[FFmpeg-user] audio video sync and drift

[John Smith]

Thanks for your response.

So is there anything I can do or change, to get this to work? Is there no
way to record audio and video from different sources, and just use "wall
time" or "time elapsed since executing ffmpeg" to sync up the audio /
video?

There may be jitter in /dev/video1... but when I view /dev/video1 while
streaming, the /dev/video1 does not appear to delayed by any amount. Yet in
the stream, the video plays later in time than the audio does. So there
appears to be some disconnect there between the time the frame appears in
/dev/video1 (perfectly in time) vs when ffmpeg displays (poor choice of
words) the frame in the output stream where it comes later in time.

So explaining that again in my simple laymans terms: lets say frame
#112,500 is sent to /dev/video1 at the 75 minute mark. When viewing
/dev/video1 through a secondary process, that frame does appear at that
time. But in the ffmpeg stream, frame #112,500 might end up playing at
75:01:200 instead of 75:00:000


John



On Wed, May 2, 2018 at 4:26 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 2018-05-02 22:19 GMT+02:00, John Smith <localdevjs at gmail.com>:
>
> > Now at this point I want to stream video, and record video
> > from my mixer. ffmpeg reads the video from /dev/video1,
> > and the audio from tcp://localhost:55555.
>
> This cannot work as these sources do not have a common
> timeline: Since the v4l2 device most likely shows some
> jitter, you cannot keep A/V sync.
>
> Carl Eugen
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