[Libav-user] programmatic frame rate control?

Ulrich Teichert ulrich.teichert at axiontech.de
Fri Dec 23 09:33:53 EET 2016


> I’m studying this right now:
> http://stackoverflow.com/search?q=libav+pts+dts
> The top result looks promising. Getting timecodes right look like a challenge...

This highly depends on your video source. For instance, some cameras are setting proper
presentation time stamps in their streams, most don't. In encoded files the timestamps
are somewhat better, I believe.

My solution was to have an external clock source, as Eric Lee has suggested already:

> > On Dec 22, 2016, at 10:13 AM, Eric Lee <erclee2 at gmail.com> wrote:
> >
> > You could try using an external timer and parameters from the AVFrame
> and AVCodecContext such as pts, duration, and framerate to control the
> presentation of decoded frames.

.. but when you don't have presentation time stamps in you frames, or you can't rely
on them, you can try to compute how "long" a frame you have decoded should be
shown on the screen, which normally leads to non-perfect video, as this may totally
differ from the proper presentation time for the frame.


Ulrich Teichert

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