[mythtv] 3 Channels Simultaneously, just expand with a DSP

mbox mbox at cloppy.net
Thu Feb 6 23:27:54 EST 2003

There is the extension I dreamed off:

Here some performance and design considerations:

That was designed then annouced last august, a fast FGPA fitting in a free
RAM SIMM slot for coprocessing.
Advantages of such an add-on would be:
- avoids the PCI (133/266Mbps limits) bottleneck working at fast RAM bus
speed (2,7 to 3.2Gbps!)
- reconfigurable at run-time (load coder, record your favorite channel, load
transcoder, record from camera, filter, edit and burn to CD, ...)
- low power consumption (0.4 W per Gops/sec versus PC's ~ 20 W per Gops/sec)
so no noise, no fan!
- seems already linux/beowulf compatible (a great mythTV back end solution
- sure more like could expand a P4 2.8GHz oldie :-)

To be verified, I just notice XBox houses Xilinx's Vertex chips, box being
composed with:
- GeForce3: 76 GFLOPS at 200MHz
- xGPU: originally rated 140 GFLOPS at 300MHz
- Pentium III: 2.93 GFLOPS at 733MHz
- GeForce3 has 1 vertex shader, and xGPU has 2 vertex shaders. The rest of
the two chips are very similar

The values here can probably be divided by 2 or 3 as I assume those are
"peak theoricals".

Anyway, XBox FLOPS are all comming out from FPGAs where Vertex II are now on
the market.
I think 2GFLOPS are required to decode HQ MPEG-1/2/4, around 10GFLOPS to
encode, some more are required to transcode or filter realtime.

Any interests?

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