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

[Carl Eugen Hoyos]

2018-06-10 2:20 GMT+02:00, Moritz Barsnick <barsnick at gmx.net>:
> 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.

Really?

> "The file contains only audio, and '-an' is given, so refuse to play."

Yes.

> "The file contains only video, and '-vn'/'-nodisp' is given, so refuse to
> play."

Yes.

> "The file contains audio and video, and at least one of them isn't disabled,
> so go ahead with decoding."

Yes.

> I'm not sure the video decoder is used with '-vn'/'-nodisp',

It should not be used afaict.

> so perhaps running ffplay like this doesn't fulfill Mohammed's cause.
> "ffmpeg -i ... -f null -" may be more effective.

It is certainly a good idea if he just needs a performance test.

> $ 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

These work as expected afaict.

> $ ffplay -nodisp test.vid.mp4

This can only fail afaict (and it does).

What do I misunderstand?

Carl Eugen