[FFmpeg-user] ffplay does not seems to downmix 5.1ch audio to Stereo with "-ac 2"

Kimio Miyamura xanadu at apost.plala.or.jp
Wed Nov 19 14:38:41 CET 2014

2014/11/19 21:46, Carl Eugen Hoyos <cehoyos <at> ag.or.at> wrote: 

> Kimio Miyamura <xanadu <at> apost.plala.or.jp> writes:
>> If I use "-ac 2" with ffplay like the following, 
>> seems to right side channel sound have lost.
> Do you see anything suspicious if you press "w" while 
> playing to see a visualization?

Yes, the video would be lost.  pressing "w" one time, the video goes to black with white and purple oblique line. pressing "w" again, the video goes to complete black, pressing "w" one more time, the video comes back.  
Am I correctly describe the video state?

>> $ ffplay -i test.mp4 -ac 2
> Please test the following:
> $ ffplay -i test.mp4 -af aresample=ocl=stereo

Nice!!  With above command, I can playback all audio correctly.  I'm happy aren't I?
So if I can playback audio with above ffplay command, don't I need to downmix audio at the timing of encoding?

// Miya 

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