rsg wrote > > Hi, > > I am also facing a similar issue. > When I set the bit rate using > > out_vcodec->bit_rate = 200000; > > the quality of the video goes very bad. But when I set qmin and qmax, the > bitrate setting is ignored. > Only when i set a high value (approx 100MB) for the bit rate, the quality > of the video improves. > >
Yes that is the same thing I'm seeing. If qmin/qmax are left at -1 (default), then no matter what bitrate is specified, quality is very bad (and the bitrate is not honored). The upper half/third of the image looks good and the lower area looks really bad. The dividing line also changes every couple of frames. For example see this screenshot: https://dl.dropbox.com/u/7730988/encode_prob.png The only way I found to avoid this problem is to set qmin/qmax but then the resulting video is not ABR/CBR. Here is the same frame compressed with all settings the same as before, except set qmin=1, qmax=31: https://dl.dropbox.com/u/7730988/qminqmax.png Obviously ffmpeg can do it right so I'm sure we are doing something wrong, but I haven't yet found the difference in how ffmpeg is setting the libx264 options such as bitrate differently than what we are doing here. Hope someone else has an idea... Thanks. -- View this message in context: http://libav-users.943685.n4.nabble.com/Setting-libx264-bitrate-via-API-tp4655453p4655479.html Sent from the libav-users mailing list archive at Nabble.com. _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
