[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Proposed Changes to ULE text - Format descriptors for SI sign alling
Sorry, but I feel a need to be pedantic.
See ISO/IEC 13818-1 §2.4.1. A Transport Stream consists of "... one or more
programs ...". Also, "The Program Map Table, in Table 2-28, specifies,
among other information, which PIDs, and therefore which elementary streams
are associated to form each program."
Therefore, if there aren't one or more "programs" (defined as a "collection
or program elements", where "program elements" means elementary streams), or
if there isn't a Program Map Table that specifies which elementary streams
are associated with the (one or more) program(s), it isn't a "MPEG-2
Transport Stream". Just because it uses MPEG-2 Transport Stream packets,
that doesn't make it a Transport Stream.
Adam Goldberg
Director, Television Standards & Policy Development
Sharp Laboratories of America
8605 Westwood Center Drive, Suite 206
Vienna, VA 22182
(703) 556-4406
(703) 556-4410 fax
-----Original Message-----
From: owner-ipdvb@erg.abdn.ac.uk [mailto:owner-ipdvb@erg.abdn.ac.uk] On
Behalf Of Gorry Fairhurst
Sent: Sunday, July 31, 2005 7:24 AM
To: ipdvb@erg.abdn.ac.uk
Subject: Re: Proposed Changes to ULE text - Format descriptors for SI sign
alling
On 29/7/05 11:44 pm, "Goldberg, Adam" <agoldberg@sharplabs.com> wrote:
> Are there transport streams (in IETF-land) WITHOUT PMT?
Indeed there are.
There are many possible topologies for MPEG-2 Transmission Networks, see
section 3.1 of:
http://www.ietf.org/internet-drafts/draft-ietf-ipdvb-arch-04.txt
In some specific scenarios, there are "transport streams" that go straight
from the ipdvb gateway/encapsulator, are modulated/broadcast and then
received by a Receiver/Router (i.e., for example they are never
"remultiplexed", and have no specific need for a PMT). These can use other
methods to configure PID usage.
Gorry
> If so, I'd like to know. And if not,
>
> RTR: " A format_identifier value has been registered for ULE [ULE1]. This
32
> bit number has a hexadecimal value of 0x554C4531. Transport Streams that
> use the ULE format defined in this document SHALL insert a descriptor with
> this value in the Program Map Table (PMT) ES_info descriptor loop."
>
>
> Adam Goldberg
> Director, Television Standards & Policy Development
> Sharp Laboratories of America
> 8605 Westwood Center Drive, Suite 206
> Vienna, VA 22182
> 703-556-4406
> 703-556-4410 fax
> 571-276-0305 cell
>
>
>
>> -----Original Message-----
>> From: owner-ipdvb@erg.abdn.ac.uk [mailto:owner-ipdvb@erg.abdn.ac.uk] On
>> Behalf Of Allison, Art
>> Sent: Friday, July 29, 2005 3:06 PM
>> To: ipdvb@erg.abdn.ac.uk
>> Subject: RE: Proposed Changes to ULE text - Format descriptors for SI
>> signalling
>>
>> If the insertion is not mandatory, one cannot rely upon its presence.
>> If not present, how is a conflict with another private use that has a
>> structure that is close to ULE prevented/resolved.
>>
>> Recommend RTR: " Transport Streams that utilise the Programme Map Table
>> (PMT)
>> defined in ISO 13818-1 [ISO-MPEG2] and that use the ULE
>> format defined in this document, SHALL insert a descriptor with
>> this value in the PMT ES_info descriptor loop."
>> __________________
>> Art Allison
>> Director, Advanced Engineering
>> NAB Science & Technology
>> 1771 N St NW, Washington DC 20036
>> 202 429 5418
>> -----Original Message-----
>> From: owner-ipdvb@erg.abdn.ac.uk [mailto:owner-ipdvb@erg.abdn.ac.uk]
>> Sent: Wednesday, July 27, 2005 2:47 PM
>> To: ipdvb@erg.abdn.ac.uk
>> Subject: Re: Proposed Changes to ULE text - Format descriptors for SI
>> signalling
>>
>>
>> After receiving a few suggestions, I now propose better text for the
>> description of the format identifier:
>>
>> Page 3, Section 1 (Introduction):
>> AFTER:
>> "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)."
>> ^ INSERT BLANK
>> LINE AND NEW PARAGRAPH after the above:
>> "A format_identifier value has been registered for ULE [ULE1].
>> This 32 bit number has a hexadecimal value of 0x554C4531.
>> Transport Streams that utilise the Programme Map Table (PMT)
>> defined in ISO 13818-1 [ISO-MPEG2] and that use the ULE
>> format defined in this document, SHOULD insert a descriptor with
>> this value in the PMT ES_info descriptor loop."
>>
>> Best wishes,
>>
>> Gorry
>>
>> Gorry Fairhurst wrote:
>>
>>>
>>> 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
>>>
>>> -----
>>> 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.
>>>
>>> -----
>>> 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?
>>>
>>> -----
>>> 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?
>>>
>>>
>>>
>
>