[FFmpeg-user] why ffplay cannot decode a sequence that can be decoded by ffmpeg

Moritz Barsnick barsnick at gmx.net
Sun Jun 10 03:20:03 EEST 2018

On Sat, Jun 09, 2018 at 21:44:28 +0200, Carl Eugen Hoyos wrote:
> ffmpeg (the application) supports several audio output
> devices like alsa, pulse and oss. They may be what
> you need.

But Mohammed's input video didn't even have an audio stream?

I'm still convinced it's either an ffplay bug, or it's intended.
"The file contains only audio, and '-an' is given, so refuse to play."
"The file contains only video, and '-vn'/'-nodisp' is given, so refuse to play."
"The file contains audio and video, and at least one of them isn't disabled, so go ahead with decoding."

I'm not sure the video decoder is used with '-vn'/'-nodisp', so perhaps
running ffplay like this doesn't fulfill Mohammed's cause.
"ffmpeg -i ... -f null -" may be more effective.

$ ffmpeg -f lavfi -i testsrc -t 10 test.vid.mp4
$ ffmpeg -f lavfi -i sine -t 10 test.aud.mp4
$ ffmpeg -f lavfi -i testsrc -f lavfi -i sine -t 10 test.vid+aud.mp4
$ ffplay -nodisp test.vid+aud.mp4
$ ffplay -nodisp test.aud.mp4
$ ffplay -nodisp test.vid.mp4

The last one fails with said error. So does
$ ffplay -an test.aud.mp4 


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