[mythtv-users] Closed Captioning

[Daniel Thor Kristjansson]

On Wed, 24 Nov 2004, Brian Meehan wrote:
]I'm curious how Myth handles CC info. How does the stream come in? Is it
]encoded in the video signal, or is it text that accompanies it? I would like
]to be able to save off the CC text to a file along with each show. Has
]anybody tried this before? I saw a post from last year about this time on
]the mailing list, but it seems like it never got off the ground.

There are two ways, for frame grabber cards the data comes in from the 
/dev/v4l/vbi? devices, for MPEG cards the data is encoded in the MPEG2
stream. I believe myth currently handles the framegrabber cards. I've 
been working on the MPEG2 data, the patch is here:
  http://www.mrl.nyu.edu/~danielk/mythtv/

I believe this only works with ATSC streams however as the PVR-250 and 
PVR-350 drivers don't yet handle captions. Though I believe Hans Verkuil 
was working on this.

The code in libs/libmythtv/vbitext handles EIT-608 captions from the 
vbi device, and the code in the HDTV captions patch handles EIT-708 
captions in MPEG2. When EIT-708 captions are working I'll look at 
handling EIT-608 captions in MPEG2 streams.

-- Daniel