[x265] x265 and weighted P-frames

[Steve Borho]

On Fri, Feb 13, 2015 at 5:11 AM, Sami Inkinen <sami.inkinen at iki.fi> wrote:
> Hi,
>
> I just did a small test with the latest x265 version. It seems that weighted
> P-frames are not being used at all according to the log. Is this a bug or is
> it intentional?
>
> Best regards,
> Sami
>
> C:\x265>c:\x264\x264pipe.exe -y4mp c:\x265\hotfuzztest.avs   |
> c:\x265\x265.exe --y4m --input - --sar 1:1 --colormatrix "bt709" --colorprim
> "bt709" --transfer "bt709" --preset slow --crf 20 --output
> f:\temp\captures\x265.h265
> avs2pipemod[info]: writing 1220 frames of 24000/1001 fps, 1280x528,
>                     sar 0:0, YUV-420-planar progressive video.
> y4m  [info]: 1280x528 fps 24000/1001 i420p8 sar 1:1 unknown frame count
> x265 [info]: HEVC encoder version 1.5+9-7a42ca02d198
> x265 [info]: build info [Windows][GCC 4.8.2][64 bit] 16bpp
> x265 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX AVX2
> FMA3 LZ
> CNT BMI2
> x265 [info]: Main 10 profile, Level-3.1 (Main tier)
> x265 [info]: WPP streams / frame threads / pool  : 9 / 2 / 4
> x265 [info]: Internal bit depth                  : 10
> x265 [info]: Coding QT: max CU size, min CU size : 64 / 8
> x265 [info]: Residual QT: max TU size, max depth : 32 / 1 inter / 1 intra
> x265 [info]: ME / range / subpel / merge         : star / 57 / 3 / 3
> x265 [info]: Keyframe min / max / scenecut       : 23 / 250 / 40
> x265 [info]: Lookahead / bframes / badapt        : 25 / 4 / 2
> x265 [info]: b-pyramid / weightp / weightb / refs: 1 / 1 / 0 / 3
> x265 [info]: Rate Control / AQ-Strength / CUTree : CRF-20.0 / 1.0 / 1
> x265 [info]: tools: rect rd=4 psy-rd=0.30 psy-rdoq=1.00 deblock sao signhide
> tmv
> p
> avs2pipemod[info]: finished, wrote 1220 frames [100%].
> avs2pipemod[info]: total elapsed time is 483.321 sec [2.524fps].
>
> x265 [info]: frame I:     18, Avg QP:14.97  kb/s: 10066.85
> x265 [info]: frame P:    352, Avg QP:16.74  kb/s: 5525.69
> x265 [info]: frame B:    850, Avg QP:21.67  kb/s: 1980.48
> x265 [info]: global :   1220, Avg QP:20.15  kb/s: 3122.67
> x265 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
> x265 [info]: consecutive B-frames: 15.1% 7.0% 17.6% 53.5% 6.8%
>
> encoded 1220 frames in 491.19s (2.48 fps), 3122.67 kb/s

Responding to the x265-devel mailing list, please address questions to the ML.

WeightP (and WeightB) are adaptive, meaning they are only used when
the encoder believes they will be beneficial, which generally means
they are only used when the content has gradual lighting changes.  The
algorithm determined that the sequence you tested with would not
benefit from weighted predictions.

-- 
Steve Borho