[Ffmpeg-devel] qprd and frames being stuck at high quants

[Michael Niedermayer]

Hi

On Sat, Nov 18, 2006 at 05:13:03PM +0100, Baptiste Coudurier wrote:
> Hi
> 
> Michael Niedermayer wrote:
> > Hi
> > 
> > On Thu, Nov 02, 2006 at 11:42:53AM -0800, Corey Hickey wrote:
> >> Michael Niedermayer wrote:
> >>> Hi
> >>>
> >>> there where some bugreports aout $subj a long time ago, but all the
> >>> sample videos seem to have dissapeared, if that bug is still happening
> >>> for anyone, then please upload a sample source file which causes it
> >>> (with command line options ...)
> >> No problem with high quantizers so far, but I did find a possible small 
> >> usability bug. When encoding with vqmin=1:lmin=1, qprd appears to be 
> >> nearly preventing the use of quantizer=1. At very high requested 
> >> bitrate, this makes the output bitrate and PSNR much lower.
> >>
> >> [...]
> >>
> >> When I play the output video with -lavdopts debug=1, the lowest 
> >> frame-level quantizer I see is 2. If I use debug=16, I see three blocks 
> >> with a quantizer of 1, out of the entire video.
> >>
> >> I can upload a sample video if you need, but I think it's reproducible 
> >> with any source.
> >>
> >>
> >> I know this is a rather minor issue, since encoding at such high 
> >> bitrates is rare, but I still thought it worth pointing out.
> > 
> > retry with mblmin=lmin
> > 
> > QP_RD activates adaptive quantization, which uses mblmin/max
> > 
> 
> Here I think there is a problem:
> 
> sample: test_motion_est.avi on mplayerhq.
> 
> ffmpeg -y -i test_motion_est.avi -b 15000k -flags +qprd -flags2 +ivlc
> -bf 2 -mbd rd -mblmin 1 -lmin 1 test.m2v
> 
> Many frames have q as 4 and some frames bump to 60 for all macroblocks

should be fixed

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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