Dieter wrote:
Well, some basic questions to ask ourselves:
1) What will it do? I personally think that a reasonable aim is decoding
video, hopefully even 720p/i or possibly 1080p/i, in real time (30+
fps),
while also providing a simple framebuffer and possibly audio. If
video is
the way to go, what formats?
1080p
Mpeg 1, 2 up to 80 Mbps
Mpeg 4 up to 20 Mbps ( Is this really the worst case? Seems low. )
H.264 up to 40 Mbps
H.264 is the killer. :-(
It is worse than just H.264, it has to be H.264 HiP 1080p/30! Only
dedicated hardware is a viable solution for that. Look at the size and
price of the first HD-DVD and Blu-Ray players. They probably are not
using a single chip solution for decode.
I like the idea of an FPGA,
See OGD1. Prototype being tested last I read.
The whole idea here is to try to use existing hardware as much as possible.
Any sort of DSP should also work.
This seems very promising if we can find a suitable one. The TI ones look
great except they aren't fast enough. Anyone know if/when TI is coming
out with a newer faster model? I think a couple recent posts had pointers
to other brands?
The DSPs for video decode are fixed point. For OpenGL, we need a
floating point so the fact that we can't get a DSP that will do the
video decode is not an issue. A DSP based card isn't going to decode
H.264 HiP 1080p/30
Do we need RAM?
We need RAM. IIRC the TI chips didn't have much if any built-in? I suspect
the other brands don't either. So we'll almost certainly need to add RAM.
3) What sort of interface? PCI? PCIe? USB? Ethernet?
OGD1 and OGC are going PCI-X/PCIe, so this project could go the other way
and use Ethernet. The TI chips have it built in, I'm not sure about the
other brands.
I think that most users will expect a PC expansion card. What types the
market currently demands is a good question. Yes, you can get around
this messy issue by using an external box fed by one of the three serial
interfaces.
4) What sort of output? DVI, s-video, S/P-DIF, etc.
DVI plus s-video.
New TVs aren't going to need S-Video.
What is S/P-DIF ?
Digital audio single cable.
It would be good to support component if we can.
Are there new TVs or monitors that have component (analog) that don't
have DVI or HDMI?
Question is, do we require DVI dual link? DVI single link is good
for 1080, but only up to 60 Hz. There is a strong possibility that
we will need to support 1080 at higher than 60 Hz. And there are the
3 or 4 people that have the spendy 30" displays that require dual link.
Most current wide screen monitors are 768 lines but higher resolution
ones will be coming. Currently, 1080 is only common on screens larger
than 32 inches. This issue might or might not be determined by the
chips we use.
5) What is the purpose? Is it designed as a media center, linux video
"savior", or what?
A video/graphics device that connects via Ethernet instead of a
card slot. No problems with AGP vs PCI vs PCI-X vs PCIe. No
problems with being out of slots, or having none to begin with
(e.g. laptops). Put the noisy computer in another room.
It makes sense to an engineer -- a box near the monitor or TV.
Can we convince users? Or could the same product be used both ways?
Module goes in a box with a power supply, or plugs into a PC expansion
card with system bus interface. This would cost more (unless the
economies of scale reduced the price) but has advantages both to the
user and to the manufacturer.
FLOSS "savior"? yes
media server? yes
X11 server? yes (would need keyboard and pointing device, but that
shouldn't be hard to add.)
Keyboard and Pointing device would be on the client. You would only
need to have them plug into the box if you were hiding the computer in
another room. IAC, you could just connect them with USB.
--
JRT
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