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    Go Back   Doom9's Forum > Video Encoding > High Efficiency Video Coding (HEVC)

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    Old 1st November 2018, 02:02   #6481  |  Link
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    Quote:
    Originally Posted by LigH View Post
    What idiom would you give a configuration "beyond placebo"? Possibly "insane", like LAME MP3...
    ultra placebo. Or very placebo since that would match with very slow.
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    Old 1st November 2018, 05:10   #6482  |  Link
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    Quote:
    Originally Posted by TomV View Post
    When I was tuning x265's presets, I tried all of these options that go beyond placebo, to see what should be included in placebo. You and anyone else are welcome to try them again, but I found it was easy to massively increase encode times, but impossible to get any meaningful improvement in efficiency.
    Indeed. 摋me full 梒u-lossless?will tank speed unbelievably without even trivial quality improvements for typical content and use cases.

    I have seen visible and measurable value from ref 6, bframes 16, and tskip at <150 Kbps. Of course, using a lot of MIPS/pixel isn抰 nearly so painful at low frame sizes and bitrates.
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    Old 1st November 2018, 10:27   #6483  |  Link
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    Quote:
    Originally Posted by benwaggoner View Post
    Yeah, subme does have some impact on rate control, but --rd is where the action is at.

    From x265.readthedocs.io
    Well yeah, that's why I asked. As --subme in the x265 docs doesn't specifically mention RDO.

    But in x264 it's :-

    Quote:
    subme

    Default: 6

    Set the subpixel estimation complexity. Higher numbers are better. Levels 1-5 simply control the subpixel refinement strength. Level 6 enables RDO for mode decision, and level 8 enables RDO for motion vectors and intra prediction modes. RDO levels are significantly slower than the previous levels.

    QPel SAD 1 iteration
    QPel SATD 2 iterations
    HPel on MB then QPel
    Always QPel
    Multi QPel + bime
    RD on I/P frames
    RD on all frames
    RD refinement on I/P frames
    RD refinement on all frames
    QP-RD (requires --trellis=2, --aq-mode > 0)

    So it seems to me that --subme in x265 is as per --subme 1-5 in x264.

    And the RD stuff of x264 --subme 6-11 is branched off into it's own thing in x265 with selectable RDO levels, rd-refine as a separate option etc.
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    Old 2nd November 2018, 12:59   #6484  |  Link
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    x265 2.9+4-471726d3a046

    fixes: rowStat computation in const-vbv; memory reset size in dynamic-refine; linking issue on non x86 platform
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    Old 4th November 2018, 19:33   #6485  |  Link
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    Quote:
    Originally Posted by benwaggoner View Post
    Say, does anyone have any data showing potential benefits of using some of the "beyond placebo" settings?

    For example[LIST=1][*]--subme 6 or 7 instead of 5
    I don't know what data you're looking for besides "yes, it looks better." I wrote the following some months back in this thread:

    1) imo, if you care about things that move, (and picture quality in general), you have to use sub-motion pixel subme 7. 5 is good, and is as low as I ever set that even on files I'm trying to finish fast, but 5 is easily visually inferior to 7 imo. 7 of course takes longer to encode though.

    I'm usually around CRF 22-23 (with nearly all quality settings turned on). It probably has lesser effect at CRF 18.

    Last edited by Dclose; 4th November 2018 at 19:36.
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    Old 11th November 2018, 19:18   #6486  |  Link
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    For 2-pass encodes, I normally use a custom faster 1st pass command line which is the same as my slow 2nd pass just with RDO level and subme turned down to level 2, --me dia, --early-skip and --fast-intra.

    But I've been testing using identical command lines for both passes and using --multi-pass-opt-analysis instead which speeds up the 2nd pass considerably to the point where a complete 2-pass encode is almost the same speed as my usual approach.

    Which should technically yield the higher quality final result? Is there any potential harm to using --multi-pass-opt-analysis?
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    Old 13th November 2018, 17:52   #6487  |  Link
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    Quote:
    Originally Posted by RainyDog View Post
    Which should technically yield the higher quality final result? Is there any potential harm to using --multi-pass-opt-analysis?
    Don't forget to also include --multi-pass-opt-rps --multi-pass-opt-distortion to your command line as well.
    I understand that if your NOT turning down --RDO, --me and other settings then it should produce better results since it will spend more time on those settings in first pass. The --mulit-pass options are great in reusing the values obtained in the first pass to increase the speed of the second pass.
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    Old 15th November 2018, 04:09   #6488  |  Link
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    How does lambda and lambda2 tables work in hevc?

    Hi,

    I have some sample tabels for lamda2 and I generated a table of lambda based on it. This is the address of my sample https://mailman.videolan.org/piperma...ch/010936.html
    The second table is not related with its formula (lambda2 = 0.038 * pow(0.234, QP))

    is there any document or information that explains lambda and lambda2 tables and relations?

    Many thanks
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  • “创新从来都是九死一生”(人民论坛) 2019-02-14
  • 端午假期广州铁路运客640.5万人次 创历史新高 2019-02-14
  • 19次生态输水让塔河下游生机勃勃 2018-11-22
  • 男篮再胜伊朗迎热身赛两连胜 任骏飞19+11陶汉林18分 2018-11-22
  • 小卒子,你南街村的代言人啊?扮豬不咋像呢!你滴,大大滴,明白? 2018-11-22
  • 女性之声——全国妇联 2018-11-21
  • 新华网评:凝聚打赢脱贫攻坚战的强大合力 2018-11-21
  • 栗战书:执法检查要直面问题不搞评功摆好 让法律制度成为不可触碰的高压线 2018-11-21
  • 这些水果越新鲜越不能吃 放一放更好吃 2018-11-21
  • 生产资料公有制不会也不可能涉及生产资料的分配,这完全是你杜撰的,是强词夺理的。从这点看,你的所谓逻辑是幼稚可笑的。哈哈哈哈! 2018-11-20
  • 践行“两山论”是一场发展的革命 2018-11-20
  • 女教师舍身保护学生被撞身亡感动各界 2018-11-20