#11138: FFmpeg audio dither creates unwanted DC offset
-------------------------------------+-------------------------------------
Reporter: mstgrv | Type: defect
Status: new | Priority: normal
Component: | Version: 7.0
undetermined |
Keywords: audio | Blocked By:
dithering |
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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I ran a test of FFmpeg's audio dithering and I noticed that it creates a
DC offset in the resulting audio file, which shouldn't be there. Doing the
same dithering process with other tools produces no DC offset in the
resulting audio.
Here's what I did:
1. Create a silent WAV file (44.1khz, 32-bit floating point) using iZotope
RX.
2. Convert that file to 16-bit with triangular dither, using iZotope RX
3. Convert the same file to 16-bit with triangular dither, using FFmpeg.
The command I used was:
{{{
ffmpeg -i input.wav -c:a pcm_s16le -dither_method triangular output.wav
}}}
Because the file in step 1 is completely silent, the files created in
steps 2 & 3 contain just the dither by itself.
FFmpeg's conversion results in a file with DC offset, but iZotope RX's
conversion has none. The expected result is no DC offset.
I have attached all the WAV files, plus screenshots of the analysis of
each file (using iZotope RX) which shows the DC offset result.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11138>
FFmpeg <https://ffmpeg.org>
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