I had been discarding FFmpeg's stderr with Stdio::null(). It says exactly
what happens: an unimplemented "Reserved bit", then a negative bit-skip --
and the failing frame index is always the last one.
bank packets frames fr/packet fails at
VOICE_D_450 8 45.7 5.71 44
VOICE_D_452 7 29.4 4.21 28
VOICE_D_453 22 198.9 9.04 198
VOICE_D_454 29 287.5 9.92 287
So the previous entry's "the decodes are visibly partial" is wrong, and it
was mine. I read "samples per input byte ranges 2.10-4.96" as truncation; it
is ordinary XMA1 variable bitrate. Only the final frame of each stream is
lost. The decode is essentially complete.
The sample rate still does not converge. I tried the obvious repair --
counting the whole bank, leading region plus RIFF sub-waves, since the two
split the audio very differently per bank. Two banks then agreed at a tidy
~2.1x ratio pointing near 22 kHz, and the third refuted it: implied rates are
39742, 20563 and 23108 Hz.
So the container is identified, the decode is essentially complete, and the
duration still does not reconcile -- which moves suspicion to the other side
of the comparison. movie_subtitle::track_voice_cues returns (u32, f32) and I
have been reading that f32 as SECONDS on the strength of the format notes
describing mm:ss.cc cue text. If it is centiseconds, a frame index or a
per-page offset, every "audio missing" verdict inherits the error. Recorded
as the next thing to check, and to be checked BEFORE any more audio work.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMRJjbxLqZtsb5Vb7KunPE
cfe9bd863f