Low quality CUDA encoding

[apk]

Found that CUDA-enabled encoding is just horrible. It is really fast and useful in some scenarios (like desktop video capture), but when it comes to games - CUDA destroys all details except text.
Here's an example:
CUDA OFF:

CUDA ON:


Encoding settings are identical in both cases:

[vivan]

That's because GPU video encoding is just marketing. They are not capable of using all advanced algorithms that software encoder can use.
So they are fast, but have quality like mpeg-2.
Intel QuickSync is a bit better (in speed and quality) but still software encoders blow it away.

For instance, x264 has preset that has equal speed and quality. Guess what? It called "ultrafast".

[Carpenter01]

I dont have this problem, even on youtube, it has almost perfect quality. http://www.youtube.com/watch?v=ZZmHM8fFxPU

I can barely notice the difference between the raw video, and the rendered MP4.

[yic17]

Good to know .. I better try it out myself and see if there's any difference ..

[apk]

I dont have this problem, even on youtube, it has almost perfect quality. http://www.youtube.com/watch?v=ZZmHM8fFxPU
I can barely notice the difference between the raw video, and the rendered MP4.

NFS (and most of other car-sim games) are technically a scroller-type games. Most of the image you see is changing linearly and has low dynamic. That is why by complexity it can be compared to desktop recording. And this type of tasks are ok for CUDA encoding.

But try to encode some (MMO)RPG-type games where the content of image is changing intensively and randomly (walking and turning the camera around at the same time) and you will see that CUDA-encoder can't handle it the same way as software encoder does.

Check these example files of MMORPG gameplay encoded with and without CUDA acceleration:
CUDA OFF
CUDA ON
(each file is ~9MB size)
Higher resolution makes the difference even more noticeable.

[Nielo TM]

That's because GPU video encoding is just marketing. They are not capable of using all advanced algorithms that software encoder can use.
So they are fast, but have quality like mpeg-2.
Intel QuickSync is a bit better (in speed and quality) but still software encoders blow it away.

For instance, x264 has preset that has equal speed and quality. Guess what? It called "ultrafast".

GPU video encoding is much faster than CPU encoding and has the ability to provide higher efficacy. But it's not easy developing software to run on parallel processors.

It is why the adaptation of OpenCL, DirectCompute and CUDA have been slow.

[Carpenter01]

I dont have this problem, even on youtube, it has almost perfect quality. http://www.youtube.com/watch?v=ZZmHM8fFxPU
I can barely notice the difference between the raw video, and the rendered MP4.

NFS (and most of other car-sim games) are technically a scroller-type games. Most of the image you see is changing linearly and has low dynamic. That is why by complexity it can be compared to desktop recording. And this type of tasks are ok for CUDA encoding.

But try to encode some (MMO)RPG-type games where the content of image is changing intensively and randomly (walking and turning the camera around at the same time) and you will see that CUDA-encoder can't handle it the same way as software encoder does.

Check these example files of MMORPG gameplay encoded with and without CUDA acceleration:
CUDA OFF
CUDA ON
(each file is ~9MB size)
Higher resolution makes the difference even more noticeable.

Notice that this isnt my only video, i have over 150 videos, (some unlisted) and I havent experienced any kind of this degradation. I used Fraps, Afterburner, Asus Gamer OSD, and now Action. My Youtube Channel

[vivan]

I dont have this problem, even on youtube, it has almost perfect quality. http://www.youtube.com/watch?v=ZZmHM8fFxPU

I can barely notice the difference between the raw video, and the rendered MP4.

Are you kidding?
And that's 1080p downscaled to 1366x768 (I'm too lazy to download full video to make fullsize screenshot). Everything is blocky and blurry as hell.

GPU video encoding is much faster than CPU encoding

proof?
http://compression.ru/video/codec_compa ... arison.pdf starting from page 99.
x264 with "ultrafast2" preset is fastest there. "superfast 1-pass" has same speed and quality that Intel QS encoder.
And CUDA is even slower and has even worse quality...
And imagine speed of 6-core intel CPU

and has the ability to provide higher efficacy.

In video encoding "efficiency" is quality/bitrate. Hardware encoders are worst here, since software encoders could provide same quality at much (2x-4x) smaller bitrates.

But it's not easy developing software to run on parallel processors.

It's not the main problem. The main problem is GPU's architecture which is very ineffective for any compression.
In short: GPU has a lot of cores, that could do only one simple task with different data. E.g. multiplication of hundreds of matrices. But that's not what video encoding requires! For adequate quality it should use complex algorithms that GPU's couldn't run effectively because of its architecture. So only very basic algorithms are avaivable for GPU, that results in low quality. And there is not much to do with that.

GPU is like factory with thousand of stupid workers. That do everything using only their hands, they can't do complex task and they all can be trained to do only one task. So product quality is low. But since there are thousand of them - productivity is high.
CPU is like factory with 4-10 robots. They can do any task, than can work wery fast and with very high precision. So they can produce same product with the same low quality with the same productivity OR high-quality product with much lower productivity.

Still h/w is ok for encoding video for portable devices, but it shouldn't be used for final video encoding for video distribution (It is just disrespecting people that would download your video).
E.g. youtube use it for encoding their video. Now you now why they has such horrible quality And they are developing WebM, that has even lower quality at even bigger bitrate (I've tested couple months ago - for same video WebM version has +30% bitrate and lower quality).
On the other hand check vimeo... On the same video it has -20% bitrate and has much better quality.

But one of x264 dev's (DS) works with intel (but because of NDA he can't say much) and they are improving intel QuickSync hardware (= new chips, not software), so in future intel CPU's it should be a lot better (but still far from x264).

[Carpenter01]

I dont have this problem, even on youtube, it has almost perfect quality. http://www.youtube.com/watch?v=ZZmHM8fFxPU

I can barely notice the difference between the raw video, and the rendered MP4.

Are you kidding?
And that's 1080p downscaled to 1366x768 (I'm too lazy to download full video to make fullsize screenshot). Everything is blocky and blurry as hell.

Because its from youtube, which downgrade every videos no matter how high the original quality was.

But here's an other video, again this is youtube, so it wont be perfect.
http://www.youtube.com/watch?v=315EkHh6ZiY