[Ffmpeg-cvslog] CVS: ffmpeg/libavcodec motion_est.c,1.115,1.116

[Michael Niedermayer]

Hi

On Fri, Dec 30, 2005 at 12:15:29PM -0800, Corey Hickey wrote:
> Corey Hickey wrote:
> > Michael Niedermayer wrote:
> > 
> >>btw, if you want you could try to replace 
> >>all 'c->scene_change_score+= s->qscale' in motion_est.c
> >>with 'c->scene_change_score+= s->qscale*N'
> >>where N is a interger between 1..16 (16 should be the old, 1 the new)
> >>according to my tests 1 was best overall on my files but the differences
> >>at the low values where small (all IIRC as i cant check that ATM), so 
> >>maybe we should increase it ...
> >>you could also try different values for scene_change_threshold ...
> >>allthough 6h encoding for each case maybe a serious problem, my files
> >>where all short <=2min 
> > 
> > 
> > Well, I have a script running now that will test the various values in
> > this order:
> > 4 8 12 16  2 6 10 14  1 3 5 7 9 11 13 15
> > 
> > If and when I see a trend I can kill the script and narrow it down.
[...]
> 1 (the current default), 2, and 4 look pretty much the same.
> 
> At 14 and 16 I see some high-motion scenes that benefit from receiving
> an I-frame, but other places that have high motion but not enough to
> trigger an I-frame look worse.
> 
> At 10, 12, and 8 (to a lesser extent), I can't find the scenes that get
> another I-frame, and other high-motion scenes still look worse.
> 
> 6 looks nice. I can't find anywhere that looks worse, and the
> high-motion scenes with extra I-frames still look much better.
> 
> 
> I don't know how universally applicable these tests are, but if 16 was
> default before and 1 is default now, adjusting to somewhere toward the
> middle is probably a safe change. I've attached patches for ffmpeg and
> mplayer, if anyone else wants to test this. If the patches should be
> applied, I'll make a patch for the mplayer man page. Otherwise, 6 could
> just be hardcoded.
> 
> 
> I haven't tried sc_threshold yet. My understanding is that using

can you achive the same improvement with sc_threshold? if yes the patch
is rejected, if no the patch is ok and can be applied

[...]

-- 
Michael