[FFmpeg-user] Can't synchronize two webcam streams side by side using ffmpeg

[bob Darkblue]

>> [0:v] setpts=PTS-STARTPTS,
>> [1:v] setpts=PTS-STARTPTS,

>Isn't this making sure that the two streams are not synchronised?
I copy pasted it from
https://trac.ffmpeg.org/wiki/Create%20a%20mosaic%20out%20of%20several%20input%20videos

I don't understand it quite well but it should take care of the little
difference in start time between :
Input #0, video4linux2,v4l2, from '/dev/video1':
  Duration: N/A, start:* 858.256014*, bitrate: N/A
 ...
Input #1, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start:* 858.878636*, bitrate: N/A

I've also tried to remove the option and also tried with setpts=PTS but
there is still a ~1s synchronization issue.


>>> ffmpeg version 3.2 Copyright (c) 2000-2016 the FFmpeg developers

>Please remember to test current FFmpeg git head before asking
>for support here.

I'm currently compiling it. Will retest on the git version when the
compilation is done.




On Sat, Dec 3, 2016 at 3:46 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 2016-12-03 15:26 GMT+01:00 bob Darkblue <darkbluewonderfulworld at gmail.com
> >:
>
> > It works but there is a delay of ~1 second between the two screens.
>
> > ffmpeg -f v4l2  -framerate 15 -video_size 1280x720 -input_format mjpeg -i
> > /dev/video1 -f v4l2 -framerate 15  -input_format mjpeg -video_size
> 1280x720
> > -i /dev/video0 -filter_complex "
> > nullsrc=size=2560x720 [background];
>
> > [0:v] setpts=PTS-STARTPTS,
> > [1:v] setpts=PTS-STARTPTS,
>
> Isn't this making sure that the two streams are not synchronised?
>
> > ffmpeg version 3.2 Copyright (c) 2000-2016 the FFmpeg developers
>
> Please remember to test current FFmpeg git head before asking
> for support here.
>
> Carl Eugen
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