[MPlayer-users] Xvidix : Distortion of large images.

[Anthony J. Ciani]

When playing a high resolution movie (800x600) using -vo xvidix, a
mottled green vertical bar was seen at the right side of the window.  This
bar was not present when using other vo devices.  Further testing showed
that the presence of the bar was not dependent on the encoding or content
of the stream, and only depends on the size of the image sent to the
xvidix device.  Using -vop scale=X:Y, any input file seems to be capable
of reproducing the behavior.  It was found that for any image with a width
greater than 720, the pixels beyond number 720 would be replaced with the
mottled green.  It was also found that heights greater than 1024 pixels
would also cause image distortions, indicating the maximum image size for
the xvidix device is 720x1024.

This seems to be a limitation in the current implementation of the xvidix
(or vidix) device, or the hardware, although the driver silently deals
with it, giving the impression that it's a bug.  This also appears to be a
bug in the people who made a 800x600 video, encoded with a bitrate
suitable for a 640x480 image, from a 720x480 source.  A work-around for
large images when using the xvidix driver seems to be the use of "-vop
scale=720", which prescales the image to a width of 720 before sending it
to the xvidix device.  This work-around has the drawback that the OSD and
subtitles do not display (why is that?).


MPlayer version: MPlayer 1.0pre2
Compiled with gcc3.2 20020903

Hardware:
Dell Latitude CPx J/650
CPU: Pentium III 650MHz
Video: ATI Technologies Inc Rage Mobility P/M AGP 2x (rev 64)
       Video memory 8 MB

Software:
OS: RedHat 8.0 (mostly)
    Vanilla 2.4.20 kernel
X:  RedHat supplied version 4.2.0-72
    Video driver: built-in ati driver (not Gatos)

-- 
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              Anthony Ciani (aciani1 at uic.edu)
           Computational Condensed Matter Physics
   Department of Physics, University of Illinois, Chicago
              http://ciani.phy.uic.edu/~tony
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