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ee64c3b116
`muxVideoWithAudio` passed `-avoid_negative_ts make_zero` unless the caller
set `preserveAudioPrimingEditList`. In practice the dominant path is an AAC
sidecar copied into mp4, where that flag is actively harmful: ffmpeg's
default is `auto`, which the mp4/mov muxers (AVFMT_TS_NEGATIVE) already
resolve to `disabled`. Forcing `make_zero` overrides the correct default,
discards the priming edit list the sidecar encode created, shifts the video
start_time forward by one AAC frame and writes an empty video edit at t=0 —
which edit-list-honoring players (QuickTime/Safari) render as a black first
frame.
Verified with ffprobe on a copy mux of a 30fps h264 mp4 and an AAC sidecar:
with `make_zero` video start_time 0.066000, elst: [media time -1,
dur 5940] + [media time 6000, dur 180000]
audio start_time 0.042993, elst: [media time -1, ...]
without (this fix) video start_time 0.000000, elst: [media time 6000,
dur 180000]
audio start_time 0.000000, elst: [media time 1024, ...]
The empty leading edit and the offset both disappear, and the audio keeps
its 1024-sample priming edit.
The flag is now never passed for a mux, in any mode. `preserveAudioPrimingEditList`
is part of the exported engine API, so it stays on `MuxVideoWithAudioOptions`
as `@deprecated` and no-op rather than being removed; the two internal callers
that set it (`assembleStage`, distributed `assemble`) drop it.
`buildEncoderArgs` and `streamingEncoder` still pass the flag for video-only
output and are deliberately left alone — those chunks are consumed as
intermediates, not as a delivered mp4/mov.
Fixes #3487
Co-authored-by: Alexandru Mincu <alex@mountsoftware.ro>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>