[Technologist]

two points ....
Firstly most vision mixing equipment does not pass the VBI ...or it it does it makes a mess of it
- e.g Mixing it or gated fading taking it to the new source later than you would like....
and if you can turn on "allow VBI" many people do not ...

Secondly video coding only codes the active picture
so in an ETSI (34Mbit/sec) codec the VBI is carried in a additional 2 MBit/sec E1 bearer
(NICAM Stereo is also in an E1.. or you use AES3 in E1)
You have to remember to turn them on and have the equipment each end to cope with it.

Incidently about 16 Line pairs of Teletext coded as MPEG 2 is about 25 Mbit/sec i.e 100 times its native bitrate