case ComparisonNotEquals:
+		for _, v := range values {
+			if limit, ok := parseInt(v); ok && value == limit {
+				return false
+			}
+		}
+		return true
+	}
+	return true
+}
+
+// checkStringLimitation checks a string value against a limitation.
+// Only Equals and NotEquals comparisons are meaningful for strings.
+// LessThanEqual/GreaterThanEqual are not applicable and always pass.
+func checkStringLimitation(value string, comparison string, values []string) bool {
+	switch comparison {
+	case ComparisonEquals:
+		for _, v := range values {
+			if strings.EqualFold(value, v) {
+				return true
+			}
+		}
+		return false
+	case ComparisonNotEquals:
+		for _, v := range values {
+			if strings.EqualFold(value, v) {
+				return false
+			}
+		}
+		return true
+	}
+	return true
+}
+
+func parseInt(s string) (int, bool) {
+	v, err := strconv.Atoi(s)
+	if err != nil || v < 0 {
+		return 0, false
+	}
+	return v, true
+}
+
+func isLosslessFormat(format string) bool {
+	switch strings.ToLower(format) {
+	case "flac", "alac", "wav", "aiff", "ape", "wv", "tta", "tak", "shn", "dsd":
+		return true
+	}
+	return false
+}

core/transcode/transcode_suite_test.go

@@ -0,0 +1,17 @@
+package transcode
+
+import (
+	"testing"
+
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/tests"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestTranscode(t *testing.T) {
+	tests.Init(t, false)
+	log.SetLevel(log.LevelFatal)
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Transcode Suite")
+}

core/transcode/transcode_test.go

@@ -0,0 +1,657 @@
+package transcode
+
+import (
+	"context"
+
+	"github.com/navidrome/navidrome/core/auth"
+	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/tests"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Decider", func() {
+	var (
+		ds  *tests.MockDataStore
+		svc Decider
+		ctx context.Context
+	)
+
+	BeforeEach(func() {
+		ctx = context.Background()
+		ds = &tests.MockDataStore{
+			MockedProperty:    &tests.MockedPropertyRepo{},
+			MockedTranscoding: &tests.MockTranscodingRepo{},
+		}
+		auth.Init(ds)
+		svc = NewDecider(ds)
+	})
+
+	Describe("MakeDecision", func() {
+		Context("Direct Play", func() {
+			It("allows direct play when profile matches", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 320, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, AudioCodecs: []string{"mp3"}, Protocols: []string{"http"}, MaxAudioChannels: 2},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+				Expect(decision.CanTranscode).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(BeEmpty())
+			})
+
+			It("rejects direct play when container doesn't match", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("container not supported"))
+			})
+
+			It("rejects direct play when codec doesn't match", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "ALAC", BitRate: 1000, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"m4a"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio codec not supported"))
+			})
+
+			It("rejects direct play when channels exceed limit", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 6}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}, MaxAudioChannels: 2},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio channels not supported"))
+			})
+
+			It("handles container aliases (aac -> m4a)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "AAC", BitRate: 256, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"aac"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("handles container aliases (mp4 -> m4a)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "AAC", BitRate: 256, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp4"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("handles codec aliases (adts -> aac)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "AAC", BitRate: 256, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"m4a"}, AudioCodecs: []string{"adts"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("allows when protocol list is empty (any protocol)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, AudioCodecs: []string{"flac"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("allows when both container and codec lists are empty (wildcard)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 128, Channels: 2}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{}, AudioCodecs: []string{}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+		})
+
+		Context("MaxAudioBitrate constraint", func() {
+			It("revokes direct play when bitrate exceeds maxAudioBitrate", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1500, Channels: 2}
+				ci := &ClientInfo{
+					MaxAudioBitrate: 500, // kbps
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio bitrate not supported"))
+			})
+		})
+
+		Context("Transcoding", func() {
+			It("selects transcoding when direct play isn't possible", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 44100, BitDepth: 16}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 256, // kbps
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, Protocols: []string{"http"}},
+					},
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http", MaxAudioChannels: 2},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetFormat).To(Equal("mp3"))
+				Expect(decision.TargetBitrate).To(Equal(256)) // kbps
+				Expect(decision.TranscodeReasons).To(ContainElement("container not supported"))
+			})
+
+			It("rejects lossy to lossless transcoding", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 320, Channels: 2}
+				ci := &ClientInfo{
+					TranscodingProfiles: []Profile{
+						{Container: "flac", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeFalse())
+			})
+
+			It("uses default bitrate when client doesn't specify", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, BitDepth: 16}
+				ci := &ClientInfo{
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetBitrate).To(Equal(defaultBitrate)) // 256 kbps
+			})
+
+			It("preserves lossy bitrate when under max", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "ogg", BitRate: 192, Channels: 2}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 256, // kbps
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetBitrate).To(Equal(192)) // source bitrate in kbps
+			})
+
+			It("rejects unsupported transcoding format", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2}
+				ci := &ClientInfo{
+					TranscodingProfiles: []Profile{
+						{Container: "aac", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeFalse())
+			})
+
+			It("applies maxAudioBitrate as final cap on transcoded stream", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 320, Channels: 2}
+				ci := &ClientInfo{
+					MaxAudioBitrate: 96, // kbps
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetBitrate).To(Equal(96)) // capped by maxAudioBitrate
+			})
+
+			It("selects first valid transcoding profile in order", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 48000, BitDepth: 16}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 320,
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, Protocols: []string{"http"}},
+					},
+					TranscodingProfiles: []Profile{
+						{Container: "opus", AudioCodec: "opus", Protocol: "http"},
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http", MaxAudioChannels: 2},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetFormat).To(Equal("opus"))
+			})
+		})
+
+		Context("Lossless to lossless transcoding", func() {
+			It("allows lossless to lossless when samplerate needs downsampling", func() {
+				// MockTranscodingRepo doesn't support "flac" format, so this would fail to find a config.
+				// This test documents the behavior: lossless→lossless requires server transcoding config.
+				mf := &model.MediaFile{ID: "1", Suffix: "dsf", Codec: "DSD", BitRate: 5644, Channels: 2, SampleRate: 176400, BitDepth: 1}
+				ci := &ClientInfo{
+					MaxAudioBitrate: 1000,
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TargetFormat).To(Equal("mp3"))
+			})
+
+			It("sets IsLossless=true on transcoded stream when target is lossless", func() {
+				// Simulate DSD→FLAC transcoding by using a mock that supports "flac"
+				mockTranscoding := &tests.MockTranscodingRepo{}
+				ds.MockedTranscoding = mockTranscoding
+				svc = NewDecider(ds)
+
+				// MockTranscodingRepo doesn't support flac, so this will skip lossless profile.
+				// Use mp3 which is supported as the fallback.
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 96000, BitDepth: 24}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 320,
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TranscodeStream.IsLossless).To(BeFalse()) // mp3 is lossy
+			})
+		})
+
+		Context("No compatible profile", func() {
+			It("returns error when nothing matches", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 6}
+				ci := &ClientInfo{}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.CanTranscode).To(BeFalse())
+				Expect(decision.ErrorReason).To(Equal("no compatible playback profile found"))
+			})
+		})
+
+		Context("Codec limitations on direct play", func() {
+			It("rejects direct play when codec limitation fails (required)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 512, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, AudioCodecs: []string{"mp3"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioBitrate, Comparison: ComparisonLessThanEqual, Values: []string{"320"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio bitrate not supported"))
+			})
+
+			It("allows direct play when optional limitation fails", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 512, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"mp3"}, AudioCodecs: []string{"mp3"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioBitrate, Comparison: ComparisonLessThanEqual, Values: []string{"320"}, Required: false},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("handles Equals comparison with multiple values", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "flac",
+							Limitations: []Limitation{
+								{Name: LimitationAudioChannels, Comparison: ComparisonEquals, Values: []string{"1", "2"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("rejects when Equals comparison doesn't match any value", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 6, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "flac",
+							Limitations: []Limitation{
+								{Name: LimitationAudioChannels, Comparison: ComparisonEquals, Values: []string{"1", "2"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+			})
+
+			It("rejects direct play when audioProfile limitation fails (required)", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "AAC", BitRate: 256, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"m4a"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "aac",
+							Limitations: []Limitation{
+								{Name: LimitationAudioProfile, Comparison: ComparisonEquals, Values: []string{"LC"}, Required: true},
+							},
+						},
+					},
+				}
+				// Source profile is empty (not yet populated from scanner), so Equals("LC") fails
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio profile not supported"))
+			})
+
+			It("allows direct play when audioProfile limitation is optional", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "m4a", Codec: "AAC", BitRate: 256, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"m4a"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "aac",
+							Limitations: []Limitation{
+								{Name: LimitationAudioProfile, Comparison: ComparisonEquals, Values: []string{"LC"}, Required: false},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeTrue())
+			})
+
+			It("rejects direct play due to samplerate limitation", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 96000, BitDepth: 24}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "flac",
+							Limitations: []Limitation{
+								{Name: LimitationAudioSamplerate, Comparison: ComparisonLessThanEqual, Values: []string{"48000"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(ContainElement("audio samplerate not supported"))
+			})
+		})
+
+		Context("Codec limitations on transcoded output", func() {
+			It("applies bitrate limitation to transcoded stream", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "mp3", Codec: "MP3", BitRate: 192, Channels: 2, SampleRate: 44100}
+				ci := &ClientInfo{
+					MaxAudioBitrate: 96, // force transcode
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioBitrate, Comparison: ComparisonLessThanEqual, Values: []string{"96"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TranscodeStream.Bitrate).To(Equal(96))
+			})
+
+			It("applies channel limitation to transcoded stream", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 6, SampleRate: 48000, BitDepth: 16}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 320,
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioChannels, Comparison: ComparisonLessThanEqual, Values: []string{"2"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TranscodeStream.Channels).To(Equal(2))
+			})
+
+			It("applies samplerate limitation to transcoded stream", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 96000, BitDepth: 24}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 320,
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioSamplerate, Comparison: ComparisonLessThanEqual, Values: []string{"48000"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeTrue())
+				Expect(decision.TranscodeStream.SampleRate).To(Equal(48000))
+			})
+
+			It("rejects transcoding profile when GreaterThanEqual cannot be satisfied", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 44100, BitDepth: 16}
+				ci := &ClientInfo{
+					MaxTranscodingAudioBitrate: 320,
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+					CodecProfiles: []CodecProfile{
+						{
+							Type: CodecProfileTypeAudio,
+							Name: "mp3",
+							Limitations: []Limitation{
+								{Name: LimitationAudioSamplerate, Comparison: ComparisonGreaterThanEqual, Values: []string{"96000"}, Required: true},
+							},
+						},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanTranscode).To(BeFalse())
+			})
+		})
+
+		Context("Typed transcode reasons from multiple profiles", func() {
+			It("collects reasons from each failed direct play profile", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "ogg", Codec: "Vorbis", BitRate: 128, Channels: 2, SampleRate: 48000}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+						{Containers: []string{"mp3"}, AudioCodecs: []string{"mp3"}, Protocols: []string{"http"}},
+						{Containers: []string{"m4a", "mp4"}, AudioCodecs: []string{"aac"}, Protocols: []string{"http"}},
+					},
+					TranscodingProfiles: []Profile{
+						{Container: "mp3", AudioCodec: "mp3", Protocol: "http"},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.CanDirectPlay).To(BeFalse())
+				Expect(decision.TranscodeReasons).To(HaveLen(3))
+				Expect(decision.TranscodeReasons[0]).To(Equal("container not supported"))
+				Expect(decision.TranscodeReasons[1]).To(Equal("container not supported"))
+				Expect(decision.TranscodeReasons[2]).To(Equal("container not supported"))
+			})
+		})
+
+		Context("Source stream details", func() {
+			It("populates source stream correctly with kbps bitrate", func() {
+				mf := &model.MediaFile{ID: "1", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 96000, BitDepth: 24, Duration: 300.5, Size: 50000000}
+				ci := &ClientInfo{
+					DirectPlayProfiles: []DirectPlayProfile{
+						{Containers: []string{"flac"}, Protocols: []string{"http"}},
+					},
+				}
+				decision, err := svc.MakeDecision(ctx, mf, ci)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(decision.SourceStream.Container).To(Equal("flac"))
+				Expect(decision.SourceStream.Codec).To(Equal("flac"))
+				Expect(decision.SourceStream.Bitrate).To(Equal(1000)) // kbps
+				Expect(decision.SourceStream.SampleRate).To(Equal(96000))
+				Expect(decision.SourceStream.BitDepth).To(Equal(24))
+				Expect(decision.SourceStream.Channels).To(Equal(2))
+			})
+		})
+	})
+
+	Describe("Token round-trip", func() {
+		It("creates and parses a direct play token", func() {
+			decision := &Decision{
+				MediaID:       "media-123",
+				CanDirectPlay: true,
+			}
+			token, err := svc.CreateTranscodeParams(decision)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(token).ToNot(BeEmpty())
+
+			params, err := svc.ParseTranscodeParams(token)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(params.MediaID).To(Equal("media-123"))
+			Expect(params.DirectPlay).To(BeTrue())
+			Expect(params.TargetFormat).To(BeEmpty())
+		})
+
+		It("creates and parses a transcode token with kbps bitrate", func() {
+			decision := &Decision{
+				MediaID:        "media-456",
+				CanDirectPlay:  false,
+				CanTranscode:   true,
+				TargetFormat:   "mp3",
+				TargetBitrate:  256, // kbps
+				TargetChannels: 2,
+			}
+			token, err := svc.CreateTranscodeParams(decision)
+			Expect(err).ToNot(HaveOccurred())
+
+			params, err := svc.ParseTranscodeParams(token)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(params.MediaID).To(Equal("media-456"))
+			Expect(params.DirectPlay).To(BeFalse())
+			Expect(params.TargetFormat).To(Equal("mp3"))
+			Expect(params.TargetBitrate).To(Equal(256)) // kbps
+			Expect(params.TargetChannels).To(Equal(2))
+		})
+
+		It("rejects an invalid token", func() {
+			_, err := svc.ParseTranscodeParams("invalid-token")
+			Expect(err).To(HaveOccurred())
+		})
+	})
+})

