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  1. Mr. Computer Geek dannyboy48888's Avatar
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    Hey folks,

    Maybe I am the only one with this problem, but in x264 when enable a crf encode of 17 i have to manually change the max quant to 21 instead of 51 to keep good frames in high motion scenes. in static scenes the quant drops to 10 (i understand why, make a HQ I frame for the rest to predict off of with no extra bits needed) so i dont mind that. If i dont change the upper quant end to 21 though the quant will go all the way up to 26 or so. is this normal at crf 17? if so will it hurt image quality. if not, is me limiting the quant to 21 really hurting the encode or is it just making my file bigger? Any feedback, tuning, or explaination would be great. I understand how x264 runs , just quant 26 seems a bit high to me for a HQ encode with no file size constraint. attached are some snaps of my settings
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  2. Mr. Computer Geek dannyboy48888's Avatar
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    the images



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  3. Try increasing your subme to 8 or 9, 5 is considered very low is you want decent quality encodes

    You have deblocking disabled, DCT decimate disabled, and trellis disabled, neither of which is recommended.

    Yes, your filesize should increase if you lower the qpmax, but even on very high quality encodes it doesn't matter if several frames have a high quant - more importantly it depends on which frames. If there is a high quant on the complex/action sequences, then you have a problem.

    BTW, x264vfw isn't offically supported and has been known to cause issues as stated many times by the developers - I suggest using the regular x264 cli version. There are many front-ends/GUI's for it.

    I've can't say that I've experienced a deterioration that you speak of with the max of 51 on action sequences with a low crf such as 17 or 18, but I rarely use x264vfw version. If anything, x264 (at least the cli version) tends to overallocate to action scenes, and underallocate to static/low quality scenes & fades.

    I would try the suggestions above first, but another option instead of changing the global settings would be to use zones or a qp file if you have a specific problematic scene
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  4. Mr. Computer Geek dannyboy48888's Avatar
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    thanks for the help . i got the cli and applied the following settings :
    --bframes 5 --b-pyramid --ref 5 --crf 18 --b-adapt 2 --no-deblock -A all --direct auto --weightb --merange 16 --subme 6 --mixed-refs --8x8dct --no-fast-pskip --trellis 0 --aq-strength 1.0 --progress --threads 2 --me umh --sar 1:1 --non-derteministic -o test.x264 script.avs

    i knw u said use subme 8 or 9 , but i dont have the horse powewr for that. if i understood you right i should enable trellis OR DCT decimate. I choose dct cuz death the sheep said only one should have it's hand in the kool-aid : p-skip trell, or DCT Decimate. anyhow my problem is fixed. if I mis-understood you or am doing something drastically wrong let me know please
    if all else fails read the manual
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