[MPlayer-users] high-res videos too slow, where's the bottleneck?

Marcus Blomenkamp MBlomenkamp at t-online.de
Wed Oct 31 16:38:59 CET 2001

I'm experiencing an annoying problem which doesn't let me enjoy high quality 
divx movies: Streams with higher resolutions (eg 720x756) are played back too 
slow - it's easily noticeable and mplayer claims it too... The story:

I've got the same movie in two different sizes/formats so I can compare some 
things: variant A has a resolution of 720x576 with black borders encoded 
above and below and variant B contains just the 'active area' with a 
resolution of 704x416. The bitrate of the low-res movie is even higher 
(A:100kB/s vs B:140kB/s). Now to the result: The low-res movie can be played 
flawlessly with lots of cpu-time left over (around 40%), however the big 
stream hogs the cpu completely and playback is very choppy. I doubt that the 
cpu is too slow to decode the movie itself because if I discard the 
video-output ('-vo null') the cpu usage is nearly identical (27% vs 28%). 

Somehow the problem must reside in the amount of transferred image pixels. Is 
colorspace conversion falsely NOT done by hardware? Or is the RAM too slow to 
cope with the fullscreen images?

Abit BH6 + Celeron 466
384M RAM
ATI Rage 128 AGP 32M
Mandrake 8.1
XFree 4.1 (16Bit, r128 driver not gatos) 
gcc 3.01
mplayer 0.5 (odivx, playback over sdl/xv)

cu Marcus

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