[MPlayer-users] Slow playback of x264 video in mkv

[Fredrik Eriksson]

So, I created a x264 video with mplayer using the following command:

mencoder-cvs -dvd-device koikoi7.dvd2.real.iso dvd://1 -chapter 1-1 
-ofps 24000/1001 -vf pullup=::::1:,softskip,hqdn3d=4:2:2 -nosound -ovc 
x264 -of rawvideo -x264encopts 
subq=6:frameref=7:me=3:4x4mv:bframes=4:b_adapt:b_pyramid:qcomp=0.7:keyint=300:8x8dct:pass=3:bitrate=1400 
-o koikoi7.intro.x264.h264

then I muxed the video to a mp4 container:

MP4Box -fps 23.976 -add koikoi7.intro.x264.h264 koikoi7.intro.x264.mp4

the video plays just fine with mplayer-cvs, with about 20% CPU usage.
But then I mux it to a mkv container:

mkvmerge -o koikoi7.intro.x264.mkv --timecodes 1:timecode.tmc --vtracks 
1 koikoi7.intro.x264.mp4 -a 0 koikoi7.intro.audio.ogg

now the video playback is too slow and jaggy, the audio gets quickly out 
of sync, although the CPU usage is about the same as with the mp4 file. 
I tried the file on my laptop, and the special build of ffmpeg included 
in CCCP (http://cccp.kickassanime.org/) could play the file just fine, 
so it's most likely not a problem with the file.

does anyone know what the problem might be?