Will Radeon 6970 Improve Render Time vs. Radeon 7850

[Dave Osbun]

Your CPU is what is slowing your render speeds down. AMD has never been known as a ‘great’ CPU for video editing.

Latest Intel i7 (even previous model) will give you much better results.

Dave

[Mike Kerr]

So if I get a radeon 6970 and use GPU for rendering, which MC AVC supports, it won’t make a difference?

[Norman Black]

Mainconcept AVC will support AMD 5xxx and 6xxx GPUs for encoding via their OpenCL encoder. 7xxx and newer are not supported by MC AVC but the Vegas video engine itself still works very well with newer GPUs.

GPU encoder algorithms are not typically at the quality level of CPU encoders. It all depends on the bitrate you are encoding to and the source material. Really, unless bitrates are low and you pixel peep you are not likely to notice. Do your own tests.

[Mike Kerr]

The bitrates I’m using I believe are 20k if I recall. If I had a card that MC supported, I’d be happy to do my own testing and share it. Unfortunately I only have the card I have, the 7850, which is why I’m asking if I did buy the 6970 for $100 if it would make a difference.

I’m not spending $100+ to perform a test… I know what I see right now, and if you’re telling me that I’d barely notice any quality drop-off with GPU encoding, then that’s good. But should I expect a render speed increase?

[Norman Black]

By 20K, I believe you mean 20 megabits. That is a very high bitrate for HD material. Most every encoder should look the same at that level. This includes MC AVC versus Sony AVC and even those versus x264. Sure PSNR and/or SSIM will show some differences, but the human eye at frame rate, I doubt it.

I once compared MC AVC OpenCL GPU versus my GoPro 1080p30 source file. Both 20Mbit. Pixel peeping a still frame between source and the re-encode was nearly identical. I had to toggle to see any pixel difference.

Back then I had an AMD 5850 GPU. These days I have an AMD 7950 GPU and so MC AVC is no longer an interest to me and I render using x264 via frameserving and encoding is the least of my worries as editing takes all my time.

[Stefan Jovanovic]

Could you please explain this part “and I render using x264 via frameserving”?
I’m just trying to figure out what it means.

[Scott Francis]

I am interested in what you mean by that as well!! “and I render using x264 via frameserving”?

Xavier (Scott) Francis
Mind’s Eye Audio/Video Productions

[Dave Osbun]

The improvement, if there is any at all, will be minimal. Replacing your current GPU isn’t really a fix when you have a system bottleneck (the AMD CPU).

[Norman Black]

[Stefan Jovanovic] “Could you please explain this part “and I render using x264 via frameserving”?
I’m just trying to figure out what it means.”

I use the “Debugmode Frameserver” utility render driver.
Then one installs Avisynth, or Avisynth+ into the system.
Then I use ffmpeg as the receiver of this whole process. ffmpeg directly support access to Avisynth.

Avisynth is the frameserver. Debugmode framserver is a go between between Vegas and Avisynth and ffmpeg is the encoder which basically receives from Avisynth.

With ffmpeg one can render whatever your heart desires. AVC/H.264 (via x2564), DNxHD, ProRes, XDCAM, Xvid and more. In whatever container file format you want. ffmpeg is a command line tool and not terribly easy to use.

I really only encode AVC for my use. x264 is the best quality and fastest encoder out there for AVC. In its superfast modes it is as fast as GPU encoders at similar quality and in its slower modes it generates better quality. Your choice.

Here is an example of my command script which executes ffmpeg. It is a slower quality encode.


@echo off

title encode crf25

cd d:\renders
d:

REM output the AviSynth commands
echo AviSource("server.avi") > server.avs
echo ConvertToYUY2(matrix="rec709") >> server.avs
REM echo ConvertToYUY2(matrix="PC.709") >> server.avs

c:\systools\ffmpeg32\bin\ffmpeg.exe -threads 0 -i server.avs -c:v libx264 -preset medium -profile:v high -me_method umh -crf 25 -colorspace bt709 -color_primaries bt709 -color_trc bt709 -pix_fmt yuv420p -bufsize 40M -maxrate 40M -c:a libmp3lame -qscale:a 2 -chunk_size 64K output.mp4

pause

del server.avs

REM saved commands for alternate audio output formats and bitrates
REM (mp3 160k vbr) -c:a libmp3lame -qscale:a 4
REM (mp3 192k vbr) -c:a libmp3lame -qscale:a 2
REM (aac 192k vbr) -strict experimental -c:a aac -q:a 2.4
REM (aac 192k) -strict experimental -c:a aac -b:a 192k


[Sonic 67]

[Mike Kerr] “I’m not spending $100+ to perform a test…”
Well… you could first sell your video card on eBay and make those $100.
Although, I wonder… you paid $600 for the editing software and you have no extra $100 for a video card?