GPU Acceleration

diddleydoo

I have been trying to speed up my encoding after buying an nVidia GPU.

My PC has an AMD 1090T CPU (6 Core, 3.2 GHz) and a GeForce 460.

What kind of speed differences should I be getting between CPU decoding and encoding between CPU and GPU?

I don't see the message for active GPU when encoding or decoding H.264.....

I'm dealing mainly with Mpeg2 (DVD) and H.264 with AAC (My target Format).

Shane

terry5

Hi diddleydoo,
Please Open Fab click the Click the Green √ at top right corner of the DVDFab screen, and open Common Settings > General >A/V Codec, un-select "Disable all GPU codecs for decoding and encoding" and choose what you want to be used.
GPU is faster than CPU and more CPU resources are spared when using GPU acceleration.

Wish it helps.

diddleydoo

[QUOTE=terry5;100190]
GPU is faster than CPU and more CPU resources are spared when using GPU acceleration.
[/QUOTE]

I've been testing this yesterday and found that for 2-pass conversion, CUDA doesn't seemt obe used for H.264 at all.

If I do 1 pass with MPEG-2 on the CPU and H.264 on the GPU then I'm getting 250+ FPS converstion. Changing to 2-pass I get around 130 for each pass which is significantly lower than the 1-pass. Is this normal?

davecuk

I get more than a doubling of speed using a 460 card.

jbinkley60

[QUOTE=davecuk;100224]I get more than a doubling of speed using a 460 card.[/QUOTE]

I recently purchased an Nvidia GeForce card based upon the 560 Ti GPU. I saw full resolution Blu-Ray rips go from 18-20fps up to 55-70fps. I have an AMD 1090T w/16G of RAM. This was a huge jump in performance. 55-70fps for 1920x1080 resolution at 33mbs is screaming.

diddleydoo

Can anyone verify the issue with 2-pass recoding?

davecuk

[QUOTE=diddleydoo;100238]Can anyone verify the issue with 2-pass recoding?[/QUOTE]

he issue is that it's a waste of time if your going to encode using the GPU, far faster to simply one pass encode at a slightly higher bit rate if you want, rather than to do a software pass to find parts of the movie where there is more action (as it's quite slow) and then hardware encode. Plus I am not sure it even works properly, especially with GPU encoding.

I have done a 2 pass software encode and I could not really see any improvement, it just takes an awful lot longer.

diddleydoo

I see a big difference in many movies at 2200 kbps with one pass versus 2 pass.

My issue isn't a quality difference between 1-pass and 2-pass but rather why the 2-pass operation goes so much slower (even just considering the 2nd pass on its own) than a simple 1-pass.

As an example: The film Avatar I can encode from DVD to H.264 with audio copy in less than 10 minutes at 2200 kbps whereas a 2-pass operation takes about 40 minutes. Even the second pass ALONE takes 20 minutes, twice the amount of time as the one-pass complete operation.

The message that CUDA processing is activated does NOT appear at all during 2-pass encoding. I have the feeling it reverts automatically back to CPU processing for 2-pass.

This I don't quite understand.

terry5

Hi diddleydoo,
Firstly, 2-pass does not support CUDA encoding;
Secondly, 2-pass will calculate twice, which costs more time(as you said twice the amount of time as the one-pass) and provides high quality. What's more, you can see that, accurate account of the Encoding Method in Conversion Settings page, "Fast encoding(1-pass)" and "High quality encoding (2-pass)".

Wish it helps.

n__m

[QUOTE=terry5;100425] 2-pass will calculate twice, which costs more time(as you said twice the amount of time as the one-pass)[/QUOTE]

actually, he says that 2-pass is taking four times as long (10 minutes versus 40 minutes)

but if CUDA (and i imagine intel quicksync) isnt active in 2 pass then thats probably why its significantly slower.

diddleydoo

[QUOTE=terry5;100425]Hi diddleydoo,
Firstly, 2-pass does not support CUDA encoding;
Secondly, 2-pass will calculate twice, which costs more time(as you said twice the amount of time as the one-pass) and provides high quality. What's more, you can see that, accurate account of the Encoding Method in Conversion Settings page, "Fast encoding(1-pass)" and "High quality encoding (2-pass)".

Wish it helps.[/QUOTE]

Well I'm aware that 2-pass will inherently take longer than 1-pass. Quality and analysis doesn't come for free.

The point I was trying to get at was "2-pass does not support CUDA encoding". This was my suspicion but I had a hard time finding this out officially.

If this is so, may I ask why? Surely the encoding itself is similar (the second pass) to a 1-pass operation? What are the differences that CUDA can't be used for 2-pass but can for 1-pass. I have wasted my money on a nVidia GPUI in this case.

davecuk

I "think" that the hardware encoder is not able to have the feeds to cope with increases/decreases in motion within the movie and vary the encoding to suit. it just trucks along at whatever bit rate you have set.

I think you are probably better off from a speed point of view to set the bit rate a bit higher and use hardware encoding. If you want a compact high quality file, the 2 pass may be the way to go, however my experience at lower bit rates is that 2 pass or one pass does not make any difference. hardware encoding H.264 at lower bitrates is also fairly poor in quality terms and I prefer software xvid encoding at the lower bit rates (800 to 1000kbs).

Also DVDFAb software xvid encoding has typically been slightly worse than some other products I have used, but it's nearly twice the speed.

signals

I have never been able to detect any visible difference between a single pass and 2, especially on handheld devices.

terry5

Attention:
1-pass is for fast encoding and 2-pass is for high quality. They are not comparable for the speed. They are for two different points: Speed and quality.
1-pass, fast speed, using less time but not perfect quality;
2-pass, high quality, perfect quality but using more time.