[FFmpeg-user] Dithering in 'aresample' has no effect

Michael Niedermayer michael at niedermayer.cc
Fri Dec 7 03:00:51 EET 2018

On Tue, Dec 04, 2018 at 11:56:18AM +0800, 林至善 wrote:
> Hi all,
> I am trying to compare the wav file with/without dithering, but it seems
> that my command doesn't work. Here's my command line and console output:
> [1] *ffmpeg -i Fsweep96.wav -af
> aresample=8000:dither_scale=0:dither_method=0 Fsweep8_NoDither.wav* (I
> would assume this would generate a file *without *dither,
> Fsweep8_NoDither.wav)
> [image: 1.JPG]
> [2]* ffmpeg -i Fsweep96.wav -af
> aresample=8000:dither_scale=1:dither_method=rectangular Fsweep8_Dither.wav *(I
> would assume this would generate a file *with *dither, Fsweep8_Dither.wav)
> [image: 2.JPG]
> But the output file Fsweep8_NoDither.wav/Fsweep8_Dither.wav are totally the
> same, both the wav header and the PCM value(it should be
> increased/decreased by a small value like +-1 in Fsweep8_Dither.wav).
> The question is :
> *It seems that my command doesn't work. Is that correct? If I want to
> enable/disable dithering, what command should I use?

try choosing a more precisse internal sample format, for example:
"-internal_sample_fmt fltp" 


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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