[x264-devel] Theora Ahead of H.264 In Objective PSNR Quality

[Panagiotis Issaris]

Hi,

On Mon, 2009-05-11 at 02:12 -0700, Jason Garrett-Glaser wrote:
> On Mon, May 11, 2009 at 2:02 AM, Panagiotis Issaris
> <takis.issaris at uhasselt.be> wrote:
> > Hi,
> >
> > On Thu, 2009-05-07 at 20:57 -0700, Jason Garrett-Glaser wrote:
> >> On Thu, May 7, 2009 at 7:25 PM, Jason Garrett-Glaser
> >> <darkshikari at gmail.com> wrote:
> >> > On Thu, May 7, 2009 at 6:30 PM, Jason Martens <cacepi at gmail.com> wrote:
> >> >> From Slashdot:
> >> >>
> >> >> http://tech.slashdot.org/article.pl?sid=09/05/07/2352203
> >> >>
> >> >> Let the debunking begin!
> >> >
> >> > Apparently they seem to have used catastrophically bad settings for
> >> > encoding.  I'm going to guess they just encoded idiotically with
> >> > ffmpeg without using any presets, thus using ffmpeg's quite broken
> >> > defaults.  I suspect this is entirely intentional.
> >> >
> >> > It isn't worth spending time "debunking" though; anyone dumb enough to
> >> > actually believe such a thing deserves the godawful quality Theora
> >> > will give them.  And when they get that godawful quality, if they are
> >> > still dumb enough to not realize they've been scammed by Xiph, they
> >> > deserve every last bit of suffering they will experience.
> >> >
> >> > Dark Shikari
> >> >
> >>
> >> And it turns out the problem was a bug in ffmpeg when writing the y4m
> >> file prior to PSNR measurement, cutting a nice 4db off of x264's
> >> score.
> >
> > Just out of curiosity, do you have a link to any info regarding this
> > bug? I've been looking at ffmpeg-cvslog and am on the regular
> > ffmpeg-devel list and haven't found it. Was it discussed on IRC or
> > somewhere else?
> 
> IRC and ffmpeg-devel ML.
> 
> 12:35 < CIA-33> ffmpeg: conrad * r18795 /trunk/libavcodec/ (8 files): Add a
>                 chroma_sample_location field to define positioning of chroma
>                 samples
> 12:36 < CIA-33> ffmpeg: conrad * r18796 /trunk/libavformat/yuv4mpeg.c: Use
>                 chroma_sample_location in reading/writing yuv4mpeg
> 
> Committed a few hours ago.
> 
> It isn't really an ffmpeg bug, since no PSNR tool should ever do
> interpolation for any reason whatsoever.

Thanks!

With friendly regards,
Takis