Opinions on AVC CUDA rendering quality?

Sebaz wrote on 10/1/2010, 5:42 PM
I use Vegas 9 Pro, and it seems that CUDA AVC rendering is coming to Vegas Pro 10. I don't have an NVidia card, but I would buy one if I knew that the quality is excellent. If anybody here used Vegas Studio 10 to render to 1080i AVC using the CUDA acceleration, could you please give me your opinions on the quality? I'm asking because AMD tries to sell the ATI Stream technology like it's great, but I tried it and it's absolute crap. So I would like to know if Nvidia's technology is any better before I spend any money on one of their cards.

Comments

Chienworks wrote on 10/1/2010, 7:11 PM
If i understand it correctly, Vegas won't use the card's software for the encoding. It uses it's own AVC codec, running on the card's processor. So your question hinges entirely on whether the codec was successfully ported to the CUDA chip properly without introducing any bugs that would affect the quality. Assuming this is the case then the quality will be absolutely identical. One could hope that the codec has improved since the previous version, but presumably this improvement would apply equally to both the CUDA version and the non-CUDA version.

The problems you had with ATI's Stream Technology weren't due to the ATI hardware, but because you used the bad software that came with it. One of the big problems with that software was that it originated back when processors were a lot slower so it had to take a lot of shortcuts to achieve real-time processing. More modern versions should take advantage of faster chips to do a better job, but i wouldn't hold my breath waiting.
Sebaz wrote on 10/2/2010, 9:56 AM
I also wonder if Sony's AVC encoder has been revamped for Vegas Pro 10, because in V9 it's very elemental, only CBR and allowing a few settings, but far from what other encoders allow, especially x264.

Either way, I would like the opinion of Vegas Platinum 10 users who have used CUDA cards to encode to AVC to tell me how much the quality suffers when encoding to 1080i compared to the original and compared to the encode to AVC without using the CUDA acceleration.

I did a test for a 5 minute file in x264. Using the --preset veryfast option, it encodes at 35 fps, which is good enough for me, but the quality suffers a bit. What I'd like to know is if CUDA can give me encoding speed that fast or faster, but with quality close to the original.
Chienworks wrote on 10/2/2010, 9:58 AM
Well, once again, CUDA is only going to affect the speed. The quality will be determined by the codec software used.