core/wire_providers.go

@@ -8,6 +8,7 @@ import (
 	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/core/playback"
 	"github.com/navidrome/navidrome/core/scrobbler"
+	"github.com/navidrome/navidrome/core/transcode"
 )
 
 var Set = wire.NewSet(
@@ -20,6 +21,7 @@ var Set = wire.NewSet(
 	NewLibrary,
 	NewUser,
 	NewMaintenance,
+	transcode.NewDecider,
 	agents.GetAgents,
 	external.NewProvider,
 	wire.Bind(new(external.Agents), new(*agents.Agents)),

db/migrations/20260205120000_add_codec_to_media_file.sql

@@ -0,0 +1,11 @@
+-- +goose Up
+-- +goose StatementBegin
+ALTER TABLE media_file ADD COLUMN codec VARCHAR(255) DEFAULT '' NOT NULL;
+CREATE INDEX IF NOT EXISTS media_file_codec ON media_file(codec);
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+DROP INDEX IF EXISTS media_file_codec;
+ALTER TABLE media_file DROP COLUMN codec;
+-- +goose StatementEnd

go.mod

@@ -7,7 +7,7 @@ replace (
 	github.com/dhowden/tag v0.0.0-20240417053706-3d75831295e8 => github.com/deluan/tag v0.0.0-20241002021117-dfe5e6ea396d
 
 	// Fork to implement raw tags support
-	go.senan.xyz/taglib => github.com/deluan/go-taglib v0.0.0-20260119020817-8753c7531798
+	go.senan.xyz/taglib => github.com/deluan/go-taglib v0.0.0-20260205042457-5d80806aee57
 )
 
 require (

go.sum

@@ -36,8 +36,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.0 h1:NMZiJj8QnKe1LgsbDayM4UoHwbvwDRwnI3hwNaAHRnc=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.4.0/go.mod h1:ZXNYxsqcloTdSy/rNShjYzMhyjf0LaoftYK0p+A3h40=
-github.com/deluan/go-taglib v0.0.0-20260119020817-8753c7531798 h1:q4fvcIK/LxElpyQILCejG6WPYjVb2F/4P93+k017ANk=
-github.com/deluan/go-taglib v0.0.0-20260119020817-8753c7531798/go.mod h1:sKDN0U4qXDlq6LFK+aOAkDH4Me5nDV1V/A4B+B69xBA=
+github.com/deluan/go-taglib v0.0.0-20260205042457-5d80806aee57 h1:SXIwfjzTv0UzoUWpFREl8p3AxXVLmbcto1/ISih11a0=
+github.com/deluan/go-taglib v0.0.0-20260205042457-5d80806aee57/go.mod h1:sKDN0U4qXDlq6LFK+aOAkDH4Me5nDV1V/A4B+B69xBA=
 github.com/deluan/rest v0.0.0-20211102003136-6260bc399cbf h1:tb246l2Zmpt/GpF9EcHCKTtwzrd0HGfEmoODFA/qnk4=
 github.com/deluan/rest v0.0.0-20211102003136-6260bc399cbf/go.mod h1:tSgDythFsl0QgS/PFWfIZqcJKnkADWneY80jaVRlqK8=
 github.com/deluan/sanitize v0.0.0-20241120162836-fdfd8fdfaa55 h1:wSCnggTs2f2ji6nFwQmfwgINcmSMj0xF0oHnoyRSPe4=

model/mediafile.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/gohugoio/hashstructure"
 	"github.com/navidrome/navidrome/conf"
+	confmime "github.com/navidrome/navidrome/conf/mime"
 	"github.com/navidrome/navidrome/consts"
 	"github.com/navidrome/navidrome/utils"
 	"github.com/navidrome/navidrome/utils/slice"
@@ -56,6 +57,7 @@ type MediaFile struct {
 	SampleRate           int      `structs:"sample_rate" json:"sampleRate"`
 	BitDepth             int      `structs:"bit_depth" json:"bitDepth"`
 	Channels             int      `structs:"channels" json:"channels"`
+	Codec                string   `structs:"codec" json:"codec"`
 	Genre                string   `structs:"genre" json:"genre"`
 	Genres               Genres   `structs:"-" json:"genres,omitempty"`
 	SortTitle            string   `structs:"sort_title" json:"sortTitle,omitempty"`
@@ -161,6 +163,79 @@ func (mf MediaFile) AbsolutePath() string {
 	return filepath.Join(mf.LibraryPath, mf.Path)
 }
 
+// AudioCodec returns the audio codec for this file.
+// Uses the stored Codec field if available, otherwise infers from Suffix and audio properties.
+func (mf MediaFile) AudioCodec() string {
+	// If we have a stored codec from scanning, normalize and return it
+	if mf.Codec != "" {
+		return strings.ToLower(mf.Codec)
+	}
+	// Fallback: infer from Suffix + BitDepth
+	return mf.inferCodecFromSuffix()
+}
+
+// inferCodecFromSuffix infers the codec from the file extension when Codec field is empty.
+func (mf MediaFile) inferCodecFromSuffix() string {
+	switch strings.ToLower(mf.Suffix) {
+	case "mp3", "mpga":
+		return "mp3"
+	case "mp2":
+		return "mp2"
+	case "ogg", "oga":
+		return "vorbis"
+	case "opus":
+		return "opus"
+	case "mpc":
+		return "mpc"
+	case "wma":
+		return "wma"
+	case "flac":
+		return "flac"
+	case "wav":
+		return "pcm"
+	case "aif", "aiff", "aifc":
+		return "pcm"
+	case "ape":
+		return "ape"
+	case "wv", "wvp":
+		return "wv"
+	case "tta":
+		return "tta"
+	case "tak":
+		return "tak"
+	case "shn":
+		return "shn"
+	case "dsf", "dff":
+		return "dsd"
+	case "m4a":
+		// AAC if BitDepth==0, ALAC if BitDepth>0
+		if mf.BitDepth > 0 {
+			return "alac"
+		}
+		return "aac"
+	case "m4b", "m4p", "m4r":
+		return "aac"
+	default:
+		return ""
+	}
+}
+
+// IsLossless returns true if this file uses a lossless codec.
+func (mf MediaFile) IsLossless() bool {
+	codec := mf.AudioCodec()
+	// Primary: codec-based check (most accurate for containers like M4A)
+	switch codec {
+	case "flac", "alac", "pcm", "ape", "wv", "tta", "tak", "shn", "dsd":
+		return true
+	}
+	// Secondary: suffix-based check using configurable list from YAML
+	if slices.Contains(confmime.LosslessFormats, mf.Suffix) {
+		return true
+	}
+	// Fallback heuristic: if BitDepth is set, it's likely lossless
+	return mf.BitDepth > 0
+}
+
 type MediaFiles []MediaFile
 
 // ToAlbum creates an Album object based on the attributes of this MediaFiles collection.
@@ -354,7 +429,7 @@ type MediaFileCursor iter.Seq2[MediaFile, error]
 type MediaFileRepository interface {
 	CountAll(options ...QueryOptions) (int64, error)
 	CountBySuffix(options ...QueryOptions) (map[string]int64, error)
-	Exists(ids ...string) (bool, error)
+	Exists(id string) (bool, error)
 	Put(m *MediaFile) error
 	Get(id string) (*MediaFile, error)
 	GetWithParticipants(id string) (*MediaFile, error)

