[Openchrome-devel] Hardware video decoding performance

Bart Hartgers bart.hartgers
Wed Jun 17 06:42:10 PDT 2009


Since a lot more documentation for the VIA chips was released recently, I
decided it was a good moment to see if I
could get MPEG2/MPEG4 acceleration working for the CX700 chip on my EPIA
EX15000. I made some progress in studying and
disassembling the original VIA XFree86 drivers on
(CX700XF40064-kernel-src_20060222d) viaarena.com. I've done linux driver by
reverse engineering
before, although for less complex hardware. Then again, there actually are
quite some pieces in the provided source, the remaining binary-only part
is relatively small.

At the moment I have good hope that I could get it to work, if I spend
enough (probably considerable) time on it. However, this brings
me to the point of this mail: how relevant is this decoding-ability? This
depends on the decoding performance of the chips,
relative to the decoding performance of the CPU itself. And I cannot find
hard information about the first .

With proper hardware decoding performance, can I expect a (say) 1GHz C7 to
handle MPEG2-HD on 1080i or 720P?
And what about MPEG4? All info I could find just says 'MPEG4' is
accelerated, but what bitrates are feasible, and is this MPEG4-ASP, or
MPEG4-AVC (aka H.264)?
I am guessing decoding blueray would be out of the question, but some hard
data would be appreciated.

I understand that VIA cannot give us proper documentation for the video
decoders, but I suppose they could tell more about the possible performance.

Or is there already information available on this, that google doesn't want
me to have? ;-)

Thanks in advance for any thoughts or information on this.

Bart Hartgers - New e-mail: bart.hartgers at gmail.com
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