RTP Payload Format Restrictions
draft-ietf-mmusic-rid-15

[Ballot comment]
Presumably I'm just being dense, but from perusing the formal grammar
I couldn't decide if it's allowed to have both PT and parameter
restrictions applied on the same rid-id.


Section 5

Similarly (me being dense), I'm a bit confused at the relationship between max-fps and max-pps
-- aren't there encodings that can send update frames that do not include the full pixel density of a frame?


Section 6.2.2

  4.  If the "direction" field is "recv", The answerer ensures that
      "a=rid" restrictions are supported.  In the case of an
      unsupported restriction, the "a=rid" line is discarded.

"that "a=rid" restrictions are supported" reads like a feature test
for being able to parse a=rid at all, but the context suggests that
this is intended to refer to the Section-5 restriction stanzas that
appear on an a=rid line.


Section 8

I thought I remembered something going by to the effect of s/non-empty union/non-empty intersection/
but didn't find it in a quick search, so dropping a note just in case.

Section 8.2

  The following codec format parameters correspond to restrictions on
  receiver capabilities, and never indicate sending restrictions.

Maybe "The codec format parameters covered in the following
subsections [...]"?


Section 10

Should
    float-param-val  = 1*DIGIT "." 1*DIGIT
have the last entry be 1*4DIGIT to catch the "four digits after the
decimal place" requirement of max-bpp, or are we leaving the float-param-value
grammar less restricted in case of potential future use?

[Ballot comment]
(Meta-comment - thanks for helping me understand what's going on in Section 8, when discussing my previous Discuss)

If "rid" actually means something, it might be nice to expand it in the Abstract and Introduction. After the first couple of pages, I was guessing that it means something like "RTP Stream Identifier", based on a quick scan of https://tools.ietf.org/html/draft-ietf-avtext-rid-09, but that draft doesn't ever expand "rid" or use "rid" in the text, so then I think I'm wrong, because this draft also uses "rid-id", and I'm guessing that's probably not "RTP Stream Identifier Identifier". By the time I get down to Section 5, I decide it means "Restriction Identifier", but then I'm not any happier that I'm guessing "rid-id" means "Restriction Identifier Identifier" :-)

I'm confused by the SHOULD NOT in

  o  max-fps, for frame rate in frames per second.  For encoders that
      do not use a fixed framerate for encoding, this value should
      restrict the minimum amount of time between frames: the time
      between any two consecutive frames SHOULD NOT be less than 1/max-
      fps seconds.

The related description of max-pps, also uses a SHOULD, but explains why excursions outside this value are permissible.

(I'm also confused by "this value should restrict the minimum amount of time between frames" - I saw that you're using RFC 8174 for keywords, but is this just saying "this value restricts the minimum amount of time between frames", or something else?)

I note that 8.1 and 8.2 both include something like

  Both
  correspond to restrictions on receiver capabilities, and never
  indicate sending restrictions.

Is that true for all format parameters, for all codecs? If so, perhaps that should be explicit, in one of the normative sections (in which case, it wouldn't be useful here). If not, are implementations supposed to know what to do?

[Ballot comment]
Rich version of this review at:
https://mozphab-ietf.devsvcdev.mozaws.net/D3309


It took me a while to figure out how this works. I think I would
instead say something like "This document makes it possible to specify
multiple media profiles in a given session, e.g., for different
sending rates for simulcast. Each profile is associated with one or
more payload type and identified by a rid value which is carried in
the RTP payload [REF], thus allowing the receiver to demultiplex
different profiles (and hence sending streams within the session)"




COMMENTS
>      payload format and the associated SDP media description.  The SDP
>      rtpmap and/or fmtp attributes are used, for a given PT, to describe
>      the properties of the media that is carried in the RTP payload.
> 
>      Recent advances in standards have given rise to rich multimedia
>      applications requiring support for multiple RTP Streams within a RTP

Nit; "an RTP"


>      To expand on these points: [RFC3550] assigns 7 bits for the PT in the
>      RTP header.  However, the assignment of static mapping of RTP payload
>      type numbers to payload formats and multiplexing of RTP with other
>      protocols (such as RTCP) could result in a limited number of payload
>      type numbers available for application usage.  In scenarios where the
>      number of possible RTP payload configurations exceed the available PT

Nit: exceeds


>      a=rid:  [pt=;]=...
> 
>      An "a=rid" SDP media attribute specifies restrictions defining a
>      unique RTP payload configuration identified via the "rid-id" field.
>      This value binds the restriction to the RTP Stream identified by its
>      RTP Stream Identifier SDES item [I-D.ietf-avtext-rid].  To be clear,

SDES is kind of an overloaded term at this point.


