hi
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. pat