On 28.02.2009 11:42, Klaus Schmidinger wrote:
> What we also need is a way of detecting whether there are any ttxt subtitles,
> and on which page they are broadcast (haven't looked into the DVB standard
> about this yet, but I believe every broadcaster uses a different page).

The teletext standard defines a teletext subtitle flag that any subtitle 
page should have set. Specifically, its the C6 flag, placed at byte 11 
bit 8 of line 0 of the teletext page. (see cTxtReceiver::DecodeTXT of 
OSDTeletext on how to get that flag.)

However, I don't know how consequently this flag is used. The C5 
(Newsflash) flag also sets a transparent background, and could be used 
alternatively. Other transparent pages could also falsely set the C6 flag.
It also may be a good idea to interpret different teletext pages as 
different subtitles, in case a channel has more than one subtitle page.



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