[Hexus] GPU-accelerated video-encoding. Who is better, AMD or NVIDIA? - Overclock.net

rico2001 · 3 Weeks Ago

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GPU-accelerated video-encoding. Who is better, AMD or NVIDIA?

Introduction

Since the release of DirectX 10 along with Vista back in 2007, and compatible GPUs such as AMD’s Radeon HD 2900 XT and NVIDIA’s GeForce 8800 GTX, the hardware capability has been there to offload many more general-purpose computing (GPGPU) tasks than was possible with DirectX 9.

We’ve looked at one such general-purpose task, video-encoding, back in December 2008, where we tested AMD’s revamped AVIVO video converter application.

Looking for a cross-company performance comparison, finding applications that support GPU-accelerated encoding for both manufacturers has been rather elusive. Thankfully, a couple of companies, CyberLink and Roxio, have agreed to work with both AMD and NVIDIA's GPGPU technologies, and it’s now possible to conduct a fair comparison between the two.

Source

thegreatsquare · 3 Weeks Ago

I can't recall where the review is or what it's called, but ATI is a little faster and Nvidia had better overall image quality.

This was pre-5000 series, but it was this year.

Coma · 3 Weeks Ago

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Looking for a cross-company performance comparison, finding applications that support GPU-accelerated encoding for both manufacturers has been rather elusive. Thankfully, a couple of companies, CyberLink and Roxio, have agreed to work with both AMD and NVIDIA's GPGPU technologies, and it’s now possible to conduct a fair comparison between the two.

Except not... the languages being completely different, this is more down to the programmer than the hardware. You can compare AMD CPUs vs Intel CPUs only because it's the exact same (compiled) code running in both cases, so it's down to the hardware (assuming no processor-exclusive optimizations were used).

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The resolution, too, is lowered to 720p.

It's 1000x562.

If you look, their CPU encoding screenshots have huge differences, when they should in fact be deterministic and thus bit-exact... IMO that completely invalidates this test.

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It spits out 29fps whereas it should have been 25fps, most likely due to the progressive-scan nature of the source material.

No, just bad programming...

And in the GPU comparison segment, the biggest mistake:

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Not only does the CUDA-accelerated output maintain greater fine-detail quality in the video but it also displays much better contrast.

Anyone ever use Photoshop? Have you played with the Levels filter? Yup, that's where this difference comes from. See, most videos have a luma level range of 16-235 (TV), where the value 16 is considered to be #000000 (black) and 235 is considered to be #FFFFFF (white). PC video has a level range of 0-255 (0 is black, 255 is white), and so, it has to be scaled from 16-235 to 0-255 so that the blacks and whites are where they should be. If this is not done, then the video looks washed out (dyed gray), because the blacks are assumed to be at 0 while they're actually at 16, and so they are closer to white than they should be. The opposite happens with the whites - they're assumed to be at 255 while they're actually at 235, so they're closer to black than they should be.

This is almost never an encoder error (because it shouldn't care about the level range), so... probably playback error on the author's side (read: he changed something which made it like this).

Credit should be given where credit is due, but this time it's not.

AMD
NVIDIA

Full size is attached.

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Indeed, the NVIDIA output appears to maintain so much more detail than the CPU-encoded output that it leads us to believe the CUDA codepath is not using the same coding parameters - and may even be using a more compute-intensive encoding engine.

WHO WOULD'VE THOUGHT?

lordikon · 3 Weeks Ago

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Originally Posted by thegreatsquare

I can't recall where the review is or what it's called, but ATI is a little faster and Nvidia had better overall image quality.

This was pre-5000 series, but it was this year.

If I remember right, it was the other way around.

trueg50 · 3 Weeks Ago

Here's the only part of the article that matters:

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The difference in image quality between the output from the CUDA-accelerated encode and the ATI Stream-accelerated encode is substantial. Not only does the CUDA-accelerated output maintain greater fine-detail quality in the video but it also displays much better contrast. Indeed, the NVIDIA output appears to maintain so much more detail than the CPU-encoded output that it leads us to believe the CUDA codepath is not using the same coding parameters - and may even be using a more compute-intensive encoding engine.

It should be noted, however, that the final image quality of the GPU-accelerated output file varies hugely, dependent on the source footage fed into MediaShow Espresso. This was made blatantly obvious when we analysed the image quality of the output files created from a different HD feed. AMD came up trumps by offering a much cleaner (albeit slightly softer) output than the NVIDIA's.

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Originally Posted by thegreatsquare

I can't recall where the review is or what it's called, but ATI is a little faster and Nvidia had better overall image quality.

This was pre-5000 series, but it was this year.

That would likely be the Anandtech article on Badaboom vs Avivo. They did a better job by completely ignoring Nvidia vs ATI in terms of speed, and instead compared them separately, and doing some image quality and bug comparisons.

Kryten · 3 Weeks Ago

I saw Nvidia having better quality both times.

thegreatsquare · 3 Weeks Ago

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Originally Posted by trueg50

That would likely be the Anandtech article on Badaboom vs Avivo

I finally found it, it was PCper. Taken together, Nvidia seems proven to be better in the image quality department.

wolf2009 · 3 Weeks Ago

I knew Coma would have something to say on this matter. Thanks, some very valid points

Kryten · 3 Weeks Ago

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Originally Posted by lordikon

If I remember right, it was the other way around.

Nah, that's the right way around. Nvida was slower, jsut, and had better quality. ATI was faster and had poorer quality.

The only difference a 5800 series card would make is the speed. the avivo programming itself would need an overhaul to make the quality better.

kz26 · 3 Weeks Ago

Nevertheless, if render time wasn't an issue people would take CPU over GPU-based video encoding any day. The quality of GPU encoding just still isn't up to par. Look at x264, for example!

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[Hexus] GPU-accelerated video-encoding. Who is better, AMD or NVIDIA?

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