The actual HiFi/Monochrome bug isn't silence padding — it's a TRUNCATED file:
the container claims the full length (e.g. 3:08) but only ~30s of audio
decodes. silencedetect finds nothing (there's no silent audio, just missing
audio) and ffmpeg's time= even reports 0 with no error, so the duration and
quality guards all pass.
Detect it by decoding and comparing the real audio length (astats sample
count / sample rate) against the container duration: reject when the real
audio covers < 85% of the claimed length. detect_broken_audio() runs this
truncation check first, then the silence-ratio check. Wire it into the guard
that runs at the integrity/length verification point.
Verified on the real file: 'only ~30s actually decodes of a 188s file (16%)';
a normal 180s file is not flagged.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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