On Thu, Sep 16, 2010 at 5:34 PM, Tomas Härdin <[email protected]>wrote:
> Please don't top post on this list. It makes it harder for people to > read it. > > On Thu, 2010-09-16 at 17:02 +0400, Kulti wrote: > > Hm... Thanks, I'm use flv-container, but how to set VFR? It's mean, that > I > > need to modify AVCodecContext.time_base before encoding every frames? > > > > On Thu, Sep 16, 2010 at 4:43 PM, Tomas Härdin <[email protected] > >wrote: > > > > > On Thu, 2010-09-16 at 13:36 +0400, Kulti wrote: > > > > Hi, all. > > > > > > > > I have a webcam and need to transcode mjpeg to any formats, but > sometime > > > > webcam lagged and fps fall down. Can ffmpeg atuo fill dropped frames > to > > > > constantly fps? > > > > > > Why do you want constant fps? Just use a container that handles VFR > > > (avi, flv, mov etc.). > > > > > > Anyway, assuming the frames are timestamped correctly ffmpeg should > > > behave correctly. If not, try forcing constant framerate with -r. > > > > > > /Tomas > > > > > FLV has a fixed time base of 1 kHz, so it's always VFR. In other cases, > like AVI, you can set time_base to be less than or equal to the inverse > of the maximum fps. > > In other words, if you know your camera can't deliver more than 50 fps > you can set time_base to 1/50, 1/123, 1/10000 or whatever. In the > specific case of AVI you shouldn't set it too low though, since it pads > with empty packets for the "missing" time stamps (IIRC something like > 39*16 = 624 B overhead if you mux 25 fps with a time base of 1 kHz). FLV > does not have this problem though. > > Hope that helps :) > > /Tomas > > _______________________________________________ > libav-user mailing list > [email protected] > https://lists.mplayerhq.hu/mailman/listinfo/libav-user > > Sorry for top-post... and thanks for your help. So, I set time_base to fixed value 1/25 (that I get from AVCodecContext for mjpeg-decoder). Then I added timer and frame-counter before av_write_frame(). I see, that fps is 19-21. But I need live-streaming. So, I hardcoded time_base to 1/20, and all works fine before webcam is not lag, but after fall down fps to 15 transcoding process broken. Yes, I understand, that must be working for transcoding into file, but I need real-time transoding for live streaming. I can't see any way instead inserting frames, when some drops... _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
