I've noticed lately that video I create with webm's ivfenc, using the "--auto-alt-ref=1" setting, stutters during pans (especially after a scene change) when played in mplayer. When I view the clips in vlc or using gstreamer, the video looks smooth. When I make video with auto-alt-ref disabled, it looks normal in all players.
Here's an example problem clip (15 second vp8 stream as an ivf file): https://docs.google.com/a/duanerobertson.com/leaf?id=0B8fG4DFq4jlRNGFhNDBhZTAtMTEzYi00YjQyLWJiM2UtMGZhZjU1YjIxYmYw&sort=name&layout=list&num=50 I've been going through the libavcodec/vp8* code, and struggling to understand it, but I have noticed one interesting thing already--the problem seems to be (directly or indirectly) associated with failing to set the previous frame buffer to the current frame data. When I force an update every time, so: //if (s->update_last) // move cur->prev s->framep[VP56_FRAME_PREVIOUS] = s->framep[VP56_FRAME_CURRENT]; video created with "--auto-alt-ref=0" will play with no apparent problems. However, the clip created with auto-alt-ref enabled shows video breakup at the same points I would see skipping when using mplayer compiled normally (latest svn). I don't think that my computer's configuration is responsible, since I can get the same stuttering on my laptop or desktop. Obviously sound isn't a factor (since there is none). I've also transcoded the problem samples with ffmpeg and mplayer plays the result smoothly. I used ivfdec to create raw video which mplayer played smoothly. Can anyone give me any suggestions about what might be happening or where to look next? _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
