Are the video performance characteristics of a machine with a pci nvidia card (say a FX 5200 or 6200) much different than an AGP machine? I am adding a new frontend to my network to drive a new HDTV and can use either a 2.8 pci or a 2.6 agp... I know the agp slot is faster but enough to offset the processor difference? I am running an Air2pc HD5000 on my backend. Thanks.

_________________
nbdwt73

For mythtv either bus will have plenty of bandwidth. The agp bus performance is utilized, for instance, when playing games and large amounts of textures are loaded in and out of video memory.

The pci bus is capable of transferring 133 MB a second. Thats 478.8 GB an hour. More than enough for HDTV.

If you can you may want to swap CPUs that way you can have both agp and your best cpu. If your buying a new card I would get a 6200 AGP that has both DVI and componet Video outputs. here is one that will work well and is fanless:
http://www.newegg.com/Product/Product.a ... 6814127203

Also you may need to run XVMC Hardware decoding to get smooth play back. The 5200 and 6200 both support it.

Let's think about this a second.

The video card gets the image data AFTER it is decompressed. By the time it sees the data, we have full image resolution, i.e. 1920 x 1080 x 30 pixels per second. If each pixel is represented by 24 bits (1 byte each for RGB) the data rate is about 187 MB/sec.

Am I going wrong somewhere here?

I don't think I'd use a PCI card for HDTV.

(Oh, and I think both the 2.6 and the 2.8 machines are underpowered for displaying 1080i unless you have a tailwind, good luck, and success with XvMC.)

_________________
Do you code to live, or live to code?
Search LinHES forum through Google

Liv2Cod is correct, I didn't think it through.

Thanks for the correction.

Now you've got me thinking and I have a question.
When using xvmc it should be sending the compressed stream to the video card a and have enough bandwidth over PCI. Is this a correct?

Not that I would recommend someone being dependant on xvmc when there are other ways, just curios.


Thanks
Dan

1080i is interlaced so in theory it is actually half of 187mb/s

I still doubt hdtv will work on a pci gfx card...

Thanks for the input... I have a brand new HP SFF machine (2.8) that I was going to use but, as mentioned, has no AGP slot (odd thing is that most new SFF machines seem to be without...). I was concerned about that.

I have read several posts that 3.0 mhz is the least required processor but have seen several people with success with less... Given that I have a FE/BE system, I was hoping that would allow me to squeak by with the 2.8...

I will try this (since it seems the concensus is AGP is a requirement) with the 2.6 and report back.

_________________
nbdwt73

I tried to correct for this by calculating it as 1920 x 1080 x 30 instead of 60. That should be the total bandwidth of 1080i. If it were 1080p it would send the whole frame every 1/60 second instead of 1/30 second.

_________________
Do you code to live, or live to code?
Search LinHES forum through Google

Oh yeah lol. I thought 30 fps was ntsc but i just remembered thats only for movies!

I am looking for the best s-video or component out put to my large analog television with an older cpu. amd xp2600 with pc3200


I have been using a matrox g400 agp which does pretty darn good with pvr-250 recordings.

Now I want to playback hd-5000 hdtv recordings to the same tv but the cpu can't handle it.

Can I add an nvidia 5200 pci just for its avmc assisted mpeg2 decoding?
but still out put the hd video to my agp video card?

A long shot I'm sure.

My P4-2.8ghz hyper-threaded machine has enough power to playback either 720p or 1080i while simultaneously recording 1 HD show over firewire with a dct-6200 tuner box and recording another SD show via a PVR-250. However. I do not need to deinterlace my 1080i recording because my samsung HDTV accepts and deinterlaces 1080i signals. My 2.8ghz HT machine cannot always do this if I do the deinterlacing in software.

marc