Re: Adaptation field use in ULE / MPG2-TS specification

[Gorry Fairhurst <gorry@erg.abdn.ac.uk>]

Just taking the second point, because the first is being debated in 
another thread...

Allison, Art wrote:

<snip>

> However, now that I glance at the header structure...to send this data 
> in TS packets, 'payload start indicator'  must be set to a value. It 
> is one bit, where 0= no PES start in this packet, and 1= PES or PSI 
> start in this packet. Suggest define that it be set to 0.
>  
> Art
> ::{)>
> Art Allison
> Director Advanced Engineering
> NAB
> 1771 N St NW
> Washington DC 20036
> 202 429 5418


Art, is this an issue, or is the current ID clear?

Section 3 para 2 onwards of:

http://www.ietf.org/internet-drafts/draft-ietf-ipdvb-ule-00.txt

says:

       The ULE encapsulation is limited to TS private streams only. The
       header of each TS Packet carries a one bit Payload Unit Start
       Indicator (PUSI) field. The PUSI identifies the start of a payload
       unit (SNDU) within the MPEG-2 TS Packet payload. The semantics of
       the PUSI bit are defined differently for PES and PSI packets [ISO-
       MPEG]; for private data, its use is not defined in the MPEG-2
       Standard. In ULE, the operation follows that of PSI packets. Hence,
       the following PUSI values are defined:
       
            0: The TS Packet does NOT contain the start of a SNDU, but
            contains the continuation, or end of a SNDU;
            
            1: The TS Packet contains the start of a SNDU, and a one byte
            Payload Pointer follows the last byte of the TS Packet 
header. 
       
       If a Payload Unit (SNDU) finishes before the end of a TS Packet
       payload, but it is not convenient to start another Payload Unit, a
       stuffing procedure fills the remainder of the TS Packet payload 
with
       bytes with a value 0xFF [ISO-MPEG2], known as Padding.