[mythtv-users] Question about Closed Captioning

Brian Walter blwalter at gmail.com
Tue Sep 18 19:40:58 UTC 2007

Daniel Kristjansson wrote:
> 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
Thanks, that makes sense.  I'm thinking I've got something going on with 
the source (pvr150 seems okay, pvr500 seems to have problems)...but, at 
least myth *believes* theres CC in the stream, which helps.


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