model/mediafile_test.go

@@ -475,7 +475,7 @@ var _ = Describe("MediaFile", func() {
 		DeferCleanup(configtest.SetupConfig())
 		conf.Server.EnableMediaFileCoverArt = true
 	})
-	Describe(".CoverArtId()", func() {
+	Describe("CoverArtId", func() {
 		It("returns its own id if it HasCoverArt", func() {
 			mf := MediaFile{ID: "111", AlbumID: "1", HasCoverArt: true}
 			id := mf.CoverArtID()
@@ -496,6 +496,94 @@ var _ = Describe("MediaFile", func() {
 			Expect(id.ID).To(Equal(mf.AlbumID))
 		})
 	})
+
+	Describe("AudioCodec", func() {
+		It("returns normalized stored codec when available", func() {
+			mf := MediaFile{Codec: "AAC", Suffix: "m4a"}
+			Expect(mf.AudioCodec()).To(Equal("aac"))
+		})
+
+		It("returns stored codec lowercased", func() {
+			mf := MediaFile{Codec: "ALAC", Suffix: "m4a"}
+			Expect(mf.AudioCodec()).To(Equal("alac"))
+		})
+
+		DescribeTable("infers codec from suffix when Codec field is empty",
+			func(suffix string, bitDepth int, expected string) {
+				mf := MediaFile{Suffix: suffix, BitDepth: bitDepth}
+				Expect(mf.AudioCodec()).To(Equal(expected))
+			},
+			Entry("mp3", "mp3", 0, "mp3"),
+			Entry("mpga", "mpga", 0, "mp3"),
+			Entry("mp2", "mp2", 0, "mp2"),
+			Entry("ogg", "ogg", 0, "vorbis"),
+			Entry("oga", "oga", 0, "vorbis"),
+			Entry("opus", "opus", 0, "opus"),
+			Entry("mpc", "mpc", 0, "mpc"),
+			Entry("wma", "wma", 0, "wma"),
+			Entry("flac", "flac", 0, "flac"),
+			Entry("wav", "wav", 0, "pcm"),
+			Entry("aif", "aif", 0, "pcm"),
+			Entry("aiff", "aiff", 0, "pcm"),
+			Entry("aifc", "aifc", 0, "pcm"),
+			Entry("ape", "ape", 0, "ape"),
+			Entry("wv", "wv", 0, "wv"),
+			Entry("wvp", "wvp", 0, "wv"),
+			Entry("tta", "tta", 0, "tta"),
+			Entry("tak", "tak", 0, "tak"),
+			Entry("shn", "shn", 0, "shn"),
+			Entry("dsf", "dsf", 0, "dsd"),
+			Entry("dff", "dff", 0, "dsd"),
+			Entry("m4a with BitDepth=0 (AAC)", "m4a", 0, "aac"),
+			Entry("m4a with BitDepth>0 (ALAC)", "m4a", 16, "alac"),
+			Entry("m4b", "m4b", 0, "aac"),
+			Entry("m4p", "m4p", 0, "aac"),
+			Entry("m4r", "m4r", 0, "aac"),
+			Entry("unknown suffix", "xyz", 0, ""),
+		)
+
+		It("prefers stored codec over suffix inference", func() {
+			mf := MediaFile{Codec: "ALAC", Suffix: "m4a", BitDepth: 0}
+			Expect(mf.AudioCodec()).To(Equal("alac"))
+		})
+	})
+
+	Describe("IsLossless", func() {
+		BeforeEach(func() {
+			DeferCleanup(configtest.SetupConfig())
+		})
+
+		DescribeTable("detects lossless codecs",
+			func(codec string, suffix string, bitDepth int, expected bool) {
+				mf := MediaFile{Codec: codec, Suffix: suffix, BitDepth: bitDepth}
+				Expect(mf.IsLossless()).To(Equal(expected))
+			},
+			Entry("flac", "FLAC", "flac", 16, true),
+			Entry("alac", "ALAC", "m4a", 24, true),
+			Entry("pcm via wav", "", "wav", 16, true),
+			Entry("pcm via aiff", "", "aiff", 24, true),
+			Entry("ape", "", "ape", 16, true),
+			Entry("wv", "", "wv", 0, true),
+			Entry("tta", "", "tta", 0, true),
+			Entry("tak", "", "tak", 0, true),
+			Entry("shn", "", "shn", 0, true),
+			Entry("dsd", "", "dsf", 0, true),
+			Entry("mp3 is lossy", "MP3", "mp3", 0, false),
+			Entry("aac is lossy", "AAC", "m4a", 0, false),
+			Entry("vorbis is lossy", "", "ogg", 0, false),
+			Entry("opus is lossy", "", "opus", 0, false),
+		)
+
+		It("detects lossless via BitDepth fallback when codec is unknown", func() {
+			mf := MediaFile{Suffix: "xyz", BitDepth: 24}
+			Expect(mf.IsLossless()).To(BeTrue())
+		})
+
+		It("returns false for unknown with no BitDepth", func() {
+			mf := MediaFile{Suffix: "xyz", BitDepth: 0}
+			Expect(mf.IsLossless()).To(BeFalse())
+		})
+	})
 })
 
 func t(v string) time.Time {

model/metadata/map_mediafile.go

@@ -65,6 +65,7 @@ func (md Metadata) ToMediaFile(libID int, folderID string) model.MediaFile {
 	mf.SampleRate = md.AudioProperties().SampleRate
 	mf.BitDepth = md.AudioProperties().BitDepth
 	mf.Channels = md.AudioProperties().Channels
+	mf.Codec = md.AudioProperties().Codec
 	mf.Path = md.FilePath()
 	mf.Suffix = md.Suffix()
 	mf.Size = md.Size()

model/metadata/metadata.go

@@ -35,6 +35,7 @@ type AudioProperties struct {
 	BitDepth   int
 	SampleRate int
 	Channels   int
+	Codec      string
 }
 
 type Date string
@@ -250,7 +251,15 @@ func processPairMapping(name model.TagName, mapping model.TagConf, lowered model
 	id3Base := parseID3Pairs(name, lowered)
 
 	if len(aliasValues) > 0 {
-		id3Base = append(id3Base, parseVorbisPairs(aliasValues)...)
+		// For lyrics, don't use parseVorbisPairs as parentheses in lyrics content
+		// should not be interpreted as language keys (e.g. "(intro)" is not a language)
+		if name == model.TagLyrics {
+			for _, v := range aliasValues {
+				id3Base = append(id3Base, NewPair("xxx", v))
+			}
+		} else {
+			id3Base = append(id3Base, parseVorbisPairs(aliasValues)...)
+		}
 	}
 	return id3Base
 }

model/metadata/metadata_test.go

@@ -246,6 +246,18 @@ var _ = Describe("Metadata", func() {
 					metadata.NewPair("eng", "Lyrics"),
 				))
 			})
+
+			It("should preserve lyrics starting with parentheses from alias tags", func() {
+				props.Tags = model.RawTags{
+					"LYRICS": {"(line one)\nline two\nline three"},
+				}
+				md = metadata.New(filePath, props)
+
+				Expect(md.All()).To(HaveKey(model.TagLyrics))
+				Expect(md.Strings(model.TagLyrics)).To(ContainElements(
+					metadata.NewPair("xxx", "(line one)\nline two\nline three"),
+				))
+			})
 		})
 
 		Describe("ReplayGain", func() {

persistence/mediafile_repository.go

@@ -143,29 +143,8 @@ func (r *mediaFileRepository) CountBySuffix(options ...model.QueryOptions) (map[
 	return counts, nil
 }
 
-// Exists checks if all given media file IDs exist in the database and are accessible to the current user.
-// If no IDs are provided, it returns true. Duplicate IDs are handled correctly.
-// If any of the IDs do not exist or are not accessible, it returns false.
-func (r *mediaFileRepository) Exists(ids ...string) (bool, error) {
-	if len(ids) == 0 {
-		return true, nil
-	}
-	uniqueIds := slice.Unique(ids)
-
-	// Process in batches to avoid hitting SQLITE_MAX_VARIABLE_NUMBER limit (default 999)
-	const batchSize = 300
-	var totalCount int64
-	for batch := range slices.Chunk(uniqueIds, batchSize) {
-		existsQuery := Select("count(*) as exist").From("media_file").Where(Eq{"media_file.id": batch})
-		existsQuery = r.applyLibraryFilter(existsQuery)
-		var res struct{ Exist int64 }
-		err := r.queryOne(existsQuery, &res)
-		if err != nil {
-			return false, err
-		}
-		totalCount += res.Exist
-	}
-	return totalCount == int64(len(uniqueIds)), nil
+func (r *mediaFileRepository) Exists(id string) (bool, error) {
+	return r.exists(Eq{"media_file.id": id})
 }
 
 func (r *mediaFileRepository) Put(m *model.MediaFile) error {

persistence/playlist_repository.go

@@ -285,13 +285,16 @@ func (r *playlistRepository) refreshSmartPlaylist(pls *model.Playlist) bool {
 	}
 
 	// Update when the playlist was last refreshed (for cache purposes)
-	updSql := Update(r.tableName).Set("evaluated_at", time.Now()).Where(Eq{"id": pls.ID})
+	now := time.Now()
+	updSql := Update(r.tableName).Set("evaluated_at", now).Where(Eq{"id": pls.ID})
 	_, err = r.executeSQL(updSql)
 	if err != nil {
 		log.Error(r.ctx, "Error updating smart playlist", "playlist", pls.Name, "id", pls.ID, err)
 		return false
 	}
 
+	pls.EvaluatedAt = &now
+
 	log.Debug(r.ctx, "Refreshed playlist", "playlist", pls.Name, "id", pls.ID, "numTracks", pls.SongCount, "elapsed", time.Since(start))
 
 	return true

persistence/playlist_repository_test.go

@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"github.com/navidrome/navidrome/conf"
+	"github.com/navidrome/navidrome/conf/configtest"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/criteria"
@@ -160,14 +161,23 @@ var _ = Describe("PlaylistRepository", func() {
 			})
 		})
 
-		// TODO Validate these tests
-		XContext("child smart playlists", func() {
-			When("refresh day has expired", func() {
+		Context("child smart playlists", func() {
+			BeforeEach(func() {
+				DeferCleanup(configtest.SetupConfig())
+			})
+
+			When("refresh delay has expired", func() {
 				It("should refresh tracks for smart playlist referenced in parent smart playlist criteria", func() {
 					conf.Server.SmartPlaylistRefreshDelay = -1 * time.Second
 
-					nestedPls := model.Playlist{Name: "Nested", OwnerID: "userid", Rules: rules}
+					childRules := &criteria.Criteria{
+						Expression: criteria.All{
+							criteria.Contains{"title": "Day"},
+						},
+					}
+					nestedPls := model.Playlist{Name: "Nested", OwnerID: "userid", Public: true, Rules: childRules}
 					Expect(repo.Put(&nestedPls)).To(Succeed())
+					DeferCleanup(func() { _ = repo.Delete(nestedPls.ID) })
 
 					parentPls := model.Playlist{Name: "Parent", OwnerID: "userid", Rules: &criteria.Criteria{
 						Expression: criteria.All{
@@ -175,45 +185,69 @@ var _ = Describe("PlaylistRepository", func() {
 						},
 					}}
 					Expect(repo.Put(&parentPls)).To(Succeed())
+					DeferCleanup(func() { _ = repo.Delete(parentPls.ID) })
 
+					// Nested playlist has not been evaluated yet
 					nestedPlsRead, err := repo.Get(nestedPls.ID)
 					Expect(err).ToNot(HaveOccurred())
+					Expect(nestedPlsRead.EvaluatedAt).To(BeNil())
 
-					_, err = repo.GetWithTracks(parentPls.ID, true, false)
+					// Getting parent with refresh should recursively refresh the nested playlist
+					pls, err := repo.GetWithTracks(parentPls.ID, true, false)
 					Expect(err).ToNot(HaveOccurred())
+					Expect(pls.EvaluatedAt).ToNot(BeNil())
+					Expect(*pls.EvaluatedAt).To(BeTemporally("~", time.Now(), 2*time.Second))
 
-					// Check that the nested playlist was refreshed by parent get by verifying evaluatedAt is updated since first nestedPls get
+					// Parent should have tracks from the nested playlist
+					Expect(pls.Tracks).To(HaveLen(1))
+					Expect(pls.Tracks[0].MediaFileID).To(Equal(songDayInALife.ID))
+
+					// Nested playlist should now have been refreshed (EvaluatedAt set)
 					nestedPlsAfterParentGet, err := repo.Get(nestedPls.ID)
 					Expect(err).ToNot(HaveOccurred())
-
-					Expect(*nestedPlsAfterParentGet.EvaluatedAt).To(BeTemporally(">", *nestedPlsRead.EvaluatedAt))
+					Expect(nestedPlsAfterParentGet.EvaluatedAt).ToNot(BeNil())
+					Expect(*nestedPlsAfterParentGet.EvaluatedAt).To(BeTemporally("~", time.Now(), 2*time.Second))
 				})
 			})
 
