I am going to build another home theater system, but this time with for HDTV. I currently use analog Hauppauge cards with hardward decoders. What I am trying to figure out is what is the right size processor for a good HDTV system. I know the NVIDIA video cards offer some hardware assist, but I am not sure if that impacts the picture quality or not.

So, what size processor should I use?
I see in many forums there is talk about 3GHz processor for HD and smaller if using video card hardware assist, but I need some clarification on this. Is it true that the HD data does not need to be encoded, thus it is already formated to be stored on the hard drive, which would not be demanding on the CPU? If so, this makes me think that a single tuner or dual tuner would not really be all that different if both were recording at the same time. I do see that encoding would require some processor power, but how about picture in picture, would that require additional processor power, or would it still be considered one picture to encode and present.

Then comes the question of dual core, how could this help or hurt. Any difference between Intel or AMD?

If my understanding of encoding and decoding is correct for a HD data, could I not use a smaller processor for a backend unit to do all recording and have a dedicated frontend just for decoding and play? Are there any units our there that could make a good frontend player? I have seen that some people use an XBox, but dont' know much about this yet.. Would an Xbox (older one) make a good dedicated front end for HD? or is there any other kind of unit like a playstation2 or something that could be dedicated frontend?

I would appreciate everyones input.

Thanks,
Bob

2.8 ghz or equivalent should be enough. The Dragon 1.0/1.1 uses an AMD 3200. It's enough for HD, but today, if I were buying, I'd use a dual-core. The Intel Core 2 Duo would be good, or AMD's equivalent. Not the hot/noisy dual-core Pentium D.
Heat is your enemy with any sort of STB, so hot chips are out.
You're correct in that HD doesn't need encoding. You could probably record 4 HD streams on a 1.0 ghz Celeron. But you couldn't play them back, nor would you have room for transcoding or commercial flagging. Many folks with 2.8-3.4 processors turn off commflagging during viewing hours, while those with dual-core systems can run everything at once.
Look at the specs for Dragon 2.0 at http://mythic.tv and you'll see what the current thinking is.

Ok... thanks for some input..

What about a 3Ghz Celeron or Semptron, the cheaper processors verses the non cheap processors? Does better processor type allow you to get away with a smaller processor speed. I have a notebook that has a AMD Turion64 dual core but only runs at 1.6Ghz. It has 5.1 and a GeForce 6150 video card, IR, and could make a great front end. Would the 1.6 be enough with the dual core?

As an experiment, I underclocked my 3.0Ghz (Usually runs 3.6) Prescott P4 to 2.4Ghz and it played HD with no issues. I didnt have time try it lower though. This was 1080i source, which AFAIK results in a a 1080P file.

I also am running an Nvidia FX5200, so perhaps XMVC (or whatever) is enabled. Im new to knoppmyth so I'm not sure.



HTH

I'm running an old athlon xp 2500+ at stock speeds, and haven't had any playback issues. I did however enable xvmc on a gforce 6200.

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R5F27, asus K8V, athlon64 3000+, Air2pc HD5000, nvidia 6200 agp 8x

Hey.. thanks for your comment. I have an xp2400 and am having trouble with playback on HD.. but as I am learning, it is should not be my machine capability.

Do you know how to view processor usage while using the system? I would like to lear this.

How about dual recording and playback of a recording at the same time? Have you tried this.

Here's a snippet of top during playback of 720p while recording a stream as well
Hope that helps.

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R5F27, asus K8V, athlon64 3000+, Air2pc HD5000, nvidia 6200 agp 8x

I was about to start a thread but found this thread which is similar to my question so I thought I'd just tack mine on.

I'm looking to build a an HTPC soon and want to be able to record two hd shows, commercial flag, and watch an HD show at the same time. From what I've read dual core's seem to be the way to go. I'd rather not spend the money on a core2 duo. It sounds like Pentium D's run hot and/or loud so AMD 64 x2 looks like my best option. Is the AMD Athlon 64 X2 3800+ Windsor 2.0GHz fast enough for my needs or do I need to go faster?

Along these lines, I'm looking for a non micro motherboard with 1 pci-e x16 slot, 4 pci slots and s/pdif out. The s/pdif seems to be the limiting factor. A lot of intel boards I was looking at fit my choices, but I could only find one amd board on newegg which was the ASUS M2V Socket AM2 VIA K8T890 ATX http://www.newegg.com/Product/Product.asp?Item=N82E16813131024

Is this a good board or is there something else I should look at?

thanks

As a general rule you should stay away from Via chipsets for MythTV. I think the real issues were back in the KT133 era chips but I'd still take a Nvidia chipset board over Via any day of the week.

Martian

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ABIT NF-M2 nView | Athlon 64 X2 3800+ | 2GB DDR2 800 | HDHomerun | GeForce 6150 (onboard) | WD 640 GB SATA HD | DVD-RW (sata) | StreamZap IR receiver with Logitech Harmony remote

Vizio 37" LCD HDTV (1080p)

the problem is that I can't find anything else with s/pdif, 3 or 4 pci slots, and 1 pci-e x16 slot.

Am I just not looking in the right places?