[FFmpeg-user] Help needed to work around incorrect DTS when capturing H264 from a Logitech C920

Peter Rabbitson rabbit+list at rabbit.us
Tue Dec 16 10:44:52 CET 2014


On 12/16/2014 10:33 AM, Carl Eugen Hoyos wrote:
> Peter Rabbitson <rabbit+list <at> rabbit.us> writes:
>
>> a playback of the stream via `ffplay -i stdin.h264`
>> seems to run faster.
>
> You can now use the input option "-r 30" to remux
> this stream with "correct" timestamps.
> (I am not sure if they will really be correct but
> playback works fine here.)
>
> The output will never be perfect because you have
> reception errors in your input stream. Consider
> using mpegts which allows such errors, I suspect
> all other file types are invalid whenever such
> errors occur.

Which brings me back to the question about ffplay - how does it manage 
to compensate for (apparently) perfect timing as long as I feed it STDIN 
in special chunks at special times?

Basically - is there a way to take the h264 frames as they come down 
from the camera, and force-set the PTS based on a wallclock or something?

Basically "the output will never be perfect" is not something I am 
willing to settle for. I either want to find out what is causing it, or 
how to work around in a perceptually-satisfactory manner (which the 
scheduler | ffplay example implies *is* possible)



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