[mythtv-users] Myth 0.14 - Version 1.0??

[steve at nexusuk.org]

On Mon, 9 Feb 2004 papenfuss at juneau.me.vt.edu wrote:

> 	Nifty!  I didn't know there was such a hack.  I quick google for it 
> didn't reveal any promising links... where?

I'm not sure I'm afraid - I didn't really investigate since it was for the 
opensource drivers (although thinking about it, maybe we could hack the 
kernel to always makesure the interlace flag is set when using the closed 
drivers since it shouldn't really need cooperation from the drivers and we 
never want to run in non-interlaced mode?)

Infact, I just searched the Myth archives and found it: :)
	http://www.sr20.org/dvb/

If I'm bored at the weekend I might have a go at hacking the opensource 
part of the official nVidia drivers to see if I can force the card into 
interlaced mode, although the VESA code in that patch looks rather 
complicated...

> > Unfortunately on a non-NV card you can't do vsync, 
> 
> 	This requires GL as the output driver then, no?  I can't find a 
> reference to vsync in the Xv docs, but it's in the NVIDIA driver readme for 
> __GL_SYNC_TO_VBLANK.

AFAIK Xv doesn't support vsync at all.  Myth uses the /dev/nvidia0 device 
to trigger a frame draw at the right time.  Basically to do vsync the 
driver can do it 2 different ways:

1. Sit in a tight loop and poll the VGA registers - this will suck up a 
lot of CPU time so not really what you want for a Myth box

Or:

2. Include a kernel module that hooks the interrupt - much better way of 
doing it except practically no cards are supported kernel side ATM.  This 
is what the nvidia driver does.  I believe the DRM drivers do vsync, but 
AFAIK Myth doesn't support that yet.

-- 

 - Steve                                             http://www.nexusuk.org/

     Servatis a periculum, servatis a maleficum - Whisper, Evanescence