H.222.0 Descriptors Query

[thatsmohitag]

Hi,

Subclause 2.6 of H.222.0 mentions the following Descriptors.

1)Target Background grid Descriptor

2)Video window descriptor

3)System Clock Descriptor


Can anybody tell me where are descriptors placed whether in PMT,PES or somewhere else??
Which of these Descriptors are Mandatory?

Thanks
Mohit

[Guest]

The descriptors are located in the PMT for transport streams and the Program Stream Map for program streams.

[thatsmohitag]

Are these Descriptors mandatory in PMT

[Guest]

For the basic transport layer specification, no descriptors are mandatory, because the specification says they "may be used".

But broadcasters each have their own practices, and so for a given broadcaster some descriptors may always be used, and so may be regarded as "mandatory" in that broadcast.

In practice, I rarely see your listed descriptors in PMTs.