[GEM-dev] Video Codecs Seek performance... *sigh*

IOhannes m zmoelnig zmoelnig at iem.at
Thu Nov 3 22:25:48 CET 2005

B. Bogart wrote:
> Hi all,
> Now that the smoke has cleared a bit from my installation in Ottawa, I'd
> like to ask about some performance issues with file seeking.
> I'm now using mpeg2 (dvd quality or so) encoded videos with single frame
> GOPs, and seeking them using the table of contents generated by mpeg3toc.
> The problem is that two 640x480 videos seeking randomly use up 80% of my
> new AMD64 3200+. This seems to be a bit of a hog... I also endcoded a test
> file as "photo-jpeg" in a quicktime container. I could also seek that
> file, but the CPU usage was about the same - 10%.

i have had very similar problems when playing back 2 PAL-videos
(uncompressed) with a machine similar to yours (although the 2 video
files were on spread on two SATA-raids (raid0, 2 disks)

even though the disc-access should not be a problem, it seems like
pd/Gem spent most of the time waiting for the 2 raids.

thus i have changed [pix_film] (and [pix_movie]) to access the
disc-arrays in a threaded way.
this sped up performance significantly.

the changes are in the CVS. you can turn on/off threading with [thread
0/1( to the [pix_film]/[pix_movie]


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