[MPlayer-users] maximum resolution: how to extend ?

[Reimar Döffinger]

On Thu, May 06, 2010 at 09:16:40AM +0200, Oliver Seitz wrote:
> 
> >> mplayer -quiet -demuxer rawvideo -rawvideo fps=10:w=2500:h=2000:y8
> >> /dev/zero -vo x11
> >
> > That one however is rather slow and cannot even do scaling in hardware.
> 
> Sorry for the bit of unrelated question in this thread, but if scaling
> isn't needed as the raw stream is in the right size, why does it make any
> difference in this case? It is an uncompressed video stream that has to be
> given to the display. Ok, the stream is y8, so each value has to be given
> three times to be RGB, but is there anything else that could be
> accelerated in such a case?

"Accelerated" maybe not (though you lose brightness and contrast adjustment
as well), but (unless -vo x11 could be modified to support grayscale directly)
you must convert it to RGB.
Converting to RGB mean reading the Y8 data, writing the RGB data and then
giving the RGB data to the X-Server.
Depending on RGB format, that would mean 5x - 9x the memory bandwidth
requirement - if nothing else that is quite a power waste, even if
your memory is fast enough to handle it (if the video is small enough
it should fit in cache and it wouldn't be a real issue).