High Definition Processor Speeds?

Baloubic · Post by **Baloubic** » Mon Oct 24, 2005 3:12 pm

Hi, I have some thoughs on buildning myself a cool, quiet HTPC.
Only thing is, I want it to play 1080p flawlessly, in any format.

Now, before Blu-Ray and HD-DVD arrives, the predominant source of 1080p material is WMVHD. I assume we'll se lots of downloadable pirated HD-XVID and HD-DiVX when that time comes as well.

Microsoft states 3.0 Ghz pentium 4 is the minimum requirement to play 1080p wmvhd. Although requirements for not-so-compressed MPEG Blu-Ray/HDDVD will be much lower, I expect specs for other sources of compressed HD material(xvid/divx) will require roughly the same processor speeds as wmvhd.

My current setup is a Athlon 3200+ with a Radeon 9800pro. By installing patches and overclocking to 2.5ghz I was able to play wmvhd material smoothly.

My question is as follows:
What cpu-type can I use in my HTPC, and at what minimun clock frequencies? Intel pentium CPUs are too damn hot, but can AMD CPUs handle it without overclocking? (I know my athlon 3200+ just _barely_ did it). How do CPU stack up against each other when it comes to massive decompression of high definition material?

Thanks,
Baloubic

Mikael · Post by **Mikael** » Fri Oct 28, 2005 5:27 am

I'm no expert on these things (HD movies), but it seems as if dual core CPUs handle HD material much better than single core CPUs. With that said, I'd say that an undervolted Athlon 64 X2 3800+ would be pretty ideal for a quiet HTPC.

hofffam · Post by **hofffam** » Fri Oct 28, 2005 6:31 am

Dual core cpus have two, slightly slower cores than the fastest single core systems. They work best with workloads that can execute tasks in parallel. I'm hardly an expert on the decoding of mpeg video, but my guess is that current dual core processors might be marginal for this task. The dual core might let the system do other things at the same time very well, but the actual decoding task would sit on one processor running too slow. Microsoft's recommendation seems to indicate that the decoding task needs a fast cpu. The current Intel Pentium D cpus have a clock speed of 2.8 to 3.2 Ghz. I haven't looked at the AMD.

widman · Post by **widman** » Fri Oct 28, 2005 6:32 am

get X2 3800. It's much better from 1080p. Anyway you can't undervolt X2 3800. it's refused to set volt less than 1.1V.

widman · Post by **widman** » Fri Oct 28, 2005 6:41 am

hofffam wrote:Dual core cpus have two, slightly slower cores than the fastest single core systems. They work best with workloads that can execute tasks in parallel. I'm hardly an expert on the decoding of mpeg video, but my guess is that current dual core processors might be marginal for this task. The dual core might let the system do other things at the same time very well, but the actual decoding task would sit on one processor running too slow. Microsoft's recommendation seems to indicate that the decoding task needs a fast cpu. The current Intel Pentium D cpus have a clock speed of 2.8 to 3.2 Ghz. I haven't looked at the AMD.

when I tried this page www.apple.com/trailers for both AMD 4000+ and X2 3800, it is a huge different. I tried 720i. For X2 3800 a, it was get full 24hz all the time, but for 4000+ sometime it drop to 12hz.

After used both chips,-they are in the same price range-, In my opinion X2 is much responsive for internet browsing, better for video and other daily stuff. 4000+ better for gaming.

If don't game, X2 is the only choice.

kwong121 · Post by **kwong121** » Sun Oct 30, 2005 8:40 pm

I have a Pentium D 820 (2.8GHz) dual-core and it decodes 720p HD Quicktime at 24FPS no problem. For 1080p, after a fresh reboot, it can decode it at 24FPS also, although once in a while in some scenes it will drop to 14 or something briefly (don't know the reasons though).

Note because my monitor/video card can't display 1080p natively so the 1080p source is displayed at 1280x720. Because the source is 1080p so the decoding still happens at that resolution and therefore I still think it is a valid test. Feel free to correct me.

I used to have a P4 530 (3.0GHz) and it can do 720p at full FPS no problem but not 1080p.

BTW, the source used are Song With In A Song at 720p and 1080p.

My system:

Gateway 835GM
CPU: Pentium D 820
Memory: 1GB DDR2 dual channel
Mummyboard: D945GBI
Video: on board 950 with shard memory 128MB at 1280x1024 32bit
Harddisk: Western Digital WD2400JD-22HBC0 (250GB) SATA

mrk22 · Post by **mrk22** » Thu Nov 10, 2005 9:49 pm

hofffam wrote:I'm hardly an expert on the decoding of mpeg video, but my guess is that current dual core processors might be marginal for this task. The dual core might let the system do other things at the same time very well, but the actual decoding task would sit on one processor running too slow.

I'm no expert either, but I do know that my old dual processor system would use both processors when doing MPEG encoding , so maybe decoding can be done in parallel as well.

darthan · Post by **darthan** » Thu Nov 10, 2005 10:12 pm

Decoding video is one of those things where two cores (even on two CPUs) should give you massive benefits. This is because it is utterly predictable what the next step is that has to be done. Cores/CPUs can alternate decoding frames or whatever allowing a properly programmed decoder to use them very effectively. It seems that these decoders exist judging by the experiences of people around these forums and the recommendations given by Apple and such so dual is definitely going to be better for decoding HD video.

ckang008 · Post by **ckang008** » Thu Nov 10, 2005 10:40 pm

My Barton 2500+ @ 3200+ speed w/512 mb ram can run 1080p HD TV stuff very well.

nicov · Post by **nicov** » Fri Nov 11, 2005 1:15 am

I've built exactly that kind of HTPC. I bought an A64 3800 (S939), in combination with an NVidia 6600 video card.
The trick is to enable WMVHD hardware acceleration on your video card(search the net for instructions), this will help you more than buying a faster CPU. An NVIDIA 6600 or a Radeon X700 are the lowest end fanless video cards that support WMVHD accelleration.
You still need a fast CPU though.
My system runs the Alexander WMVHD 1080P demo very well. This clip seams to be particularly difficult to play back properly.

~El~Jefe~ · Post by **~El~Jefe~** » Fri Nov 11, 2005 9:33 am

hm. for a freaking cheap crap part in a ripoff 1400 dollar junk plasma I sell at my store, I do think that almost any cpu can handle hd content.

we arent talking creating massive images like Doom3 or half life2. jeez.

i would say it is more video card dependent and not cpu, and by that i dont mean speed but something like the poster above noted how the card should have acceleration on it for decoding.

9800 aiw pro I believe has it. im not sure but im guessing so (its basically an x700 in speed with more features)