[FFmpeg-trac] #7949(undetermined:new): libopus ocl=downmix fails
FFmpeg
trac at avcodec.org
Mon Jun 10 07:44:32 EEST 2019
#7949: libopus ocl=downmix fails
-------------------------------------+-------------------------------------
Reporter: omniplex | Type:
| enhancement
Status: new | Priority: normal
Component: | Version: 4.1
undetermined |
Keywords: OPUS | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug: unlike libtheora the libopus default
[http://ffmpeg.org/ffmpeg-codecs.html#libopus -mapping_family -1] does not
permit [https://ffmpeg.org/ffmpeg-utils.html#channel-layout-syntax
ocl=downmix]. How to reproduce:
{{{
% ffmpeg -i input -vn -filter:a
aresample=48000:resampler=soxr:precision=28:ocl=downmix:cheby=1:matrix_encoding=dolby:tsf=s32p
-c:a libopus -b:a 25KiB output
ffmpeg version 4.1.3 built with gcc 8.3.1 (GCC) 20190414
}}}
The same command with [http://ffmpeg.org/ffmpeg-codecs.html#libopus
-mapping_family 255] works.
Maybe it is only me, but I expected [https://ffmpeg.org/ffmpeg-utils.html
#channel-layout-syntax ocl=downmix] to work for ordinary MP3 stereo input
while upgrading a script from VP8/libtheora to VP9/libopus. It's no bug,
but had a [https://en.wikipedia.org/wiki/Principle_of_least_astonishment
high astonishment factor].
--
Ticket URL: <https://trac.ffmpeg.org/ticket/7949>
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