[Openchrome-users] Linux Media Centers and frame buffer vs. Xorg

[Lasse Bigum]

Hi,

This is slightly off-topic for a list on hardware drivers, but
considering the number of people using their VIA machines for media
centers, I thought it would be a useful addition to the wiki.

My question is this:
What is the advantages and disadvantages, respectively, of using the
frame buffer or using Xorg for TV-out?

I understand from [0] that a PAL TV can display a native resolution of
720x576, and that by using this exact resolution, no scaling would be
needed, and this is thus the optimal resolution to run on non-HD TVs?

The closest that the frame buffer can come to this resolution is 800x600
meaning that some scaling would be needed. I'm currently booting at
1024x768 resolution, and run Freevo at 800x600, meaning that there are a
big chunk of black around the edges. I guess by using 800x600 from the
beginning, this would be better?

As I run Freevo, and if I used the frame buffer in 800x600, what would
the disadvantages be?

Finally, there is also the case of hardware acceleration. I have a VIA
EPIA EN15000G (using the CN700 chipset). I understand (learned it two
minutes ago :)) that when using the frame buffer, this can be done using
DirectFB which apparently has hardware acceleration for some cards?

The quote from IRC is:
< zoolooc> with G400 DH + DirectFB, I'm running exactly at 
           720x576, that's one of the main reasons why the G400 output IS 
           SO GOOD
< zoolooc> recently, there is MPEG2 HW support for some 
           DirectFB applications, like the softdevice VDR plugin

If there is no support for the VIA chipsets in DirectFB, would it not be better to use Xorg, as there is support for hardware acceleration of MPEG-2 (and MPEG-4 for some of you lucky guys with other chipsets ;))?

I understand that a number of Linux Media Center projects exist, and the
following is just some of those which uses the frame buffer or Xorg:

Capable of running directly on the framebuffer:
Freevo [1]
MMS [2]

Capable of running using Xorg:
Freevo
MythTV [3]

Thanks in advance for any replies, I will try to fill some of this into
the wiki so that others may learn from this as well.

Regards,
Lasse

[0] http://www.kingcot.eclipse.co.uk/unichrome/unichromeTvOut.html
[1] http://freevo.sourceforge.net/
[2] http://mms.kicks-ass.org/wiki/index.php/Main_Page
[3] http://www.mythtv.org/
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