[mythtv-users] TV-out settings for old PAL TV using Intel 945

Richard Taylor rjt-mythtv at thegrindstone.me.uk
Tue Dec 16 10:59:35 UTC 2008


I have a frontend with Intel 945GM video. I am trying to drive a 10 year
old PAL TV using a S-Video->composite cable. I know that this is not
going to get me great quality but I think that I should be able to
achieve something as good as analoge TV through the HF arial and the OSD
should look as good as any other settop box connected in the same way

I can get a picture but it is rubbish. To be more precise, the TV
playback is OK but the images does not fill the screen (I have cycled
through using 'W' but even 16:9 the native size leaves about 3cm border
and there is shape distortion at the top corners). OSD is very poor,
flickering and the text looks like every 10th pixel is missing).

I have spent many hours trawling web sites and the ML archives trying to
work out what I need to setup to get a reasonable picture.

There appears to be a number of variable that need to be correct:

1. modeline - xrandr lists a number of 'native' resultions but I am not
sure which is the 'best' to use or how to match them with the resolution
settings in the Myth setup. I have also tried to load in different
modelines recommended on various web sites but xrandr complains and will
not use them. I am also having problems getting the card to switch to
PAL mode (details below).

2. playback profiles
(http://mythtv.org/wiki/index.php/Playback_profiles) I think that my box
will nearly handle "High Quality" but should I use this for an old TV?
Which is the 'best' setting for an old TV? Setting it to 'High Quality'
does give reasonable results but is this the correct setting?

3. screen settings
 should the GUI Height/Width be set to the same as the resolution
selected for the display by xrandr? Should I be trying to change the
fonts or something else to improve the OSD?

Are there other settings that I need to get correct?

Output from xrandr -q -verbose

TV connected 1024x768+0+0 (0x51) normal (normal left inverted right x
axis y axis) 0mm x 0mm
	Identifier: 0x3e
	Timestamp:  3001205
	Subpixel:   unknown
	CRTC:       0
	CRTCs:      0 1
	BOTTOM: 37 (0x00000025) range:  (0,100)
	RIGHT: 46 (0x0000002e) range:  (0,100)
	TOP: 36 (0x00000024) range:  (0,100)
	LEFT: 54 (0x00000036) range:  (0,100)
		supported: NTSC-M       NTSC-443     NTSC-J       PAL-M
		           PAL-N        PAL
  1024x768 (0x51)   26.9MHz *current
        h: width  1024 start 1025 end 1088 total 1120 skew    0 clock
        v: height  768 start  769 end  800 total  801           clock
  800x600 (0x52)   17.0MHz
        h: width   800 start  801 end  864 total  896 skew    0 clock
        v: height  600 start  601 end  632 total  633           clock
  848x480 (0x53)   14.5MHz
        h: width   848 start  849 end  912 total  944 skew    0 clock
        v: height  480 start  481 end  512 total  513           clock
  640x480 (0x54)   11.3MHz
        h: width   640 start  641 end  704 total  736 skew    0 clock
        v: height  480 start  481 end  512 total  513           clock

xrandr --output TV --set TV_FORMAT PAL
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  153 (RANDR)
  Minor opcode of failed request:  21 ()
  Serial number of failed request:  31
  Current serial number in output stream:  31

Any suggestions would be much appreciated.


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