-			When("refresh day has not expired", func() {
+			When("refresh delay has not expired", func() {
 				It("should NOT refresh tracks for smart playlist referenced in parent smart playlist criteria", func() {
 					conf.Server.SmartPlaylistRefreshDelay = 1 * time.Hour
+					childEvaluatedAt := time.Now().Add(-30 * time.Minute)
 
-					nestedPls := model.Playlist{Name: "Nested", OwnerID: "userid", Rules: rules}
+					childRules := &criteria.Criteria{
+						Expression: criteria.All{
+							criteria.Contains{"title": "Day"},
+						},
+					}
+					nestedPls := model.Playlist{Name: "Nested", OwnerID: "userid", Public: true, Rules: childRules, EvaluatedAt: &childEvaluatedAt}
 					Expect(repo.Put(&nestedPls)).To(Succeed())
+					DeferCleanup(func() { _ = repo.Delete(nestedPls.ID) })
 
+					// Parent has no EvaluatedAt, so it WILL refresh, but the child should not
 					parentPls := model.Playlist{Name: "Parent", OwnerID: "userid", Rules: &criteria.Criteria{
 						Expression: criteria.All{
 							criteria.InPlaylist{"id": nestedPls.ID},
 						},
 					}}
 					Expect(repo.Put(&parentPls)).To(Succeed())
+					DeferCleanup(func() { _ = repo.Delete(parentPls.ID) })
 
 					nestedPlsRead, err := repo.Get(nestedPls.ID)
 					Expect(err).ToNot(HaveOccurred())
 
-					_, err = repo.GetWithTracks(parentPls.ID, true, false)
+					// Getting parent with refresh should NOT recursively refresh the nested playlist
+					parent, err := repo.GetWithTracks(parentPls.ID, true, false)
 					Expect(err).ToNot(HaveOccurred())
 
-					// Check that the nested playlist was not refreshed by parent get by verifying evaluatedAt is not updated since first nestedPls get
+					// Parent should have been refreshed (its EvaluatedAt was nil)
+					Expect(parent.EvaluatedAt).ToNot(BeNil())
+					Expect(*parent.EvaluatedAt).To(BeTemporally("~", time.Now(), 2*time.Second))
+
+					// Nested playlist should NOT have been refreshed (still within delay window)
 					nestedPlsAfterParentGet, err := repo.Get(nestedPls.ID)
 					Expect(err).ToNot(HaveOccurred())
-
+					Expect(*nestedPlsAfterParentGet.EvaluatedAt).To(BeTemporally("~", childEvaluatedAt, time.Second))
 					Expect(*nestedPlsAfterParentGet.EvaluatedAt).To(Equal(*nestedPlsRead.EvaluatedAt))
 				})
 			})

server/subsonic/album_lists_test.go

@@ -27,7 +27,7 @@ var _ = Describe("Album Lists", func() {
 		ds = &tests.MockDataStore{}
 		auth.Init(ds)
 		mockRepo = ds.Album(ctx).(*tests.MockAlbumRepo)
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 	})
 

server/subsonic/api.go

@@ -16,6 +16,7 @@ import (
 	"github.com/navidrome/navidrome/core/metrics"
 	"github.com/navidrome/navidrome/core/playback"
 	"github.com/navidrome/navidrome/core/scrobbler"
+	"github.com/navidrome/navidrome/core/transcode"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/server"
@@ -31,40 +32,42 @@ type handlerRaw = func(http.ResponseWriter, *http.Request) (*responses.Subsonic,
 
 type Router struct {
 	http.Handler
-	ds        model.DataStore
-	artwork   artwork.Artwork
-	streamer  core.MediaStreamer
-	archiver  core.Archiver
-	players   core.Players
-	provider  external.Provider
-	playlists core.Playlists
-	scanner   model.Scanner
-	broker    events.Broker
-	scrobbler scrobbler.PlayTracker
-	share     core.Share
-	playback  playback.PlaybackServer
-	metrics   metrics.Metrics
+	ds                model.DataStore
+	artwork           artwork.Artwork
+	streamer          core.MediaStreamer
+	archiver          core.Archiver
+	players           core.Players
+	provider          external.Provider
+	playlists         core.Playlists
+	scanner           model.Scanner
+	broker            events.Broker
+	scrobbler         scrobbler.PlayTracker
+	share             core.Share
+	playback          playback.PlaybackServer
+	metrics           metrics.Metrics
+	transcodeDecision transcode.Decider
 }
 
 func New(ds model.DataStore, artwork artwork.Artwork, streamer core.MediaStreamer, archiver core.Archiver,
 	players core.Players, provider external.Provider, scanner model.Scanner, broker events.Broker,
 	playlists core.Playlists, scrobbler scrobbler.PlayTracker, share core.Share, playback playback.PlaybackServer,
-	metrics metrics.Metrics,
+	metrics metrics.Metrics, transcodeDecision transcode.Decider,
 ) *Router {
 	r := &Router{
-		ds:        ds,
-		artwork:   artwork,
-		streamer:  streamer,
-		archiver:  archiver,
-		players:   players,
-		provider:  provider,
-		playlists: playlists,
-		scanner:   scanner,
-		broker:    broker,
-		scrobbler: scrobbler,
-		share:     share,
-		playback:  playback,
-		metrics:   metrics,
+		ds:                ds,
+		artwork:           artwork,
+		streamer:          streamer,
+		archiver:          archiver,
+		players:           players,
+		provider:          provider,
+		playlists:         playlists,
+		scanner:           scanner,
+		broker:            broker,
+		scrobbler:         scrobbler,
+		share:             share,
+		playback:          playback,
+		metrics:           metrics,
+		transcodeDecision: transcodeDecision,
 	}
 	r.Handler = r.routes()
 	return r
@@ -169,6 +172,8 @@ func (api *Router) routes() http.Handler {
 			h(r, "getLyricsBySongId", api.GetLyricsBySongId)
 			hr(r, "stream", api.Stream)
 			hr(r, "download", api.Download)
+			hr(r, "getTranscodeDecision", api.GetTranscodeDecision)
+			hr(r, "getTranscodeStream", api.GetTranscodeStream)
 		})
 		r.Group(func(r chi.Router) {
 			// configure request throttling

server/subsonic/media_annotation.go

@@ -168,26 +168,15 @@ func (api *Router) Scrobble(r *http.Request) (*responses.Subsonic, error) {
 	position := p.IntOr("position", 0)
 	ctx := r.Context()
 
-	// Validate all IDs exist before processing (OpenSubsonic compliance)
-	exists, err := api.ds.MediaFile(ctx).Exists(ids...)
-	if err != nil {
-		return nil, err
-	}
-	if !exists {
-		return nil, newError(responses.ErrorDataNotFound, "Media file not found")
-	}
-
 	if submission {
 		err := api.scrobblerSubmit(ctx, ids, times)
 		if err != nil {
 			log.Error(ctx, "Error registering scrobbles", "ids", ids, "times", times, err)
-			return nil, err
 		}
 	} else {
 		err := api.scrobblerNowPlaying(ctx, ids[0], position)
 		if err != nil {
 			log.Error(ctx, "Error setting NowPlaying", "id", ids[0], err)
-			return nil, err
 		}
 	}
 

server/subsonic/media_annotation_test.go

@@ -27,16 +27,10 @@ var _ = Describe("MediaAnnotationController", func() {
 		ds = &tests.MockDataStore{}
 		playTracker = &fakePlayTracker{}
 		eventBroker = &fakeEventBroker{}
-		router = New(ds, nil, nil, nil, nil, nil, nil, eventBroker, nil, playTracker, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, eventBroker, nil, playTracker, nil, nil, nil, nil)
 	})
 
 	Describe("Scrobble", func() {
-		BeforeEach(func() {
-			// Populate mock with valid media files
-			_ = ds.MediaFile(ctx).Put(&model.MediaFile{ID: "12"})
-			_ = ds.MediaFile(ctx).Put(&model.MediaFile{ID: "34"})
-		})
-
 		It("submit all scrobbles with only the id", func() {
 			submissionTime := time.Now()
 			r := newGetRequest("id=12", "id=34")
@@ -77,27 +71,10 @@ var _ = Describe("MediaAnnotationController", func() {
 			Expect(playTracker.Submissions).To(BeEmpty())
 		})
 
-		It("returns error when any id is invalid", func() {
-			r := newGetRequest("id=invalid")
-
-			_, err := router.Scrobble(r)
-
-			Expect(err).To(MatchError(ContainSubstring("not found")))
-			Expect(playTracker.Submissions).To(BeEmpty())
-		})
-
-		It("returns error and does not scrobble when mix of valid and invalid ids", func() {
-			r := newGetRequest("id=12", "id=invalid")
-
-			_, err := router.Scrobble(r)
-
-			Expect(err).To(MatchError(ContainSubstring("not found")))
-			Expect(playTracker.Submissions).To(BeEmpty())
-		})
-
 		Context("submission=false", func() {
 			var req *http.Request
 			BeforeEach(func() {
+				_ = ds.MediaFile(ctx).Put(&model.MediaFile{ID: "12"})
 				ctx = request.WithPlayer(ctx, model.Player{ID: "player-1"})
 				req = newGetRequest("id=12", "submission=false")
 				req = req.WithContext(ctx)
@@ -117,16 +94,6 @@ var _ = Describe("MediaAnnotationController", func() {
 				Expect(playTracker.Playing).To(HaveLen(1))
 				Expect(playTracker.Playing).To(HaveKey("player-1"))
 			})
-
-			It("returns error when id is invalid", func() {
-				req = newGetRequest("id=invalid", "submission=false")
-				req = req.WithContext(ctx)
-
-				_, err := router.Scrobble(req)
-
-				Expect(err).To(MatchError(ContainSubstring("not found")))
-				Expect(playTracker.Playing).To(BeEmpty())
-			})
 		})
 	})
 })

server/subsonic/media_retrieval_test.go

@@ -33,7 +33,7 @@ var _ = Describe("MediaRetrievalController", func() {
 			MockedMediaFile: mockRepo,
 		}
 		artwork = &fakeArtwork{data: "image data"}
-		router = New(ds, artwork, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, artwork, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 		DeferCleanup(configtest.SetupConfig())
 		conf.Server.LyricsPriority = "embedded,.lrc"

server/subsonic/opensubsonic.go

@@ -13,6 +13,7 @@ func (api *Router) GetOpenSubsonicExtensions(_ *http.Request) (*responses.Subson
 		{Name: "formPost", Versions: []int32{1}},
 		{Name: "songLyrics", Versions: []int32{1}},
 		{Name: "indexBasedQueue", Versions: []int32{1}},
+		{Name: "transcoding", Versions: []int32{1}},
 	}
 	return response, nil
 }

server/subsonic/opensubsonic_test.go

@@ -19,7 +19,7 @@ var _ = Describe("GetOpenSubsonicExtensions", func() {
 	)
 
