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Old 12th January 2021, 15:17   #9  |  Link
excellentswordfight
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Join Date: Jul 2017
Posts: 322
Quote:
Originally Posted by kolak View Post
I've noticed the same odd thing.
x265 (in ffmpeg) + g=1 causes speed to drop to single fps (where long GOP is way faster). Why is this the case?
x264 is very fast in I frame only mode. Why is x265 (3.3 version if I remember well) so slow?
Did you check thread utilization? Maybe the multithreading is not optimized for that scenario, and its working on one frame at a time.

Quote:
Originally Posted by easy2Bcheesy View Post
Yes, agreed. It's brilliant. The question is how I can actually integrate this into workflow. To begin with, I'm looking for a quick transcode using NvEnc that will have a tiny GOP (I guess) to ensure fast scrubbing. But this could be the basis of a much faster workflow generally.

Something else I've discovered - with Nvidia at least, HEVC decode is a ton faster than h.264 - and that's comparing keyint=1, x264 vs x265. Interestingly the file sizes are basically the same with the same CRF factor.
Not sure what settings that are possible to set with ffmpeg, have you tried https://github.com/rigaya/NVEnc ?

Sounds like it should be possible with -strict-gop & --gop-len

edit. What bitrate are you roughly using for this scenario with 2160p60? 100Mbps? 4:2:0 or 4:2:2? 8bit or 10bit?

And I wondered what happened to Sonys pro HEVC codec, weren't they working on an XEVC format? I would assume that there would be an all intra profile of that.

Last edited by excellentswordfight; 12th January 2021 at 16:47.
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