CPU vs GPU - whats more important for HTPC video quality?

[nikko1974]

Hey,

This is just a 'confirming my hunch' thread......but it seems that for quality video via one's HTPC that its FAR more important to have a capable CPU rather than a high end GPU.

Can people confirm this?

It seems that with most of the popular video formats at present all the decoding is done by software eg FFDSHOW, CoreAVC and therefore all the work is done by the CPU?

Especially if you've got any filtering or SPP fast blocking etc enabled or resizing.

The only caveat to this appears to be the hardware acceleration - which most of the GPU's currently have supposably on them - though how effective this is I'm not really sure.

But doesn't this GPU decoding only take care of a very small number of lesser formats? Except of course trust old MPEG-2.

And of course those playing BluRay need special GPUs as well? Is all their decoding done on the GPU?

I know a lot of this is prolly just speaking out aloud - so feel free to say - yes you're right or no you're wrong - but I am just trying to get this right in my own head.

So lower level GPU's combined with a good CPU would prolly be the best combo?

Oh and just finally.......I know with a CPU's cache its reasonably important with games - but how important is it for HTPC duties? eg is a 3ghz CPU with 1mb L2 cache essentially as good as a 3ghz with 8mb cache - as I know with desktop duties they're about the same.

Much thanks, sorry for blabbing.

[vlad]

Hi nikko1974,
Your Fluidtek anti-ad is just not on, really.
If you have some personal grudges against Eddie, we have heard it. There was an article about it(people like you), just relax and go forward. If you think that you are better than Eddie - be so. Bitterness and anger will not get you anywhere. IMHO
I have problems to reply to your posts - I don't want to promote your banner.
We should not use this forum to promote anything or demote anything. It is my strong opinion.

Back to the topic.
I have chosen the other way- best CPU and best GPU. Why not, you are building something for yoursef, and if you are not cash-strapped student, you can get a quad core CPU and 8/9 series Nvidia or 3800 ATI, memory is cheap, so get 4GB. MCE is important to me, why save on it. ?

[logifuse]

I'd say that GPU makes more of a difference than CPU. With the CPU, once you're passed a certain level (in rough terms, once the CPU usage is less than 50% during HD playback), there is no more that the CPU needs to do - it's beyond CPU cycles.

I'm trying an 8200 integrated GPU. No doubt that it's better than my 7050PV as it uses direct X 10 & shader model 4.0 (as opposed to DX9 & shader model 3.0), but I can't say that my 8500GT card is any better. Sure, the 8500GT is more powerful (e.g. you can enable anti-aliasing @ 16x, while you can't with the 8200), but the actual quality of the video is down to specific parts of the GPU (once you get past GPU based acceleration that lowers the CPU usage). The truth is that most of the branded GPUs have the same Avivo or PureVideoHD engine as their ATI or Nvidia siblings - you hit a wall with the processing of video content that isn't there with gaming (i.e. gaming - more power = better results, where for video playback, I think we're at or close to the limit).

Justin

[vlad]

Then I use my MCE to covert all crap I record to H.264
I record a lot of crap Just for WAF, and in case I want to watch it, for some insane reason. It takes a lot of CPU, cause I do it not overnight, but just after recording. With 4 cores I can do it.
Using my Palit 9600 Sonic I did not loose any frame, even on Blu-Ray.
Future proof.

[nikko1974]

Ah interesting.....I really didn't think that the GPUs were that important. I mean I really thought they were relatively limited in what they could do - but you explain it as actually being the other way around.

You certainly do learn something all the time in here.

Looks like I perhaps should have made the effort to try the 8600GT out rather than just put it down as too hard - oh well maybe tomorrow then!

Very interesting indeed....you certainly drop some nice morsels of wisdom.

[vlad]

As I say, I feel uncomfortable with you using this site to defame someone
If you will not stop, I will reply with message like this to your every post.

[nikko1974]

Originally Posted by vlad

Hi nikko1974,
Your Fluidtek anti-ad is just not on, really.
If you have some personal grudges against Eddie, we have heard it. There was an article about it(people like you), just relax and go forward. If you think that you are better than Eddie - be so. Bitterness and anger will not get you anywhere. IMHO
I have problems to reply to your posts - I don't want to promote your banner.
We should not use this forum to promote anything or demote anything. It is my strong opinion.

Back to the topic.
I have chosen the other way- best CPU and best GPU. Why not, you are building something for yoursef, and if you are not cash-strapped student, you can get a quad core CPU and 8/9 series Nvidia or 3800 ATI, memory is cheap, so get 4GB. MCE is important to me, why save on it. ?

