Replace sox with ffmpeg for audio conversion and filtering#2
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Use ffmpeg for converting audio to raw PCM and for bandpass filtering. The bandpass filter uses ffmpeg's sinc FIR kernel generator with afir convolution, which closely matches sox's sinc filter quality (steep rolloff, flat passband, linear phase). Updates README and CI workflow to reference ffmpeg instead of sox.
farski
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Apr 2, 2026
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With the caveat that I didn't investigate those FFmpeg filters very much, and I have no experience with FIR, this all seems reasonable
The irnorm option was added in ffmpeg 7.x. Dropping it makes the bandpass filter work with Ubuntu's ffmpeg 6.1.1 package without affecting detection results.
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Use ffmpeg for converting audio to raw PCM and for bandpass filtering.
The filter options between the 2 are not quite the same - the
bandpassfilter in ffmpeg is not equivalent.This implementation uses ffmpeg's sinc FIR kernel generator with afir convolution, which closely matches sox's sinc filter quality (steep rolloff, flat passband, linear phase).
Makes the change to the code, and updates README and CI workflow to reference ffmpeg instead of sox.