[mythtv-users] teletext spacing ?

Andre mythtv-list at dinkum.org.uk
Sun Nov 21 09:34:30 UTC 2010


On 21 Nov 2010, at 07:36, Mark Kendall wrote:

> On 21 Nov 2010, at 02:02, John <reidjr at lineone.net> wrote:
> 
>> I am using "analogue" style teletext on dutch satellite tv for the subtitles (888).
>> 
>> I am using Mythbuntu 0.24-fixes, and although everything works, the text is really hard to read. The problem is:
>> 
>> Instead of looking like this the :  T h e   T e l e t e x t   l o o k s   l i k e   t h i s !
>> 
>> It is worse than monospaced font, its as if there is an extra space between every character. It happens on all my frontends, and with all fonts I've tried. Digital text / subtitles are fine.
> 
> That's because there IS an extra space between each character! Teletext uses fixed sized/spaced characters and hence there is no flexibility for enlarging captions. Broadcasters work around this by using the double height character code but clearly this doesn't increase the width. Rather than having horizontally squashed text, the norm seems to be to insert extra spaces to stretch the text.

Some of the original Teletext chips (Mullard SAA 5050 if I remember) used to show double width too when double height codes were used but spacing wasn't adjusted so everyone put extra spaces to avoid the every other char missing side effect! Plus it still looked passable on non saa5050 decoders, when software implementations of teletext came along this "feature" wasn't implemented, sadly the nicely anti aliased text (for the day) wasn't implemented either.

Far too much time spent tweaking teletext mode on the BBC micro combined with repairing early teletext boards, back when teletext was an expensive extra add in board or set top box :-)

Andre


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