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10th March 2015, 23:56 | #1 | Link |
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Closed & Unvariable GOP (keyint)
Hello comrades, I require a small clarification if you would be so kind as to assist.
The conundrum is as follows: I want to make a Closed GOP video per YouTube Advanced Encoding Settings. However in the x264 config I am presented with two choices: --keyint --min-keyint , there is also an option to set GOP Calculation to Fixed or FPS Based. My intention is to set the GOP to 30, unvariable. If I set Maximum and Minimum GOP size to 30 the command line outputs -keyint 30 --min-keyint 16, if I set 0/30 it makes --keyint infinite --min-keyint 1, 30/0 makes --keyint 30 --min-keyint 1 With that considered the question is as follows: how to make "Closed GOP. GOP of half the frame rate."? |
11th March 2015, 03:33 | #2 | Link |
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They simply mean do not use --open-gop and set --keyint. Leave --min-keyint at default.
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11th March 2015, 04:09 | #3 | Link | |
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Join Date: Jun 2012
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I wuz gonna say the same, but you beat me to it:
Quote:
There's no need to force any minimum GOP size IMHO. You want to allow x264 to start new GOPs at scene changes as it normally does. Since there is no "default" or "auto" minimum in MeGUI, I would set min GOP to 1. EDIT I see you have set --tune-zerolatency; this does nothing for you as far as YouTube goes - it's for live video. Last edited by raffriff42; 11th March 2015 at 04:29. Reason: zerolatency |
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11th March 2015, 11:51 | #4 | Link | |
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Two cents from my side - min-keyint may be useful to brake scene detection (as such scenecut and pre-scenecut can be controlled separately).
AFAIR GOP size advised for H.264 is around 1 - 1.25 second Quote:
Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream DVB Document A157 March 2015 |
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11th March 2015, 13:11 | #6 | Link | |
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Quote:
btw in headends without statistical multiplexing (i.e. most of stream based headends) adaptivity may be not optimal as it is not controllable and frequently lead to mux overload - usually fixed GOP & CBR can provide better results in such environment as less stuffing may be reserved to accommodate VBR (average video quantizer will be lower) - for adaptive headend you need to have reencoders... Last edited by pandy; 11th March 2015 at 13:15. |
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11th March 2015, 19:24 | #7 | Link | |
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Quote:
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Tags |
gop, keyint, youtube |
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