[Open-graphics] CPU on graphics card]

[James Richard Tyrer]

Nicholas S-A wrote:
>> To be practical, both cost and power wise, this solution would have
>>  to be based on an embedded chip.
>> 
>> AMD Geode processors can be used to make a graphics card. They 
>> support MMX and 3D-NOW.  AMD states that they fully support Linux 
>> on these.
>> 
>> http://www.amd.com/us-en/ConnectivitySolutions/ProductInformation/0,,50_2330_9863,00.html
>> 
>> 
>> 
>> 
>> The GX or LX would be a single chip solution. It would be 
>> inexpensive, but I don't know how fast it would be.  They have the 
>> advantage of having hardware VGA.  The LX is a bit faster than the 
>> GX.
> 
> You do *not* want to use the Geode, LX or GX, for video processing 
> except in a very specialized app. There is actually a discussion on 
> devel at laptop.org right now talking about using OpenGL (read Mesa) on 
> the LX they use for the XO. It has nowhere near the needed processing
>  power to run that - I assume any other OpenGL implementations would 
> be as limited, and would not compete with even 7200-era cards.

They both have 3D-Now and MMX, so this would be what the original poster
suggested.  If the fastest (> 1 GHz) LX isn't fast enough for a medium 
price video card, then the idea isn't viable.  Using a regular CPU 
running at over 1 GHz simply isn't practical either price or power wise.

> A possibility could be the Xscale and intel 2700: 

> http://en.wikipedia.org/wiki/Intel_2700G which supports OpenGL ES.

Isn't an X-Scale just a fast ARM?  But, yes, using one of the chips --
such as the 81341 or 81342 (dual core) might work for part of the video 
board.  They have the system bus interface DDR2 & DMA controllers.  The 
GPU would have to be connected via PCI-X which has points both positive 
and negative.

I will read up on the 2700.

> Also, this information might be useful to us: The 2700G performs 
> Inverse Zig-Zag, Inverse Discrete Cosine Transform, and Motion 
> Compensation to speed up MPEG-1, MPEG-2, MPEG-4 and WMV video 
> decoding. The accelerator can decode MPEG-1, 2 and WMV at 720x480 
> (DVD Resolution) and MPEG-4 at 640x480, both at over 30 frames per 
> second.
> 
> These all run at 75 Mhz

75 MHz seems a bit slow. :-D

> - It is likely that we will be able to decode slightly better than
> this if we implement those features. Given the R&D intel must have
> put into this chip, that is probably where 99% of the CPU power goes.
> 
I think that chips intended to make a set-top box might be usable for a 
medium price video card which could also decode h.264 HiP 1080p/30 -- it 
would also include a sound card.

-- 
JRT