On 08.09.2013 18:32, Alex Cohn wrote:
On Sep 8, 2013 6:17 PM, "Sandro Mani" <[email protected]
<mailto:[email protected]>> 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: [1] [2].
>
> Thanks for any inputs.
>
> Sandro
>
>
> [1] http://smani.fedorapeople.org/VideoCapture.hpp
> [2] 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.
BR
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.)
Sandro
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