Peter Kaczowka wrote:
The other problem is the bandwidth of the analog ATVEF data. I think its
maximum is (please correct me if I'm wrong):
2 bytes per line * 11 lines * 60 fields per second = 1320 bytes / second =
10.5 Kbits / second.
ATVEF-A is only line 21, 2 characters on the odd field only (even
field is XDS). So ATVEF-A is up to 2 * 30 bytes/sec.
But, look at the data being transmitted (turn your teletext-2
capability on your TV during the midday gameshows, such as "Jeopardy"
& "Family Feud"). They don't use the full bandwidth, and they assume
a separate internet connection. The ATVEF-A is just a bit more than
hyperlinks, timed with events in the show. I.e.: a question is asked,
a hyperlink leads the settop box to fetch the possible answers and
some javascript to keep score.
For ATVEF-B and NABTS, your bandwidth analysis looks correct, but I
believe the NABTS data contains up to 35 bytes per field, but I forget
where I read that. Still, as you say, the bandwidth is nothing in
comparison to what an mpeg stream can accomplish.
Chris
