[MEncoder-users] new doom9 codec comparission (submission)

Michael Niedermayer michaelni at gmx.at
Sat Dec 17 19:17:22 CET 2005


On Fri, Dec 16, 2005 at 04:27:14PM -0500, Rich Felker wrote:
> On Thu, Dec 15, 2005 at 12:12:38PM -0800, Corey Hickey wrote:
> > > In the past, Michael asked me repeatedly to use libavcodec for all codecs. 

hmm, i remember that i wanted the same decoder to be used for all mpeg4
codecs a long time ago as in some comparission lavc was compared with 
ffdshow and pp disabled against other mpeg4 codecs with their own decoders 
with pp enabled (their decoders may actually not have had an option to disable
 pp), also note thats how i remember it and my memory might be wrong, if so
please someone correct me

> How far in the past? These issues weren't known until September 2005.
> BTW here are screenshots of XVID decoded with both XVID IDCT and
> ffmpeg's default mpeg4 idct:
> XviD: http://img39.imageshack.us/img39/3341/154xvid6xt.png
> libavcodec: http://img39.imageshack.us/img39/4590/154avcodec2da.png
> XviD: http://img39.imageshack.us/img39/6135/283xvid3tg.png
> libavcodec: http://img39.imageshack.us/img39/573/283avcodec5xl.png
> As you can see, the ones decoded with the 'wrong' idct look bad in the
> same way (or at least a very similar way) that lavc mpeg4 looked bad
> in the doom9 tests!
> I am by no means positive that this is the problem, but I definitely
> think it's worth investigating more.

also please note that the idct used for encoding in lavc meg4 is as 
selectable as for decoding, so if we are being told before the test which 
decoder is used then someone could try all idcts to find out which works best


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