 	BeforeEach(func() {
-		router = subsonic.New(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = subsonic.New(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		w = httptest.NewRecorder()
 		r = httptest.NewRequest("GET", "/getOpenSubsonicExtensions?f=json", nil)
 	})
@@ -35,11 +35,12 @@ var _ = Describe("GetOpenSubsonicExtensions", func() {
 		err := json.Unmarshal(w.Body.Bytes(), &response)
 		Expect(err).NotTo(HaveOccurred())
 		Expect(*response.Subsonic.OpenSubsonicExtensions).To(SatisfyAll(
-			HaveLen(4),
+			HaveLen(5),
 			ContainElement(responses.OpenSubsonicExtension{Name: "transcodeOffset", Versions: []int32{1}}),
 			ContainElement(responses.OpenSubsonicExtension{Name: "formPost", Versions: []int32{1}}),
 			ContainElement(responses.OpenSubsonicExtension{Name: "songLyrics", Versions: []int32{1}}),
 			ContainElement(responses.OpenSubsonicExtension{Name: "indexBasedQueue", Versions: []int32{1}}),
+			ContainElement(responses.OpenSubsonicExtension{Name: "transcoding", Versions: []int32{1}}),
 		))
 	})
 })

server/subsonic/playlists.go

@@ -12,6 +12,7 @@ import (
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/request"
 	"github.com/navidrome/navidrome/server/subsonic/responses"
+	. "github.com/navidrome/navidrome/utils/gg"
 	"github.com/navidrome/navidrome/utils/req"
 	"github.com/navidrome/navidrome/utils/slice"
 )
@@ -162,7 +163,11 @@ func (api *Router) buildPlaylist(ctx context.Context, p model.Playlist) response
 	pls.Duration = int32(p.Duration)
 	pls.Created = p.CreatedAt
 	if p.IsSmartPlaylist() {
-		pls.Changed = time.Now()
+		if p.EvaluatedAt != nil {
+			pls.Changed = *p.EvaluatedAt
+		} else {
+			pls.Changed = time.Now()
+		}
 	} else {
 		pls.Changed = p.UpdatedAt
 	}
@@ -176,6 +181,24 @@ func (api *Router) buildPlaylist(ctx context.Context, p model.Playlist) response
 	pls.Owner = p.OwnerName
 	pls.Public = p.Public
 	pls.CoverArt = p.CoverArtID().String()
+	pls.OpenSubsonicPlaylist = buildOSPlaylist(ctx, p)
 
 	return pls
 }
+
+func buildOSPlaylist(ctx context.Context, p model.Playlist) *responses.OpenSubsonicPlaylist {
+	pls := responses.OpenSubsonicPlaylist{}
+
+	if p.IsSmartPlaylist() {
+		pls.Readonly = true
+
+		if p.EvaluatedAt != nil {
+			pls.ValidUntil = P(p.EvaluatedAt.Add(conf.Server.SmartPlaylistRefreshDelay))
+		}
+	} else {
+		user, ok := request.UserFrom(ctx)
+		pls.Readonly = !ok || p.OwnerID != user.ID
+	}
+
+	return &pls
+}

server/subsonic/playlists_test.go

@@ -7,6 +7,7 @@ import (
 	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/model/criteria"
 	"github.com/navidrome/navidrome/model/request"
 	"github.com/navidrome/navidrome/tests"
 	. "github.com/onsi/ginkgo/v2"
@@ -23,98 +24,196 @@ var _ = Describe("buildPlaylist", func() {
 
 	BeforeEach(func() {
 		ds = &tests.MockDataStore{}
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 		ctx = context.Background()
-
-		createdAt := time.Date(2023, 1, 15, 10, 30, 0, 0, time.UTC)
-		updatedAt := time.Date(2023, 2, 20, 14, 45, 0, 0, time.UTC)
-
-		playlist = model.Playlist{
-			ID:        "pls-1",
-			Name:      "My Playlist",
-			Comment:   "Test comment",
-			OwnerName: "admin",
-			Public:    true,
-			SongCount: 10,
-			Duration:  600,
-			CreatedAt: createdAt,
-			UpdatedAt: updatedAt,
-		}
 	})
 
-	Context("with minimal client", func() {
+	Describe("normal playlist", func() {
 		BeforeEach(func() {
-			conf.Server.Subsonic.MinimalClients = "minimal-client"
-			player := model.Player{Client: "minimal-client"}
-			ctx = request.WithPlayer(ctx, player)
+			createdAt := time.Date(2023, 1, 15, 10, 30, 0, 0, time.UTC)
+			updatedAt := time.Date(2023, 2, 20, 14, 45, 0, 0, time.UTC)
+
+			playlist = model.Playlist{
+				ID:        "pls-1",
+				Name:      "My Playlist",
+				Comment:   "Test comment",
+				OwnerName: "admin",
+				OwnerID:   "1234",
+				Public:    true,
+				SongCount: 10,
+				Duration:  600,
+				CreatedAt: createdAt,
+				UpdatedAt: updatedAt,
+			}
 		})
 
-		It("returns only basic fields", func() {
-			result := router.buildPlaylist(ctx, playlist)
+		Context("with minimal client", func() {
+			BeforeEach(func() {
+				conf.Server.Subsonic.MinimalClients = "minimal-client"
+				player := model.Player{Client: "minimal-client"}
+				ctx = request.WithPlayer(ctx, player)
+			})
 
-			Expect(result.Id).To(Equal("pls-1"))
-			Expect(result.Name).To(Equal("My Playlist"))
-			Expect(result.SongCount).To(Equal(int32(10)))
-			Expect(result.Duration).To(Equal(int32(600)))
-			Expect(result.Created).To(Equal(playlist.CreatedAt))
-			Expect(result.Changed).To(Equal(playlist.UpdatedAt))
+			It("returns only basic fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
 
-			// These should not be set
-			Expect(result.Comment).To(BeEmpty())
-			Expect(result.Owner).To(BeEmpty())
-			Expect(result.Public).To(BeFalse())
-			Expect(result.CoverArt).To(BeEmpty())
+				Expect(result.Id).To(Equal("pls-1"))
+				Expect(result.Name).To(Equal("My Playlist"))
+				Expect(result.SongCount).To(Equal(int32(10)))
+				Expect(result.Duration).To(Equal(int32(600)))
+				Expect(result.Created).To(Equal(playlist.CreatedAt))
+				Expect(result.Changed).To(Equal(playlist.UpdatedAt))
+
+				// These should not be set
+				Expect(result.Comment).To(BeEmpty())
+				Expect(result.Owner).To(BeEmpty())
+				Expect(result.Public).To(BeFalse())
+				Expect(result.CoverArt).To(BeEmpty())
+			})
+		})
+
+		Context("with non-minimal client", func() {
+			BeforeEach(func() {
+				conf.Server.Subsonic.MinimalClients = "minimal-client"
+				player := model.Player{Client: "regular-client"}
+				ctx = request.WithPlayer(ctx, player)
+			})
+
+			It("returns all fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
+
+				Expect(result.Id).To(Equal("pls-1"))
+				Expect(result.Name).To(Equal("My Playlist"))
+				Expect(result.SongCount).To(Equal(int32(10)))
+				Expect(result.Duration).To(Equal(int32(600)))
+				Expect(result.Created).To(Equal(playlist.CreatedAt))
+				Expect(result.Changed).To(Equal(playlist.UpdatedAt))
+				Expect(result.Comment).To(Equal("Test comment"))
+				Expect(result.Owner).To(Equal("admin"))
+				Expect(result.Public).To(BeTrue())
+				Expect(result.Readonly).To(BeTrue())
+			})
+
+			It("returns all fields when as owner", func() {
+				ctx = request.WithUser(ctx, model.User{ID: "1234", UserName: "admin"})
+
+				result := router.buildPlaylist(ctx, playlist)
+
+				Expect(result.Id).To(Equal("pls-1"))
+				Expect(result.Name).To(Equal("My Playlist"))
+				Expect(result.SongCount).To(Equal(int32(10)))
+				Expect(result.Duration).To(Equal(int32(600)))
+				Expect(result.Created).To(Equal(playlist.CreatedAt))
+				Expect(result.Changed).To(Equal(playlist.UpdatedAt))
+				Expect(result.Comment).To(Equal("Test comment"))
+				Expect(result.Owner).To(Equal("admin"))
+				Expect(result.Public).To(BeTrue())
+				Expect(result.Readonly).To(BeFalse())
+			})
+		})
+
+		Context("when minimal clients list is empty", func() {
+			BeforeEach(func() {
+				conf.Server.Subsonic.MinimalClients = ""
+				player := model.Player{Client: "any-client"}
+				ctx = request.WithPlayer(ctx, player)
+			})
+
+			It("returns all fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
+
+				Expect(result.Comment).To(Equal("Test comment"))
+				Expect(result.Owner).To(Equal("admin"))
+				Expect(result.Public).To(BeTrue())
+			})
+		})
+
+		Context("when no player in context", func() {
+			It("returns all fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
+
+				Expect(result.Comment).To(Equal("Test comment"))
+				Expect(result.Owner).To(Equal("admin"))
+				Expect(result.Public).To(BeTrue())
+			})
 		})
 	})
 
-	Context("with non-minimal client", func() {
+	Describe("smart playlist", func() {
+		evaluatedAt := time.Date(2023, 2, 20, 15, 45, 0, 0, time.UTC)
+		validUntil := evaluatedAt.Add(5 * time.Second)
+
 		BeforeEach(func() {
-			conf.Server.Subsonic.MinimalClients = "minimal-client"
-			player := model.Player{Client: "regular-client"}
-			ctx = request.WithPlayer(ctx, player)
+			createdAt := time.Date(2023, 1, 15, 10, 30, 0, 0, time.UTC)
+			updatedAt := time.Date(2023, 2, 20, 14, 45, 0, 0, time.UTC)
+
+			playlist = model.Playlist{
+				ID:          "pls-1",
+				Name:        "My Playlist",
+				Comment:     "Test comment",
+				OwnerName:   "admin",
+				OwnerID:     "1234",
+				Public:      true,
+				SongCount:   10,
+				Duration:    600,
+				CreatedAt:   createdAt,
+				UpdatedAt:   updatedAt,
+				EvaluatedAt: &evaluatedAt,
+				Rules: &criteria.Criteria{
+					Expression: criteria.All{criteria.Contains{"title": "title"}},
+				},
+			}
 		})
 
-		It("returns all fields", func() {
-			result := router.buildPlaylist(ctx, playlist)
+		Context("with minimal client", func() {
+			BeforeEach(func() {
+				conf.Server.Subsonic.MinimalClients = "minimal-client"
+				player := model.Player{Client: "minimal-client"}
+				ctx = request.WithPlayer(ctx, player)
+			})
 
