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LocalAI/docs/content/features
Ettore Di Giacinto b93e7bdfb3 fix(audio-transform): reject extensible WAV from the passthrough, escape stem URLs, convert stems with dst
Four fixes from the second review, plus one bug they made visible.

isPCM16Wav tested only the bit depth, and go-audio's IsValidFile never looks at
the format tag, so a 16-bit WAVE_FORMAT_EXTENSIBLE (0xFFFE) upload was passed
through untouched where the old fold would have transcoded it. audio.cpp's WAV
reader accepts 16-bit only when the tag is 1, so such a file died with
"unsupported WAV encoding". Extensible is what many DAWs and Windows tools
write and music files are this endpoint's new headline input, so it is a
first-contact failure rather than a corner. The check now requires tag 1, with a
spec that fails against the old implementation.

Stem URLs are percent-escaped. A stem name is the model's own string and legally
contains a space, a '#', a '?' or a '%'; an unescaped '#' truncates the URL
before the request is even sent. The name field keeps the raw name.

sample_rate and response_format are applied to the stems as well as to dst.
Applying beat documenting: dst IS one of those stems, so leaving them alone
broke the "dst duplicates the selected stem" invariant the whole design rests
on, and both conversions are no-ops when unset. A stem whose conversion fails is
dropped from the header rather than advertised in the wrong shape.

Verifying that turned up why it had never been noticed: the two fields were
never bound at all. The request arrives as multipart/form-data and echo's binder
falls back to the FIELD NAME without a form tag, matching only
case-insensitively, so "SampleRate" never matched "sample_rate" and "Format"
never matched "response_format". Both were documented in the endpoint table and
silently ignored. Two form tags fix it, and with them the conversion is
observable end to end.

Docs: audio-transform.md now documents what LocalAI does to an upload before the
backend sees it, which backend gets the 16 kHz mono fold and why, params[stem],
and the X-Audio-Stems header with a worked example.

Also records the known limitation that the fold lookup is on the bare backend
name, so pinned variants (vulkan-localvqe) do not match, and points at
IsLlamaCppBackend as the suffix-tolerant precedent.

Assisted-by: Claude:claude-opus-5 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
2026-07-26 18:51:56 +00:00
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