Hi, On Mon, Nov 19, 2018 at 16:14:03 +0800, 林至善 wrote:
> I need a down-sampled(=8kHz) version of my input.wav file (=16kHz). > > According to > https://trac.ffmpeg.org/wiki/FFmpeg%20and%20the%20SoX%20Resampler, > I use the command below > > ffmpeg -i In16k.wav -af aresample=resampler=soxr -ar 8000 Out8k.wav > > It works well, but I found that every time I run the command above, > it returns the "Out8k.wav" with a slightly different(in PCM value). Interesting. But first of all, I believe your command line is wrong. "-ar" uses ffmpeg's native resampler, I believe. Using the filter, you need to pass the rate to the filter itself: ffmpeg -i In16k.wav -af aresample=resampler=soxr:sample_rate=8000 Out8k.wav You could also just use any other resampler, e.g. by omitting "-af aresample=resampler=soxr" fully. I don't have soxr support, so I can't reproduce your issue. It should be deterministic. Perhaps some metadata thing. > *If I want a resampler which always returns the same result, how can I do? Can you try whether the command line option "-bitexact" changes anything? Moritz _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".