LocalAI/core/http/endpoints/localai/tts.go

package localai

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"path/filepath"

	"github.com/labstack/echo/v4"
	"github.com/mudler/LocalAI/core/backend"
	"github.com/mudler/LocalAI/core/config"
	"github.com/mudler/LocalAI/core/http/middleware"
	"github.com/mudler/LocalAI/core/schema"
	"github.com/mudler/LocalAI/core/services/voiceprofile"
	"github.com/mudler/LocalAI/pkg/audio"
	"github.com/mudler/LocalAI/pkg/model"
	"github.com/mudler/LocalAI/pkg/utils"
	"github.com/mudler/xlog"
)

// TTSEndpoint is the OpenAI Speech API endpoint https://platform.openai.com/docs/api-reference/audio/createSpeech
//
//		@Summary	Generates audio from the input text.
//		@Tags		audio
//	 	@Accept json
//	 	@Produce audio/x-wav
//		@Param		request	body		schema.TTSRequest	true	"query params"
//		@Success	200		{string}	binary				"generated audio/wav file"
//		@Router		/v1/audio/speech [post]
//		@Router		/tts [post]
func TTSEndpoint(cl *config.ModelConfigLoader, ml *model.ModelLoader, appConfig *config.ApplicationConfig, profiles *voiceprofile.Store) echo.HandlerFunc {
	return func(c echo.Context) error {
		input, ok := c.Get(middleware.CONTEXT_LOCALS_KEY_LOCALAI_REQUEST).(*schema.TTSRequest)
		if !ok || input.Model == "" {
			return echo.ErrBadRequest
		}

		cfg, ok := c.Get(middleware.CONTEXT_LOCALS_KEY_MODEL_CONFIG).(*config.ModelConfig)
		if !ok || cfg == nil {
			return echo.ErrBadRequest
		}

		if err := applyTTSSpeed(input); err != nil {
			return err
		}

		xlog.Debug("LocalAI TTS Request received", "model", input.Model)

		if cfg.Backend == "" && input.Backend != "" {
			cfg.Backend = input.Backend
		}

		if input.Language != "" {
			cfg.Language = input.Language
		}

		if input.Voice != "" {
			cfg.Voice = input.Voice
			if voiceprofile.IsReference(input.Voice) {
				profileID, valid := voiceprofile.ParseReference(input.Voice)
				if !valid {
					return echo.NewHTTPError(http.StatusBadRequest, "invalid voice profile reference")
				}
				if config.VoiceCloningForModel(cfg) == nil {
					return echo.NewHTTPError(http.StatusBadRequest, "selected model does not support reference-audio voice cloning")
				}
				if profiles == nil {
					return echo.NewHTTPError(http.StatusInternalServerError, "voice profile store is unavailable")
				}
				profile, referencePaths, release, err := profiles.LeaseAudios(c.Request().Context(), profileID)
				if err != nil {
					if errors.Is(err, voiceprofile.ErrNotFound) {
						return echo.NewHTTPError(http.StatusNotFound, "voice profile not found")
					}
					return fmt.Errorf("resolve voice profile: %w", err)
				}
				defer release()
				cfg.Voice = referencePaths[0]
				if cfg.Language == "" && profile.Language != "" {
					cfg.Language = profile.Language
				}
				if input.Params == nil {
					input.Params = make(map[string]string)
				}
				input.Params["ref_text"] = profile.Transcript
				if supportsMultipleVoiceReferences(cfg.Backend) && len(referencePaths) > 1 {
					references := make([]map[string]string, 0, len(referencePaths))
					for index, path := range referencePaths {
						references = append(references, map[string]string{"audio": path, "text": profile.References[index].Transcript})
					}
					encoded, err := json.Marshal(references)
					if err != nil {
						return fmt.Errorf("encode voice profile references: %w", err)
					}
					input.Params["multi_reference_cond"] = string(encoded)
					if cfg.Backend == "audio-cpp" {
						cfg.Voice = ""
					}
				}
				xlog.Debug("Resolved saved voice profile", "id", profile.ID, "model", input.Model)
			}
		}

		// Handle streaming TTS
		if input.Stream {
			// Set headers for streaming audio
			c.Response().Header().Set("Content-Type", "audio/wav")
			c.Response().Header().Set("Transfer-Encoding", "chunked")
			c.Response().Header().Set("Cache-Control", "no-cache")
			c.Response().Header().Set("Connection", "keep-alive")

			// Stream audio chunks as they're generated
			err := backend.ModelTTSStream(c.Request().Context(), input.Input, cfg.Voice, cfg.Language, input.Instructions, input.Params, ml, appConfig, *cfg, func(audioChunk []byte) error {
				_, writeErr := c.Response().Write(audioChunk)
				if writeErr != nil {
					return writeErr
				}
				c.Response().Flush()
				return nil
			})
			if err != nil {
				return err
			}

			return nil
		}

		// Non-streaming TTS (existing behavior)
		filePath, _, err := backend.ModelTTS(c.Request().Context(), input.Input, cfg.Voice, cfg.Language, input.Instructions, input.Params, ml, appConfig, *cfg)
		if err != nil {
			return err
		}

		// Resample to requested sample rate if specified
		if input.SampleRate > 0 {
			filePath, err = utils.AudioResample(filePath, input.SampleRate)
			if err != nil {
				return err
			}
		}

		// Convert generated file to target format
		filePath, err = utils.AudioConvert(filePath, input.Format)
		if err != nil {
			return err
		}

		filePath, contentType := audio.NormalizeAudioFile(filePath)
		if contentType != "" {
			c.Response().Header().Set("Content-Type", contentType)
		}
		return c.Attachment(filePath, filepath.Base(filePath))
	}
}

func supportsMultipleVoiceReferences(backendName string) bool {
	return backendName == "fish-speech" || backendName == "audio-cpp"
}