Unbelieveable.....

1. FTR Its a pure coincidence I just removed it earlier this evening - but I will put it back now.
2. Thats been in my sig. for nearly a yr now - why you choose to bleet now is beyond me.
3. WHY do you feel the most appropriate way to address your personal problem with my signature is this?

So don't reply to my posts - I'll struggle on without your input.

You've obviously got a lil man love for Eddie - fair play to you - but don't come in like some high and mighty person and lecture me on something you know little about - if you had experienced what I had you'd not want others to endure it too.

Maybe you'd better brush up on your legalities ....warning people not to shop somewhere, as you've had a bad experience....and a pretty good bad one at that - is not defamation.

If you've further matters that you want to 'discuss' show some regard for the forums and also your supposed standing as a senior member and PM me instead.

FTR I'm sorry you feel this way - as until now I've respected your opinions and welcomed them - but your self-righteous diatribe is just too much - so please feel free to keep away from any of my posts and I'll be very happy to return the favour to you.

I apologise to other members that they had to have things slurried by such nonsense.

Thank you to Logifuse for his excellent response prior to Vlad's 2c worth.

[arkay]

Originally Posted by logifuse

I'd say that GPU makes more of a difference than CPU. With the CPU, once you're passed a certain level (in rough terms, once the CPU usage is less than 50% during HD playback), there is no more that the CPU needs to do - it's beyond CPU cycles.

I'm trying an 8200 integrated GPU. No doubt that it's better than my 7050PV as it uses direct X 10 & shader model 4.0 (as opposed to DX9 & shader model 3.0), but I can't say that my 8500GT card is any better. Sure, the 8500GT is more powerful (e.g. you can enable anti-aliasing @ 16x, while you can't with the 8200), but the actual quality of the video is down to specific parts of the GPU (once you get past GPU based acceleration that lowers the CPU usage). The truth is that most of the branded GPUs have the same Avivo or PureVideoHD engine as their ATI or Nvidia siblings - you hit a wall with the processing of video content that isn't there with gaming (i.e. gaming - more power = better results, where for video playback, I think we're at or close to the limit).

Justin

I'll just add a little more to it. Possibly wrong, possibly not, I'm no gfx card guru but for mine the decoding and subsequent quality of digital video has little to do with shader models and anti-alias settings. These things are great for gaming when smoothing vertexes or pixel stepping on digitally generated images but to my knowledge are not of any consequence to video decoding. It is true that the vector processing nature of 3D cards can and do help with the decoding and re-constituting of some parts of a compressed digital image. That being said it matters little if the CPU does it or the video card does. The only time it is of relevance is when the GPU is freeing CPU to an extent that you can get away with a lower speed CPU. If the CPU is less than 50% with no GPU assistance then you can't and won't get any benefit in picture quality if the GPU takes over and suddenly the CPU is using 30%.

The algorithm used is what can effect picture quality. Therefore the only difference in relevance of whether GPU assisted decoding has better PQ is based solely on the software being used. i.e. If Nvidia's purevideo decoder algorithm is better (on GPU) than a straight mpeg2 decoder (using CPU) that's one thing. But the same Nvidia algorithm using CPU would produce equally good picture quality based on code alone, not where it's executed.

The true nature of a video card is to display pixels on a screen in 2D. Irrespective of how that image was put together, any video card with enough bandwidth to shift 1900x1080x32 pixels 50 times a second is good enough to do full HD on any HTPC providing the CPU and relative memory bus bandwidth is fast enough to perform the decoding at the same rate.

Hope all that makes sense.

Cheers,

Arkay.

[nikko1974]

Sensational reply - thank you.

Going to have to read a few times and hope 'information osmosis' occurs..... :-P

[logifuse]

Originally Posted by nikko1974

Going to have to read a few times and hope 'information osmosis' occurs..... :-P

Me too.

What I was (unsuccessfully) trying to say is that for video playback, I think we've hit a glass ceiling. Bigger & beefier video cards & CPUs can't actually make the video quality much (any?) better, they can simply handle the processing with more head room. My rule of thumb nowdays is a mid level dual core CPU & an 8xxx series Nvidia card (8500GT is fine).

Most of the advances are aimed at & assist gaming, so Arkay's comment in another thread about no advances in video cards for video playback is fairly true. I will say that a more powerful GPU means that you can display HD video easier, so there is an advantage there, & changing to YCbCr444 makes a big difference on my TV, so that's an advantage too, but the actual picture quality hasn't changed much.

The difference between Nvidia & ATI is a different matter - I just can't seem to get a life-like image out of an ATI card, while others swear by it.

Justin