On Thu, Oct 22, 2009 at 4:43 AM, S R <[email protected]> wrote: > Hi > > I am learning to use ffmpeg for my research work. > > I have three questions: > > 1. Is there a way to search the libav-user list by topic or subject? I > cannot find one. > 2. I am trying to extract some specific frames from a video file. Is there > any example code that tells how to do it. I already know how to get frames > from a video from the beginning, as I got an example code from the ffmpeg > tutorial. > 3. Is there an example code that explains how to extract the motion vectors?
Look at ff_print_debug_info in mpegvideo.c, that's where the MV visualization code is handled for mpeg-type video. The MVs are in avframe's motion_val, but unfortunately a lot of the bookkeeping values you need to properly extract those aren't exposed by lavc's public API. Some of these values, you can safely guess for use in your app (eg, afaik the # of macroblocks is usually video_width/16*video_height/16), but I don't know if a completely non-hackish extraction is possible at all. Good luck. > > Appreciate your help with the above. Thank you! > > regards > snd > _______________________________________________ > libav-user mailing list > [email protected] > https://lists.mplayerhq.hu/mailman/listinfo/libav-user > _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
