Cpu vs Gpu rendering quality

7Seven

Newbie Joined: Dec 02, 2018 21:46 Messages: 14 Offline

Solved by

Sep 11, 2019 21:10

I have read in several forums that when you want the absolute best video quality you should do the final render with just the CPU and I was wondering if that is true?

I have done a few small test renders and there is a file size difference when you use the Hardware or GPU vs just the CPU for the render. So what do some of you more experienced editors say? Does the CPU only render give you a small but better render quality.

tomasc

Senior Contributor Joined: Aug 25, 2011 12:33 Messages: 6464 Offline

Sep 11, 2019 21:48

Quote I have read in several forums that when you want the absolute best video quality you should do the final render with just the CPU and I was wondering if that is true?

Yes that is true but I prefer smart rendering as in svrt to give the perfect video quality. Cpu rendeing is my second choice. The majority of users may see no difference between cpu and gpu rendering. Others use gpu rendering always to save time.

Depending on what is being rendered like hevc then gpu rendering is a must as unless it is a short clip. Let us know what you found in your small test. I am guessing that you do not see the value of quality versus time of cpu rendering to be worth it.

This message was edited 1 time. Last update was at Sep 11. 2019 21:52

JL_JL

Senior Contributor Location: Arizona, USA Joined: Oct 01, 2006 20:01 Messages: 6091 Offline

Sep 11, 2019 22:17

Quote I have done a few small test renders and there is a file size difference when you use the Hardware or GPU vs just the CPU for the render.

Then an issue someplace, one is specifying the end avg bitrate of the encode via the profile used, the end result should be similar. So, if things are configured the same and you have actual motion video, size will be about the same. If they differ, avg bitrate was not maintained which can lead to a quality issue.
2.489 GB GPU Encoded
2.492 GB CPU Encoded

Jeff

Transigence

Newbie Joined: Jul 01, 2019 01:01 Messages: 15 Offline

Jan 04, 2020 10:01

Quote

Yes that is true but I prefer smart rendering as in svrt to give the perfect video quality. Cpu rendeing is my second choice. The majority of users may see no difference between cpu and gpu rendering. Others use gpu rendering always to save time.

Depending on what is being rendered like hevc then gpu rendering is a must as unless it is a short clip. Let us know what you found in your small test. I am guessing that you do not see the value of quality versus time of cpu rendering to be worth it.

Just food for thought:
My GPU isn't capable of encoding HEVC, so if I want to use it, it must be done in software. If you're willing to spend the time, you can turn down the bitrate on an HEVC prodution quite aggressively and still maintain quite good quality. It's worth considering if space is an issue or of your viewers can be expected to have plenty of CPU power but short on network throughput. (HEVC is also more costly to decode.)