[FFmpeg-user] Using ffplay to play a video during creation

Marton Balint cus at passwd.hu
Wed May 14 02:31:14 CEST 2014

On Tue, 13 May 2014, Zack Thevenot wrote:

> I am using ffplay to essentially stream a video from another device.  I 
> have the device continually creating a H264 video file and transmitting 
> it to a PC in 2KB packets, and ffplay is playing it on the fly, even as 
> the file is being appended to.  What I would like to do is make this 
> process cleaner on ffplay.  Every so often, from what I can tell, ffplay 
> tries to play an incomplete frame and the video grays out or blurs.  Is 
> there a way I can tell ffplay to pause at the last good frame? Or to 
> play/continue playing only when there are good frames yet to play? Or 
> maybe something else is going on?

Some demuxers just flush their incomplete packets if they reach the end 
of file, so the codecs will get corrupted packets. I don't think this can 
be easily fixed, so a better approach instead of playing a file which is 
being appended to is to do some kind of streaming, and play the stream.

You may try to find a "tail -f" like program for binary files, and pipe 
the output to the standard input of ffplay and play the standard input, 
and see how it works.


> I would just like to know if cleaning up my stream is possible through 
> ffplay rather than my input.  If I do have to process my input 
> further, I'm not very familiar with H264 format and could use some 
> resources.

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