Closed captions / Teletext support
In order to conform to international regulations, VLC needs to be able to decode the closed captions in TV, DVD, DVB and HDTV video. V4L has a CC api, DVD and HDTV usually have them in a seperate stream.
- Use ZVBI library for VBI decoding and image generation
- ESTI EN 300 472 for EBU teletext support in DVB
Perhaps look at Xawtv, dvbtext and other vbi, vtx systems.