[FFmpeg-user] Audio resampler (SoX) returns different result

Carl Eugen Hoyos ceffmpeg at gmail.com
Mon Nov 19 16:27:55 EET 2018

2018-11-19 9:14 GMT+01:00, 林至善 <g104972 at gmail.com>:
> Hi all,
> 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

Please always provide the command line you test together with
the complete, uncut console output when asking for support here.

> 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).
> The question is :
>   *Is the difference I found a normal phenomenon?

>   *If I want a resampler which always returns the same result, how can I do?

FFmpeg's default resampler is deterministic.

Carl Eugen

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