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Old 6th September 2013, 12:58   #1  |  Link
alexmineiro
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Join Date: Dec 2012
Posts: 6
x264 Partitions Question

Hi,

i have a question about the partitions of x264. I read on

http://mewiki.project357.com/wiki/X264_Settings#partitions

that p4x4 is generally not very useful and has an extremely high ratio of speed cost to resulting quality gain.

So which settings is the best.. actually i have this settings



Thanks

AlexM
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Old 6th September 2013, 13:35   #2  |  Link
sneaker_ger
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p4x4 is used by presets "slower" and following, so it probably isn't that inefficient. It does not make much sense to answer your question based on the little info you provided, because we don't know whether the rest of your settings are fast or slow. It does not make sense to arbitrarily combine fast settings with slow settings because the result could be inefficient, i.e. the cpu time might have been much better spend on other settings. Now before you post your settings you should probably just stick to the presets:
Code:
      --preset <string>       Use a preset to select encoding settings [medium]
                                  Overridden by user settings.
                                  - ultrafast:
                                    --no-8x8dct --aq-mode 0 --b-adapt 0
                                    --bframes 0 --no-cabac --no-deblock
                                    --no-mbtree --me dia --no-mixed-refs
                                    --partitions none --rc-lookahead 0 --ref 1
                                    --scenecut 0 --subme 0 --trellis 0
                                    --no-weightb --weightp 0
                                  - superfast:
                                    --no-mbtree --me dia --no-mixed-refs
                                    --partitions i8x8,i4x4 --rc-lookahead 0
                                    --ref 1 --subme 1 --trellis 0 --weightp 1
                                  - veryfast:
                                    --no-mixed-refs --rc-lookahead 10
                                    --ref 1 --subme 2 --trellis 0 --weightp 1
                                  - faster:
                                    --no-mixed-refs --rc-lookahead 20
                                    --ref 2 --subme 4 --weightp 1
                                  - fast:
                                    --rc-lookahead 30 --ref 2 --subme 6
                                    --weightp 1
                                  - medium:
                                    Default settings apply.
                                  - slow:
                                    --b-adapt 2 --direct auto --me umh
                                    --rc-lookahead 50 --ref 5 --subme 8
                                  - slower:
                                    --b-adapt 2 --direct auto --me umh
                                    --partitions all --rc-lookahead 60
                                    --ref 8 --subme 9 --trellis 2
                                  - veryslow:
                                    --b-adapt 2 --bframes 8 --direct auto
                                    --me umh --merange 24 --partitions all
                                    --ref 16 --subme 10 --trellis 2
                                    --rc-lookahead 60
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Old 6th September 2013, 13:39   #3  |  Link
alexmineiro
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Hi, this are my general settings:

Code:
--crf 20 --threads 0 --profile high --rc-lookahead 50 --qpmin 10 --qpmax 51 --qpstep 4 --ipratio 1.4 --pbratio 1.3 --chroma-qp-offset 0 --deadzone-intra 11 --deadzone-inter 21 --trellis 1 --min-keyint 25
--keyint 250--scenecut 40 --ref 4 --no-interlaced --deblock 0:0 --me umh --merange 16 --subme 7 --bframes 3 --b-bias 0 --direct auto --b-adapt 1 --b-pyramid normal --no-weightb  --open-gop --partitions all
--weightp 2 --level 4.1 --aq-mode 1 --aq-strength 1.0 --psy-rd 1.0:0.15 --cqm flat --output
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Old 6th September 2013, 14:36   #4  |  Link
LoRd_MuldeR
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You are not allowed to ask "what's best", because what is best depends on many things!

Anyway, with "--partitions" you only specify which partitions x264 will consider at all (and more of them takes more time). Still, x264 will pick the "most suitable" partition - from those that are under consideration.

So enabling "p4x4" in addition certainly shouldn't hurt, though the benefit may be relatively small. Which means it may not actually be worth the extra computation time.

If you just want the best possible compression (and encoding time doesn't matter that much), you can pick "--partitions all" and that's it. Apart from that, I recommend just sticking with the "--preset" system.
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Last edited by LoRd_MuldeR; 6th September 2013 at 14:40.
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Old 6th September 2013, 15:01   #5  |  Link
alexmineiro
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ok thanks.
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