[sugar] video bleeds through somewhat between sessions
Fri Aug 1 20:03:06 EDT 2008
On 01/08/08 15:00 -0400, Mikus Grinbergs wrote:
> G1G1, Joyride 2241. In one Terminal session started mplayer -- it
> was playing a movie. Went to another Terminal session, and entered
> some commands. Noticed that not all of the text on that screen was
> equally distinct - some of it was paler than others. Noticed that
> *which* text was paler changed from second to second. Realized that
> the paler text in the second Terminal screen corresponded to the
> *brightest* areas of the movie frame then being shown in the first
> Terminal screen (the one I had switched way from).
Video is muxed to the visible screen through the use of a color key -
given a rectangle of some size, the hardware compares all of the pixels
in that rectangle against a set color - if they match, then a pixel of
the video frame is shown, otherwise not.
The color is specified by the video application - most applications use
very saturated colors similar to those used in "green" or "blue" screens.
My favorite is hot pink (0xFF00FF). IIRC, mplayer uses an off-shade color
of grey, so it is easier to run into the possibility that other applications
will match the color key, especially with automatic shading such as
Nothing to worry about - just a fun little side effect of video
Systems Software Development Engineer
Advanced Micro Devices, Inc.
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