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GPU speed and file size

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carmen emarda
GPU speed and file size
on Dec 12, 2016 at 6:41:03 am

refer topics

Hello, Pros

Here is my result.

4min FHD data for rendering using Mainconcept preset of internet 1080 HD (mp4)

CPU Only 21min
OpenCL 21min
CUDA 8min

I am very happy to buy GTX580 now.

BUT There is some strange result.

Only CUDA rendering result to 170MB data size while others over 400MB.

Can anybody comment about rendering codec and file size result?

Thanks in advance.

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László Kovács
Re: GPU speed and file size
on Dec 12, 2016 at 1:04:43 pm


Here's a 3 cam shot. (
Total playing time: 02:25
Sources: 50fps FHD AVC (25 Mbps) from JVC HM600 (2X)
25 fps AVC (25Mbps) from Canon XA10
Effects used: Color Curves on JVC material; Color curves, Color correction on Canon material,
Levels on video output.

The target is first 25fps FHD, mp4: Mainconcept AVC/AAC (25Fps, 15Mbps Average 22Mbps max), because this is the template I use mostly. It derives from the builtin "Internet HD" template 😉
So the results:

Render time using OpenCL: 01:38 (~0.6 X realtime) resulted in 276MB filesize
Render using CPU only: 06:59 (~ 2.8 X realtime) resulted in 355 MB filesize.

The 2 files have visually the same quality. For me it looks like the OpenCL render does more respect to the template settings, as the CPU only render resulted in approx 19Mbps average bitrate, which is slightly lower than the 22Mbps maximum. I really did not change anything in the template, just the "Render using: " part.

I also did the same test for builtin Inernet HD template (only changed the framerate to 25 fps, because I don't want to render to 29.97 fps from a 25P source ☺ )

Render using OpenCL: 01:36 (filesize 221 MB)
Render using CPU only: 06:54 (filesize 293 MB)

CPU: i5 -3570; GPU: AMD Radeon 6970.

Best regards

László Kovács

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