[mythtv-users] Question about Closed Captioning

Daniel Kristjansson danielk at cuymedia.net
Tue Sep 18 19:34:55 UTC 2007

On Tue, 2007-09-18 at 12:23 -0400, Brian Walter wrote:
> Greetings,
> Where does Myth get the indication of closed captions?  Is it from the 
> stream itself, for from the guide?
> I'm trying to track down why CC seems to work sometimes, and not other 
> times.  Almost all programs indicate that they have CC, but, sometimes I 
> can get CC and sometimes not.  When toggling 'T', it will say CC 1 
> on...but...no captions.  Just wondering where the information for the CC 
> is coming from, and if I need to dig deeper into ivtv/myth/etc.

MythTV gets them directly from the stream. I believe you need to
specify the caption type for NTSC and PAL captions in mythtv-setup
in the General section for them to be recorded by the ivtv drivers.
ATSC captions are always recorded.

As for CC-1 & CC-3 showing up, these are always there when we don't
know if there are captions. NTSC captions don't provide the type
of information about themselves that ATSC captions do, with ATSC
we see a caption descriptor in the VCT or PMT and use this to tell
you what language the captions are in. With NTSC captions just arrive
whenever there are captions to display, if we waited for them before
showing the menu selections you could never enable NTSC captions
until after you had already missed some captioning.

-- Daniel

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