* feat: export as MP4 (karaoke video) for MP4 uploads and YouTube (#219)
Add an MP4 export that muxes the current mixer state (e.g. vocals muted)
with the source video, producing a karaoke-style video.
Backend:
- Preserve a silent video.mp4 from .mp4 uploads (stream-copy, no re-encode).
- YouTube jobs do a best-effort video-only download (H.264/avc1, <=720p)
to video.mp4, decoupled from the audio source so failures degrade to
audio-only. New STEMDECK_VIDEO_MAX_HEIGHT config.
- GET /api/jobs/{id}/video.mp4 streams a fragmented MP4: the amix audio
graph encoded as AAC, video stream-copied.
- has_video flag on Job, surfaced in state and persisted to metadata.
Frontend:
- MP4 added as a fourth export format (WAV/MP3/FLAC/MP4), shown only for
jobs with a preserved video track. In MP4 mode, Export Mix produces the
karaoke video and the audio-only Stems/Region rows are hidden.
SoundCloud and plain audio uploads are audio-only (no MP4 option).
* feat: bundle FFmpeg on Linux via first-launch download
Linux no longer requires `sudo apt install ffmpeg`. The desktop shell now
downloads a static FFmpeg build into the user data dir on first launch
(like Windows/macOS), falling back to a system ffmpeg on PATH when present.
This also fixes Demucs failing to decode compressed sources, since the
download lands in data_dir/ffmpeg which config.json already adds to PATH.
- ensure_ffmpeg: prefer a system ffmpeg, else download_linux_ffmpeg.
- download_linux_ffmpeg: fetch the .tar.xz, extract with system tar,
copy ffmpeg + ffprobe into data_dir/ffmpeg. STEMDECK_FFMPEG_URL overrides.
- Widen download_file and make_executable from macos to unix so Linux
reuses them.
- Not bundled in the tarball, so we don't redistribute FFmpeg.
- Update Linux README/notices/packaging comment to drop the ffmpeg apt step.
* style: apply ruff format to MP4 export code
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Co-authored-by: Thales <>
Tha.Les
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