"ule" and last byte

[alain.ritoux@6wind.com]

Precision about the "ule" method wrt the last byte

The sentence (p11)
"If the TS packet carrying the final part of SNDU has either
0 or 1 byte of unused payload, the encapsulator will start
transmission of the next SNDU in a new TS packet".

I think it is to allow enough room for the payload pointer,
is this correct, or is there any other motivation ?

Does this includes the payload pointer ?
I mean :
  (MPEG_HDR)(End of SNDU-A)[1 byte left] ==> OK send it now
but, in the following case
  (MPEG_HDR)(End of SNDU-A)[2 bytes left]
it will become, with a SNDU-B
  (MPEG_HDR)(Payload Pointer)(End of SNDU-A)(start SNDU-B)
                                            ^^^^^^^^^^^^^^
                                             Only 1 byte !
so, was it to be sent at once, or is the second TS cell legal ?
because in the second case, it would mean that the SNDU length
is not yet available, until a second TS cell is received, which
is not really a pleasant thing.

1) If having the SNDU length split over 2 cell is a pb, then the
sentence should more replaced with something like :

"If there is not enough room in a TS packet to put the first
2 bytes of an SNDU (possibly due to the needed payload pointer),
the encapsulator will start transmission of this SNDU in a new
TS packet. The remaining bytes, MUST be set ...."

2) if such a length split is not a pb, then first sentence is a bit
hard because, in case of multiple SNDU in a single TS cell, there
is not the payload pointer pb :
  (MPEG_HDR)(End of SNDU-A)(SNDU-B)[1 byte left]
OK keep it, because SDNU-C can start in this TS_cell :
  (MPEG_HDR)(End of SNDU-A)(SNDU-B)(start SNDU-C)
                                   ^^^^^^^^^^^^^^^
                                      1 byte
hence the sentence could be rephrased into something like
"If the TS packet carrying the final part of SNDU has either
0 or 1 byte of unused payload and the PUSI bit clear, the
encapsulator will start transmission of the next SNDU in a new
TS packet".
so it would relax the condition when PUSi bit is set, i.e.
there won't be other payload pointer added.


I would prefer solution 1)
Your thoughts ?

Regards.
Alain.
--
Alain RITOUX
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Fax +33-1-39-30-92-11
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