[XviD-devel] xvid + bframes and mplayer/ffmpeg decoding

[Michael Niedermayer]

Hi

On Monday 05 August 2002 21:42, Markus Liebl wrote:
> Hi,
>
> I played a bit with Edouard Gomez vbr module. It works very good, but I
> had to activate BFrames in xvid to get it work. After some encoding I
> wanted to watch the avi.
>
> Normally I use mplayer + libavcodec for decoding. This time I found two
> bugs, if I decode with libavcodec  and bframes are activated in xvid.
> (-vfm 3 / xvid decoder works fine)
>
> 1) green smearing bug
> If I use the default values in export_xvidcvs and a high bitrate, the
> movie gets more and more green. At low bitrates it is not visible :-)
>
> the picture is very dark, but the difference is visible ...
>
> with xvid decoder (vfm 3):
> http://www.fh-landshut.de/~mliebl/bug/vfm_3_green.jpg
> with lavcodec decoder (vfm 5):
> http://www.fh-landshut.de/~mliebl/bug/vfm_5_green.jpg
> movie (8.3 MB):
> http://www.fh-landshut.de/~mliebl/bug/greenbug.avi
IDCT bug, could someone from xvid team try to decode these with the reference 
IDCT? in libavcodec it looks bad with the simpleidct & the reference idct but 
looks ok with walkens IDCT, iirc xvid uses walkens idct (=libmpeg2 idct) ...

>
> 2) flashing blocks
> If I activate bframes ( -Q 1 ), I get flashing and jumping blocks at the
> border. At high bitrates I can see blue and green blocks.
> flashing blocks at bottom:
> http://www.fh-landshut.de/~mliebl/bug/flash1.jpg
> blue block:
> http://www.fh-landshut.de/~mliebl/bug/blue1.jpg
> movie (5.3 MB):
> http://www.fh-landshut.de/~mliebl/bug/blink.avi
bug in libavcodec, just fixed in CVS, thx for the bugreport ;)
note, there are still some blinking blocks in there, divx5 shows these too, so 
ill assume these are caused by a bug in xvid ... (havnt checked if these are 
vissible with xvid too)

[...]

Michael