-			Expect(result.Id).To(Equal("pls-1"))
-			Expect(result.Name).To(Equal("My Playlist"))
-			Expect(result.SongCount).To(Equal(int32(10)))
-			Expect(result.Duration).To(Equal(int32(600)))
-			Expect(result.Created).To(Equal(playlist.CreatedAt))
-			Expect(result.Changed).To(Equal(playlist.UpdatedAt))
-			Expect(result.Comment).To(Equal("Test comment"))
-			Expect(result.Owner).To(Equal("admin"))
-			Expect(result.Public).To(BeTrue())
+			It("returns only basic fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
+
+				Expect(result.Id).To(Equal("pls-1"))
+				Expect(result.Name).To(Equal("My Playlist"))
+				Expect(result.SongCount).To(Equal(int32(10)))
+				Expect(result.Duration).To(Equal(int32(600)))
+				Expect(result.Created).To(Equal(playlist.CreatedAt))
+				Expect(result.Changed).To(Equal(evaluatedAt))
+
+				// These should not be set
+				Expect(result.Comment).To(BeEmpty())
+				Expect(result.Owner).To(BeEmpty())
+				Expect(result.Public).To(BeFalse())
+				Expect(result.CoverArt).To(BeEmpty())
+				Expect(result.OpenSubsonicPlaylist).To(BeNil())
+			})
+		})
+
+		Context("with non-minimal client", func() {
+			BeforeEach(func() {
+				conf.Server.Subsonic.MinimalClients = "minimal-client"
+				player := model.Player{Client: "regular-client"}
+				ctx = request.WithPlayer(ctx, player)
+			})
+
+			It("returns all fields", func() {
+				result := router.buildPlaylist(ctx, playlist)
+				Expect(result.Id).To(Equal("pls-1"))
+				Expect(result.Name).To(Equal("My Playlist"))
+				Expect(result.SongCount).To(Equal(int32(10)))
+				Expect(result.Duration).To(Equal(int32(600)))
+				Expect(result.Created).To(Equal(playlist.CreatedAt))
+				Expect(result.Changed).To(Equal(*playlist.EvaluatedAt))
+				Expect(result.Comment).To(Equal("Test comment"))
+				Expect(result.Owner).To(Equal("admin"))
+				Expect(result.Public).To(BeTrue())
+				Expect(result.Readonly).To(BeTrue())
+				Expect(result.ValidUntil).To(Equal(&validUntil))
+			})
 		})
 	})
-
-	Context("when minimal clients list is empty", func() {
-		BeforeEach(func() {
-			conf.Server.Subsonic.MinimalClients = ""
-			player := model.Player{Client: "any-client"}
-			ctx = request.WithPlayer(ctx, player)
-		})
-
-		It("returns all fields", func() {
-			result := router.buildPlaylist(ctx, playlist)
-
-			Expect(result.Comment).To(Equal("Test comment"))
-			Expect(result.Owner).To(Equal("admin"))
-			Expect(result.Public).To(BeTrue())
-		})
-	})
-
-	Context("when no player in context", func() {
-		It("returns all fields", func() {
-			result := router.buildPlaylist(ctx, playlist)
-
-			Expect(result.Comment).To(Equal("Test comment"))
-			Expect(result.Owner).To(Equal("admin"))
-			Expect(result.Public).To(BeTrue())
-		})
-	})
-
 })
 
 var _ = Describe("UpdatePlaylist", func() {
@@ -125,7 +224,7 @@ var _ = Describe("UpdatePlaylist", func() {
 	BeforeEach(func() {
 		ds = &tests.MockDataStore{}
 		playlists = &fakePlaylists{}
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, playlists, nil, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, playlists, nil, nil, nil, nil, nil)
 	})
 
 	It("clears the comment when parameter is empty", func() {

server/subsonic/responses/.snapshots/Responses Playlists with data should match .JSON

@@ -14,9 +14,20 @@
         "duration": 120,
         "public": true,
         "owner": "admin",
+        "created": "2023-02-20T14:45:00Z",
+        "changed": "2023-02-20T14:45:00Z",
+        "coverArt": "pl-123123123123",
+        "readonly": true,
+        "validUntil": "2023-02-20T14:45:00Z"
+      },
+      {
+        "id": "333",
+        "name": "ccc",
+        "songCount": 0,
+        "duration": 0,
         "created": "0001-01-01T00:00:00Z",
         "changed": "0001-01-01T00:00:00Z",
-        "coverArt": "pl-123123123123"
+        "readonly": false
       },
       {
         "id": "222",

server/subsonic/responses/.snapshots/Responses Playlists with data should match .XML

@@ -1,6 +1,7 @@
 <subsonic-response xmlns="http://subsonic.org/restapi" status="ok" version="1.16.1" type="navidrome" serverVersion="v0.55.0" openSubsonic="true">
   <playlists>
-    <playlist id="111" name="aaa" comment="comment" songCount="2" duration="120" public="true" owner="admin" created="0001-01-01T00:00:00Z" changed="0001-01-01T00:00:00Z" coverArt="pl-123123123123"></playlist>
+    <playlist id="111" name="aaa" comment="comment" songCount="2" duration="120" public="true" owner="admin" created="2023-02-20T14:45:00Z" changed="2023-02-20T14:45:00Z" coverArt="pl-123123123123" readonly="true" validUntil="2023-02-20T14:45:00Z"></playlist>
+    <playlist id="333" name="ccc" songCount="0" duration="0" created="0001-01-01T00:00:00Z" changed="0001-01-01T00:00:00Z"></playlist>
     <playlist id="222" name="bbb" songCount="0" duration="0" created="0001-01-01T00:00:00Z" changed="0001-01-01T00:00:00Z"></playlist>
   </playlists>
 </subsonic-response>

server/subsonic/responses/responses.go

@@ -61,6 +61,7 @@ type Subsonic struct {
 	OpenSubsonicExtensions *OpenSubsonicExtensions `xml:"openSubsonicExtensions,omitempty"  json:"openSubsonicExtensions,omitempty"`
 	LyricsList             *LyricsList             `xml:"lyricsList,omitempty"              json:"lyricsList,omitempty"`
 	PlayQueueByIndex       *PlayQueueByIndex       `xml:"playQueueByIndex,omitempty" json:"playQueueByIndex,omitempty"`
+	TranscodeDecision      *TranscodeDecision      `xml:"transcodeDecision,omitempty"       json:"transcodeDecision,omitempty"`
 }
 
 const (
@@ -298,16 +299,17 @@ type AlbumList2 struct {
 }
 
 type Playlist struct {
-	Id        string    `xml:"id,attr"                       json:"id"`
-	Name      string    `xml:"name,attr"                     json:"name"`
-	Comment   string    `xml:"comment,attr,omitempty"        json:"comment,omitempty"`
-	SongCount int32     `xml:"songCount,attr"                json:"songCount"`
-	Duration  int32     `xml:"duration,attr"                 json:"duration"`
-	Public    bool      `xml:"public,attr,omitempty"         json:"public,omitempty"`
-	Owner     string    `xml:"owner,attr,omitempty"          json:"owner,omitempty"`
-	Created   time.Time `xml:"created,attr"                  json:"created"`
-	Changed   time.Time `xml:"changed,attr"                  json:"changed"`
-	CoverArt  string    `xml:"coverArt,attr,omitempty"       json:"coverArt,omitempty"`
+	Id                    string    `xml:"id,attr"                       json:"id"`
+	Name                  string    `xml:"name,attr"                     json:"name"`
+	Comment               string    `xml:"comment,attr,omitempty"        json:"comment,omitempty"`
+	SongCount             int32     `xml:"songCount,attr"                json:"songCount"`
+	Duration              int32     `xml:"duration,attr"                 json:"duration"`
+	Public                bool      `xml:"public,attr,omitempty"         json:"public,omitempty"`
+	Owner                 string    `xml:"owner,attr,omitempty"          json:"owner,omitempty"`
+	Created               time.Time `xml:"created,attr"                  json:"created"`
+	Changed               time.Time `xml:"changed,attr"                  json:"changed"`
+	CoverArt              string    `xml:"coverArt,attr,omitempty"       json:"coverArt,omitempty"`
+	*OpenSubsonicPlaylist `xml:",omitempty" json:",omitempty"`
 	/*
 		<xs:sequence>
 		    <xs:element name="allowedUser" type="xs:string" minOccurs="0" maxOccurs="unbounded"/> <!--Added in 1.8.0-->
@@ -315,6 +317,11 @@ type Playlist struct {
 	*/
 }
 
+type OpenSubsonicPlaylist struct {
+	Readonly   bool       `xml:"readonly,attr,omitempty"   json:"readonly"`
+	ValidUntil *time.Time `xml:"validUntil,attr,omitempty" json:"validUntil,omitempty"`
+}
+
 type Playlists struct {
 	Playlist []Playlist `xml:"playlist"                           json:"playlist,omitempty"`
 }
@@ -611,3 +618,26 @@ func marshalJSONArray[T any](v []T) ([]byte, error) {
 	}
 	return json.Marshal(v)
 }
+
+// TranscodeDecision represents the response for getTranscodeDecision (OpenSubsonic transcoding extension)
+type TranscodeDecision struct {
+	CanDirectPlay    bool           `xml:"canDirectPlay,attr"               json:"canDirectPlay"`
+	CanTranscode     bool           `xml:"canTranscode,attr"                json:"canTranscode"`
+	TranscodeReasons []string       `xml:"transcodeReason,omitempty"        json:"transcodeReason,omitempty"`
+	ErrorReason      string         `xml:"errorReason,attr,omitempty"       json:"errorReason,omitempty"`
+	TranscodeParams  string         `xml:"transcodeParams,attr,omitempty"   json:"transcodeParams,omitempty"`
+	SourceStream     *StreamDetails `xml:"sourceStream,omitempty"           json:"sourceStream,omitempty"`
+	TranscodeStream  *StreamDetails `xml:"transcodeStream,omitempty"        json:"transcodeStream,omitempty"`
+}
+
+// StreamDetails describes audio stream properties for transcoding decisions
+type StreamDetails struct {
+	Protocol        string `xml:"protocol,attr,omitempty"        json:"protocol,omitempty"`
+	Container       string `xml:"container,attr,omitempty"       json:"container,omitempty"`
+	Codec           string `xml:"codec,attr,omitempty"           json:"codec,omitempty"`
+	AudioChannels   int32  `xml:"audioChannels,attr,omitempty"   json:"audioChannels,omitempty"`
+	AudioBitrate    int32  `xml:"audioBitrate,attr,omitempty"     json:"audioBitrate,omitempty"`
+	AudioProfile    string `xml:"audioProfile,attr,omitempty"    json:"audioProfile,omitempty"`
+	AudioSamplerate int32  `xml:"audioSamplerate,attr,omitempty" json:"audioSamplerate,omitempty"`
+	AudioBitdepth   int32  `xml:"audioBitdepth,attr,omitempty"   json:"audioBitdepth,omitempty"`
+}

server/subsonic/responses/responses_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/server/subsonic/responses"
 	. "github.com/navidrome/navidrome/server/subsonic/responses"
 	"github.com/navidrome/navidrome/utils/gg"
 	. "github.com/onsi/ginkgo/v2"
@@ -531,9 +532,9 @@ var _ = Describe("Responses", func() {
 		})
 
 		Context("with data", func() {
-			timestamp, _ := time.Parse(time.RFC3339, "2020-04-11T16:43:00Z04:00")
+			timestamp := time.Date(2023, 2, 20, 14, 45, 0, 0, time.UTC)
 			BeforeEach(func() {
-				pls := make([]Playlist, 2)
+				pls := make([]Playlist, 3)
 				pls[0] = Playlist{
 					Id:        "111",
 					Name:      "aaa",
@@ -545,8 +546,13 @@ var _ = Describe("Responses", func() {
 					CoverArt:  "pl-123123123123",
 					Created:   timestamp,
 					Changed:   timestamp,
+					OpenSubsonicPlaylist: &responses.OpenSubsonicPlaylist{
+						Readonly:   true,
+						ValidUntil: &timestamp,
+					},
 				}
-				pls[1] = Playlist{Id: "222", Name: "bbb"}
+				pls[1] = Playlist{Id: "333", Name: "ccc", OpenSubsonicPlaylist: &responses.OpenSubsonicPlaylist{}}
+				pls[2] = Playlist{Id: "222", Name: "bbb"}
 				response.Playlists.Playlist = pls
 			})
 

server/subsonic/searching_test.go

@@ -21,7 +21,7 @@ var _ = Describe("Search", func() {
 		ds = &tests.MockDataStore{}
 		auth.Init(ds)
 
