[mythtv-users] Resolution for PAL analgue TV

Craig Read craigread at csi.com
Tue Dec 14 04:09:36 UTC 2004

Phill Edwards wrote:

>>>> Yes, I believe that is the correct resolution for PAL.  Where exactly
>>>> are you setting this resolution - as you state below, X doesn't like
>>>> resolutions that aren't available on your video card.
>>> In the mythtv ASettings -->T Vsettings --> Recording Profiles --> 
>>> Software
>>> Encoders on the Image Size screen.
>> It sounds like that is where your cpu usage problem is.  I think the 
>> front-end will be trying to resize the output when it doesn't need 
>> resizing (because it's already at 720x576).  But what you've changed 
>> doesn't modify the resolution of your X output.  What I think you 
>> want to do is create an appropriate mode line in your 
>> /etc/X11/XF86Config-4 file to output X at 720x576.
> Thanks Craig. Just so I'm clear, then, are you advising that I leave 
> the settings in the Image Size setup screen as 480 x 480 (which I 
> think is the installation default)? 

Under Utilities/Setup->Setup->Appearance->Screen Settings, I have zero 
in all of the settings (GUI width, height, X offset and Y offset) and 
"Use GUI size for TV playback" is checked.  MythTV should then use 
whatever the resolution of X is (ie. 800x600) and my NVidia TV out then 
rescales to the 800x600 signal to 720x576 when it outputs as PAL (sort 
of the reverse of what Steve Cristall is getting).

If you set it up this way and change your X settings to output at 
720x576, there shouldn't be any rescaling at all from the input signal 
to the output signal.  I did try that, but (like Steve) I didn't get it 
working 100% and stuck with 800x600 (which works fine).

Some people have also said that they get a better picture when receiving 
a HDTV signal, even though it's being displayed in a standard def set.  
So changing your X settings to 720x576 might or might not improve your 
picture quality.

I don't think I've been using any of the recording profiles at all (all 
my profiles are still set at 480x480) and all of my video is still in 
720x576 when I watch it on another machine.  When I look under the 
recording profiles, I have "Hardware DVB Encoders" (I don't have a 
hardware encoder) and "Transcoders" as the only two entries (and I don't 
transcode anything).  I'm using a Twinhan VisionPlusTER (no hardware 
decoder) and I leave the video in the form it was recorded in until I 
burn it to DVD and/or delete it.

I think the recording profile you're using is most likely the source of 
your high CPU usage.


More information about the mythtv-users mailing list