[PD] Gem CVS + pd-0.41-0test9 + Ubuntu Gutsy : Not reading videofiles

patrick puredata at 11h11.com
Sun Dec 9 01:16:42 CET 2007

> i am not sure, if i understand why you want to get xvid working with
> gem. if you are interested in lowest possible cpu consumption, i
> wouldn't expect xvid to give the best results, since it is optimized to
> give very high compression and not to consume as little cpu as possible.
after testing many codec on linux, XVID is the best codec for filesize 
and cpu. both. playing a dv, jpeg quicktime or mjpeg avi are +- 35% of 
my cpu (640x480 / 30 fps). XVID will take only 7% of my cpu and the 
filesize is reduced by half. by forcing keyframe every frame i can (in 
theory) use it like jpeg, mjpep (skip, scratch etc...).
> probably some people with better knowledge (devs?) can shed light on
> this, but i suspect, that the decoding might not be the major reason,
> why gem uses so high cpu load, when displaying a video, but probably the
> transport of the data. aaik, mplayer is highly optimized in that
> respect, so if using a fast output as -vo xv, almost all cpu cycles are
> used for decompression, neither for displaying nor for transport. -vo gl
> eats 60% (50% @ 600MHz) more cpu than -vo xv (31% @ 600MHz). so
> displaying through opengl (what gem does as well) seems to add some
> overhead. 

right! decoding a quicktime jpeg in gem or in mplayer -vo gl is the same 
cpu consumption.  but there's a problem with xvid decoding mechanism.

i filled a bug report in sourceforge.

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