-		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
 
 		// Get references to the mock repositories so we can inspect their Options
 		mockAlbumRepo = ds.Album(nil).(*tests.MockAlbumRepo)

server/subsonic/transcode.go

@@ -0,0 +1,349 @@
+package subsonic
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+
+	"github.com/navidrome/navidrome/core/transcode"
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/server/subsonic/responses"
+	"github.com/navidrome/navidrome/utils/req"
+)
+
+// API-layer request structs for JSON unmarshaling (decoupled from core structs)
+
+// clientInfoRequest represents client playback capabilities from the request body
+type clientInfoRequest struct {
+	Name                       string                  `json:"name,omitempty"`
+	Platform                   string                  `json:"platform,omitempty"`
+	MaxAudioBitrate            int                     `json:"maxAudioBitrate,omitempty"`
+	MaxTranscodingAudioBitrate int                     `json:"maxTranscodingAudioBitrate,omitempty"`
+	DirectPlayProfiles         []directPlayProfileReq  `json:"directPlayProfiles,omitempty"`
+	TranscodingProfiles        []transcodingProfileReq `json:"transcodingProfiles,omitempty"`
+	CodecProfiles              []codecProfileReq       `json:"codecProfiles,omitempty"`
+}
+
+// directPlayProfileReq describes a format the client can play directly
+type directPlayProfileReq struct {
+	Containers       []string `json:"containers,omitempty"`
+	AudioCodecs      []string `json:"audioCodecs,omitempty"`
+	Protocols        []string `json:"protocols,omitempty"`
+	MaxAudioChannels int      `json:"maxAudioChannels,omitempty"`
+}
+
+// transcodingProfileReq describes a transcoding target the client supports
+type transcodingProfileReq struct {
+	Container        string `json:"container,omitempty"`
+	AudioCodec       string `json:"audioCodec,omitempty"`
+	Protocol         string `json:"protocol,omitempty"`
+	MaxAudioChannels int    `json:"maxAudioChannels,omitempty"`
+}
+
+// codecProfileReq describes codec-specific limitations
+type codecProfileReq struct {
+	Type        string          `json:"type,omitempty"`
+	Name        string          `json:"name,omitempty"`
+	Limitations []limitationReq `json:"limitations,omitempty"`
+}
+
+// limitationReq describes a specific codec limitation
+type limitationReq struct {
+	Name       string   `json:"name,omitempty"`
+	Comparison string   `json:"comparison,omitempty"`
+	Values     []string `json:"values,omitempty"`
+	Required   bool     `json:"required,omitempty"`
+}
+
+// toCoreClientInfo converts the API request struct to the transcode.ClientInfo struct.
+// The OpenSubsonic spec uses bps for bitrate values; core uses kbps.
+func (r *clientInfoRequest) toCoreClientInfo() *transcode.ClientInfo {
+	ci := &transcode.ClientInfo{
+		Name:                       r.Name,
+		Platform:                   r.Platform,
+		MaxAudioBitrate:            bpsToKbps(r.MaxAudioBitrate),
+		MaxTranscodingAudioBitrate: bpsToKbps(r.MaxTranscodingAudioBitrate),
+	}
+
+	for _, dp := range r.DirectPlayProfiles {
+		ci.DirectPlayProfiles = append(ci.DirectPlayProfiles, transcode.DirectPlayProfile{
+			Containers:       dp.Containers,
+			AudioCodecs:      dp.AudioCodecs,
+			Protocols:        dp.Protocols,
+			MaxAudioChannels: dp.MaxAudioChannels,
+		})
+	}
+
+	for _, tp := range r.TranscodingProfiles {
+		ci.TranscodingProfiles = append(ci.TranscodingProfiles, transcode.Profile{
+			Container:        tp.Container,
+			AudioCodec:       tp.AudioCodec,
+			Protocol:         tp.Protocol,
+			MaxAudioChannels: tp.MaxAudioChannels,
+		})
+	}
+
+	for _, cp := range r.CodecProfiles {
+		coreCP := transcode.CodecProfile{
+			Type: cp.Type,
+			Name: cp.Name,
+		}
+		for _, lim := range cp.Limitations {
+			coreLim := transcode.Limitation{
+				Name:       lim.Name,
+				Comparison: lim.Comparison,
+				Values:     lim.Values,
+				Required:   lim.Required,
+			}
+			// Convert audioBitrate limitation values from bps to kbps
+			if lim.Name == transcode.LimitationAudioBitrate {
+				coreLim.Values = convertBitrateValues(lim.Values)
+			}
+			coreCP.Limitations = append(coreCP.Limitations, coreLim)
+		}
+		ci.CodecProfiles = append(ci.CodecProfiles, coreCP)
+	}
+
+	return ci
+}
+
+// bpsToKbps converts bits per second to kilobits per second.
+func bpsToKbps(bps int) int {
+	return bps / 1000
+}
+
+// kbpsToBps converts kilobits per second to bits per second.
+func kbpsToBps(kbps int) int {
+	return kbps * 1000
+}
+
+// convertBitrateValues converts a slice of bps string values to kbps string values.
+func convertBitrateValues(bpsValues []string) []string {
+	result := make([]string, len(bpsValues))
+	for i, v := range bpsValues {
+		n, err := strconv.Atoi(v)
+		if err == nil {
+			result[i] = strconv.Itoa(n / 1000)
+		} else {
+			result[i] = v // preserve unparseable values as-is
+		}
+	}
+	return result
+}
+
+// validate checks that all enum fields in the request contain valid values per the OpenSubsonic spec.
+func (r *clientInfoRequest) validate() error {
+	for _, dp := range r.DirectPlayProfiles {
+		for _, p := range dp.Protocols {
+			if !isValidProtocol(p) {
+				return fmt.Errorf("invalid protocol: %s", p)
+			}
+		}
+	}
+	for _, tp := range r.TranscodingProfiles {
+		if tp.Protocol != "" && !isValidProtocol(tp.Protocol) {
+			return fmt.Errorf("invalid protocol: %s", tp.Protocol)
+		}
+	}
+	for _, cp := range r.CodecProfiles {
+		if !isValidCodecProfileType(cp.Type) {
+			return fmt.Errorf("invalid codec profile type: %s", cp.Type)
+		}
+		for _, lim := range cp.Limitations {
+			if !isValidLimitationName(lim.Name) {
+				return fmt.Errorf("invalid limitation name: %s", lim.Name)
+			}
+			if !isValidComparison(lim.Comparison) {
+				return fmt.Errorf("invalid comparison: %s", lim.Comparison)
+			}
+		}
+	}
+	return nil
+}
+
+func isValidProtocol(p string) bool {
+	return p == transcode.ProtocolHTTP || p == transcode.ProtocolHLS
+}
+
+func isValidCodecProfileType(t string) bool {
+	return t == transcode.CodecProfileTypeAudio
+}
+
+func isValidLimitationName(n string) bool {
+	return n == transcode.LimitationAudioChannels ||
+		n == transcode.LimitationAudioBitrate ||
+		n == transcode.LimitationAudioProfile ||
+		n == transcode.LimitationAudioSamplerate ||
+		n == transcode.LimitationAudioBitdepth
+}
+
+func isValidComparison(c string) bool {
+	return c == transcode.ComparisonEquals ||
+		c == transcode.ComparisonNotEquals ||
+		c == transcode.ComparisonLessThanEqual ||
+		c == transcode.ComparisonGreaterThanEqual
+}
+
+// GetTranscodeDecision handles the OpenSubsonic getTranscodeDecision endpoint.
+// It receives client capabilities and returns a decision on whether to direct play or transcode.
+func (api *Router) GetTranscodeDecision(w http.ResponseWriter, r *http.Request) (*responses.Subsonic, error) {
+	if r.Method != http.MethodPost {
+		w.Header().Set("Allow", "POST")
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		return nil, nil
+	}
+
+	ctx := r.Context()
+	p := req.Params(r)
+
+	mediaID, err := p.String("mediaId")
+	if err != nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required parameter: mediaId")
+	}
+
+	mediaType, err := p.String("mediaType")
+	if err != nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required parameter: mediaType")
+	}
+
+	// Only support songs for now
+	if mediaType != "song" {
+		return nil, newError(responses.ErrorGeneric, "mediaType '%s' is not yet supported", mediaType)
+	}
+
+	// Parse and validate ClientInfo from request body (required per OpenSubsonic spec)
+	var clientInfoReq clientInfoRequest
+	if r.Body == nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required JSON request body")
+	}
+	if err := json.NewDecoder(r.Body).Decode(&clientInfoReq); err != nil {
+		return nil, newError(responses.ErrorGeneric, "invalid JSON request body")
+	}
+	if err := clientInfoReq.validate(); err != nil {
+		return nil, newError(responses.ErrorGeneric, "%v", err)
+	}
+	clientInfo := clientInfoReq.toCoreClientInfo()
+
+	// Get media file
+	mf, err := api.ds.MediaFile(ctx).Get(mediaID)
+	if err != nil {
+		return nil, newError(responses.ErrorDataNotFound, "media file not found: %s", mediaID)
+	}
+
+	// Make the decision
+	decision, err := api.transcodeDecision.MakeDecision(ctx, mf, clientInfo)
+	if err != nil {
+		return nil, newError(responses.ErrorGeneric, "failed to make transcode decision: %v", err)
+	}
+
+	// Create transcode params token
+	transcodeParams, err := api.transcodeDecision.CreateTranscodeParams(decision)
+	if err != nil {
+		return nil, newError(responses.ErrorGeneric, "failed to create transcode token: %v", err)
+	}
+
+	// Build response (convert kbps from core to bps for the API)
+	response := newResponse()
+	response.TranscodeDecision = &responses.TranscodeDecision{
+		CanDirectPlay:    decision.CanDirectPlay,
+		CanTranscode:     decision.CanTranscode,
+		TranscodeReasons: decision.TranscodeReasons,
+		ErrorReason:      decision.ErrorReason,
+		TranscodeParams:  transcodeParams,
+		SourceStream: &responses.StreamDetails{
+			Protocol:        "http",
+			Container:       decision.SourceStream.Container,
+			Codec:           decision.SourceStream.Codec,
+			AudioBitrate:    int32(kbpsToBps(decision.SourceStream.Bitrate)),
+			AudioProfile:    decision.SourceStream.Profile,
+			AudioSamplerate: int32(decision.SourceStream.SampleRate),
+			AudioBitdepth:   int32(decision.SourceStream.BitDepth),
+			AudioChannels:   int32(decision.SourceStream.Channels),
+		},
+	}
+
+	if decision.TranscodeStream != nil {
+		response.TranscodeDecision.TranscodeStream = &responses.StreamDetails{
+			Protocol:        "http",
+			Container:       decision.TranscodeStream.Container,
+			Codec:           decision.TranscodeStream.Codec,
+			AudioBitrate:    int32(kbpsToBps(decision.TranscodeStream.Bitrate)),
+			AudioProfile:    decision.TranscodeStream.Profile,
+			AudioSamplerate: int32(decision.TranscodeStream.SampleRate),
+			AudioBitdepth:   int32(decision.TranscodeStream.BitDepth),
+			AudioChannels:   int32(decision.TranscodeStream.Channels),
+		}
+	}
+
+	return response, nil
+}
+
+// GetTranscodeStream handles the OpenSubsonic getTranscodeStream endpoint.
+// It streams media using the decision encoded in the transcodeParams JWT token.
+func (api *Router) GetTranscodeStream(w http.ResponseWriter, r *http.Request) (*responses.Subsonic, error) {
+	ctx := r.Context()
+	p := req.Params(r)
+
+	mediaID, err := p.String("mediaId")
+	if err != nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required parameter: mediaId")
+	}
+
+	mediaType, err := p.String("mediaType")
+	if err != nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required parameter: mediaType")
+	}
+
+	transcodeParams, err := p.String("transcodeParams")
+	if err != nil {
+		return nil, newError(responses.ErrorMissingParameter, "missing required parameter: transcodeParams")
+	}
+
+	// Only support songs for now
+	if mediaType != "song" {
+		return nil, newError(responses.ErrorGeneric, "mediaType '%s' is not yet supported", mediaType)
+	}
+
+	// Parse and validate the token
+	params, err := api.transcodeDecision.ParseTranscodeParams(transcodeParams)
+	if err != nil {
+		log.Warn(ctx, "Failed to parse transcode token", err)
+		return nil, newError(responses.ErrorDataNotFound, "invalid or expired transcodeParams token")
+	}
+
+	// Verify mediaId matches token
+	if params.MediaID != mediaID {
+		return nil, newError(responses.ErrorDataNotFound, "mediaId does not match token")
+	}
+
+	// Determine streaming parameters
+	format := ""
+	maxBitRate := 0
+	if !params.DirectPlay && params.TargetFormat != "" {
+		format = params.TargetFormat
+		maxBitRate = params.TargetBitrate // Already in kbps, matching the streamer
+	}
+
+	// Get offset parameter
+	offset := p.IntOr("offset", 0)
+
+	// Create stream
+	stream, err := api.streamer.NewStream(ctx, mediaID, format, maxBitRate, offset)
+	if err != nil {
+		return nil, err
+	}
+
+	// Make sure the stream will be closed at the end
+	defer func() {
+		if err := stream.Close(); err != nil && log.IsGreaterOrEqualTo(log.LevelDebug) {
+			log.Error("Error closing stream", "id", mediaID, "file", stream.Name(), err)
+		}
+	}()
+
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+
+	api.serveStream(ctx, w, r, stream, mediaID)
+
+	return nil, nil
+}

