[Libav-user] libavformat, RTSP: periodically read last available frame of live stream
manisandro at gmail.com
Sun Sep 8 19:15:15 CEST 2013
On 08.09.2013 18:32, Alex Cohn wrote:
> On Sep 8, 2013 6:17 PM, "Sandro Mani" <manisandro at gmail.com
> <mailto:manisandro at gmail.com>> wrote:
> > Hello,
> > I would like to periodically (say every second) grab the latest
> frame from a rtsp live stream of a webcam. I am able to successfully
> open the stream and read and decode frames, however if I read one
> frame every second, I am still reading subsequent frames (as opposed
> to frames which are i.e. one second apart). I guess I need to seek to
> the last available frame before reading the next frame. Can anyone
> point out how this can be done?
> > For reference, my code is here:  .
> > Thanks for any inputs.
> > Sandro
> >  http://smani.fedorapeople.org/VideoCapture.hpp
> >  http://smani.fedorapeople.org/VideoCapture.cpp
> If your webcam has GOP of 1 sec, e.g. GOP length = 30 and FPS = 30,
> you can skip to next second; otherwize, the correct strategy would be
> to decode all frames, but throw away all frames that you don't need.
> Alex Cohn
Thanks for the reply. With skip do you mean by calling av_seek_frame
with an appropriately computed timestamp? (Sorry if I may be asking the
obvious, I'm rather a novice in this area.)
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