jsmar

I believe this is incorrect. It took me a while to figure out where you may have gone wrong. I believe you are looking at the max number of groups per parade, which is 8. But as far as I can tell, you can have up to 112 parades. Of course that would only be feasible if each parade's PRC (parade repetition cycle) was 7, and each of those 112 (16 * 7) parades only used one group per subframe.

If you are looking for the maximum M/H bandwidth, it would be about double the number above. There are 16 slots per M/H subframe, and each subframe contains 156 TS packets. If the slot contains an M/H group then the M/H group uses 118 of the 156 packets, or 75.64% of the available bandwidth. There is no limitation on the number of slots that can contain an M/H group, i.e. all 16 slots can contain M/H groups.

I would note also that the number of groups can change from frame to frame (note - not subframe to subframe, i.e. each subframe within a frame must contain the same group layout), so categorizing an entire ATSC stream as containing a "number of groups" is probably not correct, although I am not sure in actual use if there will be any parades with a PRC value other than 1 (perhaps not for video, but I can easily see low bandwidth data doing this). I'm not sure if for example they wanted to allocate an average of 3.5 groups per subframe to a parade if they could set the number of groups for the parade to 7, but set the PRC to 2 (i.e. the parade would consume 7 slots per subframe in every other frame), or if setting the PRC to a value other than 1 is only for low bandwidth services that want to consume less than 1 group per subframe on average. I guess that would probably depend on the buffering standards for M/H video, which I have not looked at.