[mythtv-users] DVB subtitles comments

Paul Harrison mythtv at dsl.pipex.com
Mon Dec 26 12:49:18 EST 2005

----- Original Message ----- 
From: "Kim Wall" <kim at ductilebiscuit.net>
To: "Discussion about mythtv" <mythtv-users at mythtv.org>
Sent: Saturday, December 24, 2005 10:03 PM
Subject: Re: [mythtv-users] DVB subtitles comments

> Piers Kittel wrote:
> > subtitles on E4 (and I imagine, on other channels)
> > hasn't been fixed.  Or do I need to do something on my own end?
> > http://www.biased.org/misc/mythtv/P1010088.JPG
> > http://www.biased.org/misc/mythtv/P1010089.JPG
> I'm pretty sure that this is a result of the channel in question being 
> transmitted at a lower-than-usual resolution (E4, More4 and the minor 
> ITV channels spring to mind) to cram ever more into the available 
> bandwidth.  I assume the subtitles are transmitted with absolute pixel 
> offsets to specify their position, based on a full PAL image (presumably 
> this makes life easier for STBs).
> I suspect the blue bar is another symptom of the same thing - my 
> freeview STB likes to make green ones on More4 occasionally, and the 
> 'correct' fix is a bit of overscan.
> Kim.

The current DVB subtitle code makes no attempt to scale the subtitle images
which are scaled and positioned to be correct at a video size of 720x576. 
Some channels like E4 typically use a video resolution of 544x576 so when  the 
subtitle images are passed to the OSD for display the wrong position and image 
size is given for the video resolution being used. 

Could you try the attached patch and report back.

I'd be interested to know if DVB in NTSC land uses subtitles and if so are you seeing
similar problems with the subtitles displaying in the wrong position or partly of the screen.
Thanks, Paul
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