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

B. Bogart ben at ekran.org
Thu Nov 3 19:00:04 CET 2005

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'm reading the files off a dual disk SATA raid0, so the disk access
should not be the problem. (I can play 3 DV videos off the same array
using mplayer w/out lost frames.)

So the question is:

#1 What is the best video codec for random seeking performance?

#2 How can I profile pd/gem/diskIO/decoding to find out what is causing
the largest bottleneck? Suggest tools?

My previous installation used 256x256 photo-jpeg MOVs playing
simultaneously on a duron 900 and gem 0.87. These videos were just played
and not seeked.

Thanks all! I'd really like to be able to get better performance out of
this patch.


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