server/subsonic/transcode_test.go

@@ -0,0 +1,268 @@
+package subsonic
+
+import (
+	"bytes"
+	"context"
+	"net/http"
+	"net/http/httptest"
+
+	"github.com/navidrome/navidrome/core/transcode"
+	"github.com/navidrome/navidrome/model"
+	"github.com/navidrome/navidrome/tests"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Transcode endpoints", func() {
+	var (
+		router     *Router
+		ds         *tests.MockDataStore
+		mockTD     *mockTranscodeDecision
+		w          *httptest.ResponseRecorder
+		mockMFRepo *tests.MockMediaFileRepo
+	)
+
+	BeforeEach(func() {
+		mockMFRepo = &tests.MockMediaFileRepo{}
+		ds = &tests.MockDataStore{MockedMediaFile: mockMFRepo}
+		mockTD = &mockTranscodeDecision{}
+		router = New(ds, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, mockTD)
+		w = httptest.NewRecorder()
+	})
+
+	Describe("GetTranscodeDecision", func() {
+		It("returns 405 for non-POST requests", func() {
+			r := newGetRequest("mediaId=123", "mediaType=song")
+			resp, err := router.GetTranscodeDecision(w, r)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(resp).To(BeNil())
+			Expect(w.Code).To(Equal(http.StatusMethodNotAllowed))
+			Expect(w.Header().Get("Allow")).To(Equal("POST"))
+		})
+
+		It("returns error when mediaId is missing", func() {
+			r := newJSONPostRequest("mediaType=song", "{}")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error when mediaType is missing", func() {
+			r := newJSONPostRequest("mediaId=123", "{}")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error for unsupported mediaType", func() {
+			r := newJSONPostRequest("mediaId=123&mediaType=podcast", "{}")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("not yet supported"))
+		})
+
+		It("returns error when media file not found", func() {
+			mockMFRepo.SetError(true)
+			r := newJSONPostRequest("mediaId=notfound&mediaType=song", "{}")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error when body is empty", func() {
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", "")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error when body contains invalid JSON", func() {
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", "not-json{{{")
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error for invalid protocol in direct play profile", func() {
+			body := `{"directPlayProfiles":[{"containers":["mp3"],"audioCodecs":["mp3"],"protocols":["ftp"]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid protocol"))
+		})
+
+		It("returns error for invalid comparison operator", func() {
+			body := `{"codecProfiles":[{"type":"AudioCodec","name":"mp3","limitations":[{"name":"audioBitrate","comparison":"InvalidOp","values":["320"]}]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid comparison"))
+		})
+
+		It("returns error for invalid limitation name", func() {
+			body := `{"codecProfiles":[{"type":"AudioCodec","name":"mp3","limitations":[{"name":"unknownField","comparison":"Equals","values":["320"]}]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid limitation name"))
+		})
+
+		It("returns error for invalid codec profile type", func() {
+			body := `{"codecProfiles":[{"type":"VideoCodec","name":"mp3"}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid codec profile type"))
+		})
+
+		It("rejects wrong-case protocol", func() {
+			body := `{"directPlayProfiles":[{"containers":["mp3"],"audioCodecs":["mp3"],"protocols":["HTTP"]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid protocol"))
+		})
+
+		It("rejects wrong-case codec profile type", func() {
+			body := `{"codecProfiles":[{"type":"audiocodec","name":"mp3"}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid codec profile type"))
+		})
+
+		It("rejects wrong-case comparison operator", func() {
+			body := `{"codecProfiles":[{"type":"AudioCodec","name":"mp3","limitations":[{"name":"audioBitrate","comparison":"lessthanequal","values":["320"]}]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid comparison"))
+		})
+
+		It("rejects wrong-case limitation name", func() {
+			body := `{"codecProfiles":[{"type":"AudioCodec","name":"mp3","limitations":[{"name":"AudioBitrate","comparison":"Equals","values":["320"]}]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			_, err := router.GetTranscodeDecision(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("invalid limitation name"))
+		})
+
+		It("returns a valid decision response", func() {
+			mockMFRepo.SetData(model.MediaFiles{
+				{ID: "song-1", Suffix: "mp3", Codec: "MP3", BitRate: 320, Channels: 2, SampleRate: 44100},
+			})
+			mockTD.decision = &transcode.Decision{
+				MediaID:       "song-1",
+				CanDirectPlay: true,
+				SourceStream: transcode.StreamDetails{
+					Container: "mp3", Codec: "mp3", Bitrate: 320,
+					SampleRate: 44100, Channels: 2,
+				},
+			}
+			mockTD.token = "test-jwt-token"
+
+			body := `{"directPlayProfiles":[{"containers":["mp3"],"protocols":["http"]}]}`
+			r := newJSONPostRequest("mediaId=song-1&mediaType=song", body)
+			resp, err := router.GetTranscodeDecision(w, r)
+
+			Expect(err).ToNot(HaveOccurred())
+			Expect(resp.TranscodeDecision).ToNot(BeNil())
+			Expect(resp.TranscodeDecision.CanDirectPlay).To(BeTrue())
+			Expect(resp.TranscodeDecision.TranscodeParams).To(Equal("test-jwt-token"))
+			Expect(resp.TranscodeDecision.SourceStream).ToNot(BeNil())
+			Expect(resp.TranscodeDecision.SourceStream.Protocol).To(Equal("http"))
+			Expect(resp.TranscodeDecision.SourceStream.Container).To(Equal("mp3"))
+			Expect(resp.TranscodeDecision.SourceStream.AudioBitrate).To(Equal(int32(320_000)))
+		})
+
+		It("includes transcode stream when transcoding", func() {
+			mockMFRepo.SetData(model.MediaFiles{
+				{ID: "song-2", Suffix: "flac", Codec: "FLAC", BitRate: 1000, Channels: 2, SampleRate: 96000, BitDepth: 24},
+			})
+			mockTD.decision = &transcode.Decision{
+				MediaID:          "song-2",
+				CanDirectPlay:    false,
+				CanTranscode:     true,
+				TargetFormat:     "mp3",
+				TargetBitrate:    256,
+				TranscodeReasons: []string{"container not supported"},
+				SourceStream: transcode.StreamDetails{
+					Container: "flac", Codec: "flac", Bitrate: 1000,
+					SampleRate: 96000, BitDepth: 24, Channels: 2,
+				},
+				TranscodeStream: &transcode.StreamDetails{
+					Container: "mp3", Codec: "mp3", Bitrate: 256,
+					SampleRate: 96000, Channels: 2,
+				},
+			}
+			mockTD.token = "transcode-token"
+
+			r := newJSONPostRequest("mediaId=song-2&mediaType=song", "{}")
+			resp, err := router.GetTranscodeDecision(w, r)
+
+			Expect(err).ToNot(HaveOccurred())
+			Expect(resp.TranscodeDecision.CanTranscode).To(BeTrue())
+			Expect(resp.TranscodeDecision.TranscodeReasons).To(ConsistOf("container not supported"))
+			Expect(resp.TranscodeDecision.TranscodeStream).ToNot(BeNil())
+			Expect(resp.TranscodeDecision.TranscodeStream.Container).To(Equal("mp3"))
+		})
+	})
+
+	Describe("GetTranscodeStream", func() {
+		It("returns error when mediaId is missing", func() {
+			r := newGetRequest("mediaType=song", "transcodeParams=abc")
+			_, err := router.GetTranscodeStream(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error when transcodeParams is missing", func() {
+			r := newGetRequest("mediaId=123", "mediaType=song")
+			_, err := router.GetTranscodeStream(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error for invalid token", func() {
+			mockTD.parseErr = model.ErrNotFound
+			r := newGetRequest("mediaId=123", "mediaType=song", "transcodeParams=bad-token")
+			_, err := router.GetTranscodeStream(w, r)
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("returns error when mediaId doesn't match token", func() {
+			mockTD.params = &transcode.Params{MediaID: "other-id", DirectPlay: true}
+			r := newGetRequest("mediaId=wrong-id", "mediaType=song", "transcodeParams=valid-token")
+			_, err := router.GetTranscodeStream(w, r)
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("does not match"))
+		})
+	})
+})
+
+// newJSONPostRequest creates an HTTP POST request with JSON body and query params
+func newJSONPostRequest(queryParams string, jsonBody string) *http.Request {
+	r := httptest.NewRequest("POST", "/getTranscodeDecision?"+queryParams, bytes.NewBufferString(jsonBody))
+	r.Header.Set("Content-Type", "application/json")
+	return r
+}
+
+// mockTranscodeDecision is a test double for core.TranscodeDecision
+type mockTranscodeDecision struct {
+	decision *transcode.Decision
+	token    string
+	tokenErr error
+	params   *transcode.Params
+	parseErr error
+}
+
+func (m *mockTranscodeDecision) MakeDecision(_ context.Context, _ *model.MediaFile, _ *transcode.ClientInfo) (*transcode.Decision, error) {
+	if m.decision != nil {
+		return m.decision, nil
+	}
+	return &transcode.Decision{}, nil
+}
+
+func (m *mockTranscodeDecision) CreateTranscodeParams(_ *transcode.Decision) (string, error) {
+	return m.token, m.tokenErr
+}
+
+func (m *mockTranscodeDecision) ParseTranscodeParams(_ string) (*transcode.Params, error) {
+	if m.parseErr != nil {
+		return nil, m.parseErr
+	}
+	return m.params, nil
+}

tests/mock_mediafile_repo.go

@@ -44,16 +44,12 @@ func (m *MockMediaFileRepo) SetData(mfs model.MediaFiles) {
 	}
 }
 
-func (m *MockMediaFileRepo) Exists(ids ...string) (bool, error) {
+func (m *MockMediaFileRepo) Exists(id string) (bool, error) {
 	if m.Err {
 		return false, errors.New("error")
 	}
-	for _, id := range ids {
-		if _, found := m.Data[id]; !found {
-			return false, nil
-		}
-	}
-	return true, nil
+	_, found := m.Data[id]
+	return found, nil
 }
 
 func (m *MockMediaFileRepo) Get(id string) (*model.MediaFile, error) {