Intel PAL TV out on Aopen i945GMm-HL - slight chroma flicker on svideo output

[Justin Hornsby]

Hi folks.

I'm experiencing a slight problem with svideo out using the 'intel' 
driver version 2.1.

I eventually managed to find out how to use xrandr to set the TV 
standard to PAL and how to get the picture nicely overscanned with the 
margin setting options of xrandr but...

I've noticed that the svideo connection on my Aopen motherboard is 
flickering slightly near the top of the screen.  Turning the colour 
control on the TV down makes the problem go away which seems to indicate 
an issue with the chroma signal on the svideo port.  I quickly hacked a 
spare svideo cable up a little and found (by connecting the Y output to 
a composite input on the TV) that the chroma signal is also present on 
the Y pin.  It's my understanding that for svideo, only luminance should 
be present.  Depending on how the TV treats svideo internally, having 
chrominance on Y & C could cause problems.

I don't know anything about the TV encoder used on this board (yet) but 
I have access to video test gear at work where I plan to have a real 
good look at the signals coming out of the svideo port.  We also have 
good monitors which I know for sure don't do any quick & dirty tricks 
with Y&C signals so if the issue is one of 'beating' of the 'Y chroma' 
and C signals it should look nice & clean on there.

Are there any quick things I can try?  It seems (from a quick look in 
the driver code) that xrandr supports only TV_FORMAT & margin 
adjustments for the TV encoder.  All the timing values look sane to me 
but as I've already said I plan to examine the signals very closely at work.


Regards,
Justin