1. I use google to search the mailing list 2. if by specific frames you mean you want to extract from frame 300 to 350, the easiest way is to simply parse the video from the beginning, until you reach the desired frames.
there is "av_seek_frame" in the library and it's quite fast but it's an approximate jump (at least for the mpeg ts files I work with), and you would be able to jump "somewhere around" frame 300, but not knowing exactly were you are. To counter this, I pre-parse the video to see where different jumps arrive at, so I can jump later at any exact frame: step 1: parse the video frame-by-frame and remember for each frame it's pts/dts in a vector step 2: try to jump to different frames with av_seek_frame and compare the pts/dts of the found frame with the table from step one to see where you actually arrived at. you'll get a vector like this: jump to frame 100 -> arrived at frame 94 jump to frame 200 -> arrived at frame 196 etc. etc. 3. I guess you could insert your own decoder into the library to extract the info. Regards. On Thu, Oct 22, 2009 at 12:10 PM, Stefano Sabatini < [email protected]> wrote: > On date Thursday 2009-10-22 16:43:32 +0800, S R encoded: > > 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. > > Mailman archive interface is rather dumb, try this instead: > http://dir.gmane.org/gmane.comp.video.ffmpeg.libav.user > > > 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. > > Maybe the ffprobe code. > > > 3. Is there an example code that explains how to extract the motion > vectors? > > I'm not sure libavcodec exports that information, for sure you can ask > libavcodec to show them in the decoded image, check for example the > -vismv option of ffplay. > > > Appreciate your help with the above. Thank you! > > Regards. > _______________________________________________ > libav-user mailing list > [email protected] > https://lists.mplayerhq.hu/mailman/listinfo/libav-user > -- Bogdan COANDA AIESEC Iasi AIESEC in Romania Mobile: +40-724 013 068 E-mail: [email protected] Website: www.aieseciasi.ro _____________________________________________________________________________ AIESEC - The international platform for young people to discover and develop their potential _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
