[Libav-user] help with raw fifo as movie src & overlay

Andrey Utkin andrey.krieger.utkin at gmail.com
Wed Feb 15 10:00:15 CET 2012

2012/2/15  <gstream at ccc2.com>:

> assume its because of the RTSP codec and timestamps not being the most
> accurate.
> I am keen for advice on constructing the filter you mentioned, are there
> any tutorials?

I think more probably timestamps are ok, but inter-frame interval
(FPS) may be not very accurate. And maybe overlay filter just gets one
frame from one source, and one from another, and puts together, thus
if one camera may "forget" to send particular frame sometimes, the
second source will "be late" on visualization. If we had a filter that
forces constant frame rate, this could be solved. (Just speculations

> Also a bit of a NooB Q. but is there a way to update/change parameters
> once the cmd has been started? In particular if we can get this delay
> fixed, I am assuming some form of drift over a 60+ period and we would
> need to dynamically adjust this over time.

For cmdline util, it's impossible. For API that's re-initializing all
filtering stuff. You can do it, but it's a lot of code. You must read
your streams and push to filters manually, not by 'movie' filter.

Andrey Utkin

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