Proposed Changes to ULE text - Format descriptors for SI signalling

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

The ULE Spec is now completing IESG review, and will soon be ready for 
publishing as an RFC. With this in mind, the authors of ULE have progressed 
with registering a code-point for the SI that describes ULE.  They propose an 
update the ULE Spec to include the appropriate text describing this, prior to 
publication as an RFC.

As I see it, there are three threads to this process - ISO format_id; DVB 
data_broadcast_id; and stream_type.

Please send thoughts on any or all of the points below to the mailing list...

Best wishes,

gorry

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1) Format ID

Proposed additional text for ULE RFC to specify what to do with PMTs on page 3:

Old:
  "The MPEG-2 specification [ISO-MPEG2] requires conformant TS
   Multiplexes to provide Program Specific Information (PSI) for
   each stream in the TS Multiplex. Other MPEG-2 based transmission
   standards may also define Service Information (SI)."

New:
  "The MPEG-2 specification [ISO-MPEG2] requires conformant TS
   Multiplexes to provide Program Specific Information (PSI) for
   each stream in the TS Multiplex. Other MPEG-2 based transmission
   standards may also define Service Information (SI).

  "A format_identifier value has been registered with the SMPTE RA
   [ULE1], for ULE. This has the hexadecimal value 0x554C4531
   ("ULE1"). Transport Streams that utilise the Programme
   Map Table (PMT) defined in ISO 13818-1 and that use the ULE
   format defined in this document, SHOULD insert a descriptor with
   this value in the PMT ES_info descriptor loop."

Add:
[ULE1] Registration for format_identifier ULE1, SMPTE Registration Authority, 
LLC, http://www.smpte-ra.org/ule1.html.

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2) Data broadcast descriptor

Although this was proposed at the last IETF meeting and via the mailing list, 
this has not currently been progressed. We can not currently see a specific 
need for this descriptor for ULE streams - the conventional use of the 
descriptor for MPEG Tables makes this less appropriate than (1) as a 
general-purpose method. A registration for ULE could still be done (before or 
after publishing the ULE RFC). Is there a need to do this now?

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3) Stream Type

As I understand, stream_type values are not normatively assigned by ISO, but 
conventions are documented by DVB and ATSC. We propose to continue to progress 
with requesting a value for ULE (starting with ATSC). It is not clear to me 
that the value needs to be specified in the published RFC - what do others think?