[MEncoder-users] on psy_rd

[Grozdan]

2009/9/17 Matyas <mplayer.list at sustik.com>:
> Hi,
>
> Could someone in the know compare and comment on the two runs bellow.  It
> would hopefully help me understand the usage/benefit of various psy_rd values.

psy-rd lowers PSNR and SSIM while subjectively increases quality so
you shouldn't trust these metrics too much while using psychovisual
options like adaptive quantization and psy-rd. I don't really know
what you want us to comment about. I always use psy-rd of 0.8:0.2 and
all looks good to me. Also you should use b-adapt=2 and lower bframes
to something like 4 or 5

>
> Run A:
>
> x264 - core 68 r1189 9d0b5e9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2009 -
> http://www.videolan.org/x264.html - options: cabac=1 ref=4 deblock=1:0:0
> analyse=0x3:0x133 me=umh subme=6 psy_rd=0.5:0.2 mixed_ref=1 me_range=32
> chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 chroma_qp_offset=-3
> threads=3 nr=0 decimate=0 mbaff=0 bframes=9 b_pyramid=1 b_adapt=1 b_bias=0
> direct=3 wpredb=1 keyint=300 keyint_min=25 scenecut=40 rc=crf crf=22.0
> qcomp=0.70 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.40 pb_ratio=1.30 aq=2:1.00
>
> x264 [info]: SSIM Mean Y:0.9840352
> x264 [info]: PSNR Mean Y:44.007 U:45.326 V:48.183 Avg:44.647 Global:43.967
> kb/s:531.89
>
> run B:
>
> x264 - core 68 r1189 9d0b5e9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2009 -
> http://www.videolan.org/x264.html - options: cabac=1 ref=4 deblock=1:0:0
> analyse=0x3:0x133 me=umh subme=6 psy_rd=0.0:0.2 mixed_ref=1 me_range=32
> chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 chroma_qp_offset=-1
> threads=3 nr=0 decimate=0 mbaff=0 bframes=9 b_pyramid=1 b_adapt=1 b_bias=0
> direct=3 wpredb=1 keyint=300 keyint_min=25 scenecut=40 rc=crf crf=22.0
> qcomp=0.70 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.40 pb_ratio=1.30 aq=2:1.00
>
> x264 [info]: SSIM Mean Y:0.9841399
> x264 [info]: PSNR Mean Y:44.013 U:44.822 V:47.703 Avg:44.535 Global:43.821
> kb/s:466.48
>
> The source was 10 minutes long (a sample from a progressive DVD).
> Thanks.
> Matyas
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