[MPlayer-dev-eng] [PATCH] synch to x264 r50

[Guillaume POIRIER]

Hi,
Le mer 29/09/2004 à 20:12, Loren Merritt a écrit :
> Adds a parameter 'scenecut', to control the threshold for inserting extra 
> I-frames.

>  .TP
> +.B scenecut=<-1\-100>
> +Controls how aggressively to insert extra I-frames (default: 40).
> +With small values of scenecut, the codec often has to force an
> I-frame
> +when it would exceed keyint.
> +Good values of scenecut may find a better location for the I-frame.
> +Large values use more I-frames than necessary, thus wasting bits.
> +-1 disables scene-cut detection.

In the attempt to provide users the best possible documentation, what is
suppose to happen is no scene-cut detection is done?
Are I-frames only inserted each every "keyint" frames?


On a side-note, I'm currently running mencgen on 3000 frames of an anime
scaled to 704:304, and so far, here are 2 interesting results:
Best quality (PSNR-wise):
bframes=1:cabac:deblock:frameref=3:fullinter:idrint=3:keyint=250:qblur=0.5:qcomp=06:subq=5
PSNR: Y=46.58, Cb=45.95, Cr=45.95, All=46.349
257.94 seconds

Fastest withing 1.0 (PSNR wise also):
bframes=1:cabac:deblock:deblockalpha=1:frameref=3:nofullinter:idrint=3:keyint=250:qblur=0.5:qcomp=06:subq=0
PSNR: Y=46.1, Cb=45.75, Cr=45.7, All=45.97
122.31 seconds

I'll let this test run during the whole night, it's currently à the 12th
step of 15 encodes each, so that's 180 different combinations that have
been explored already... Pffiou! That really eats up LOTS of CPU time!


I also ran 4 encodes yesterday to see the effect of fullinter and subq
on the same 3000 frames anime sample (ranked by PSNR):

bitrate=750
x264 [info]: PSNR Mean Y:46,00 U:45,43 V:45,42 Avg:45,79 Global:45,39
kb/s:749,7 fps:9,815

bitrate=750:fullinter
x264 [info]: PSNR Mean Y:46,07 U:45,47 V:45,46 Avg:45,85 Global:45,44
kb/s:749,7 fps:9,316

bitrate=750:subq=5
x264 [info]: PSNR Mean Y:46,17 U:45,51 V:45,50 Avg:45,93 Global:45,53
kb/s:749,7 fps:6,415

bitrate=750:fullinter:subq=5
x264 [info]: PSNR Mean Y:46,29 U:45,58 V:45,56 Avg:46,03 Global:45,62
kb/s:749,7 fps:5,579


I wouldn't draw any conclusions from those, other that, what a relief,
fullinter and subq seem quite effective, and fullinter being quite
"cheap", is maybe worth being activated on anime all the time.



Cheers,
Guillaume