>      the RtpStreamId SDES item described in [I-D.ietf-avtext-rid].  Such
>      implementations MUST send it for all streams in an SDP media
>      description ("m=") that have "a=rid" lines remaining after applying
>      the rules in Section 6 and its subsections.
> 
>      Implementations that use the "a=rid" parameter in SDP and that make

This is pretty hard to follow. Let me see if I understand this.  You
have a bunch of PTs and then each RID further restricts the parameters
for the set of PTs that it applies to?


>      media section ("m-line"); they do not necessarily need to be unique
>      within an entire RTP session.  In traditional usage, each media
>      section is sent on its own unique 5-tuple, which provides an
>      unambiguous scope.  Similarly, when using BUNDLE
>      [I-D.ietf-mmusic-sdp-bundle-negotiation], MID values associate RTP
>      streams uniquely to a single media description.

So you send both MID and RID in this case? That doesn't seem ideal,
but perhaps it should be stated.


> 
>      1.  The answerer ensures that the "a=rid" line is syntactically well
>          formed.  In the case of a syntax error, the "a=rid" line is
>          discarded.
> 
>      2.  Extract the rid-id from the "a=rid" line and verify its

This is in the imperative mode whereas the other steps are
descriptive. You probably want them to match


>      1.  The value of the "direction" field is reversed: "send" is changed
>          to "recv", and "recv" is changed to "send".
> 
>      2.  The answerer MAY choose to modify specific "a=rid" restriction
>          values in the answer SDP.  In such a case, the modified value
>          MUST be more restricted than the ones specified in the offer.

restrictive?


>          the offer, then the offerer SHALL discard the "a=rid" line.
> 
>      3.  If the restrictions have been changed between the offer and the
>          answer, the offerer MUST ensure that the modifications can be
>          supported; if they cannot, the offerer SHALL discard the "a=rid"
>          line.

Should you be checking for "more restricted"


>          comparison necessarily requires an understanding of the meaning
>          of codec parameters, rather than a rote byte-wise comparison of
>          their values.
> 
>      6.  If the "a=rid" line contains a "pt=", the offerer verifies that
>          the attribute values provided in the "a=rid" attributes are

Why did you break this out. It seems to just be an addition (5)

[Ballot discuss]
Please consider this to be an opportunity to explain something to an AD who doesn't understand codecs super well ... so I doubt it will be hard to clear my Discuss.

I'm not entirely comfortable that Section 8 isn't normative. Is the theory that if (for example) I decide that my H.264 format parameter maps onto a codec-independent parameter that you don't think it maps to, then you and I probably would probably end up ignoring the rid and doing what we would do, if one of us didn't support rids? If not, what's supposed to happen (normatively)?

[Ballot comment]
If "rid" actually means something, it might be nice to expand it in the Abstract and Introduction. After the first couple of pages, I was guessing that it means something like "RTP Stream Identifier", based on a quick scan of https://tools.ietf.org/html/draft-ietf-avtext-rid-09, but that draft doesn't ever expand "rid" or use "rid" in the text, so then I think I'm wrong, because this draft also uses "rid-id", and I'm guessing that's probably not "RTP Stream Identifier Identifier". By the time I get down to Section 5, I decide it means "Restriction Identifier", but then I'm not any happier that I'm guessing "rid-id" means "Restriction Identifier Identifier" :-)

I'm confused by the SHOULD NOT in

  o  max-fps, for frame rate in frames per second.  For encoders that
      do not use a fixed framerate for encoding, this value should
      restrict the minimum amount of time between frames: the time
      between any two consecutive frames SHOULD NOT be less than 1/max-
      fps seconds.

The related description of max-pps, also uses a SHOULD, but explains why excursions outside this value are permissible.

(I'm also confused by "this value should restrict the minimum amount of time between frames" - I saw that you're using RFC 8174 for keywords, but is this just saying "this value restricts the minimum amount of time between frames", or something else?)

I note that 8.1 and 8.2 both include something like

  Both
  correspond to restrictions on receiver capabilities, and never
  indicate sending restrictions.

Is that true for all format parameters, for all codecs? If so, perhaps that should be explicit, in one of the normative sections (in which case, it wouldn't be useful here). If not, are implementations supposed to know what to do?

[Ballot comment]
The document is generally fine, but I have a few minor comments:

In the ABNF:

  rid-width-param  = "max-width" [ "=" int-param-val ]

  rid-height-param  = "max-height" [ "=" int-param-val ]

  rid-fps-param    = "max-fps" [ "=" int-param-val ]

  rid-fs-param      = "max-fs" [ "=" int-param-val ]

  rid-br-param      = "max-br" [ "=" int-param-val ]

  rid-pps-param    = "max-pps" [ "=" int-param-val ]

  rid-bpp-param    = "max-bpp" [ "=" float-param-val ]


Maybe I missed that, but what is the meaning of "max-width" (and others) with no value?
Or to rephrase that: are the values really optional?


12.2.  Registry for RID-Level Parameters

  New restriction registrations are accepted according to the
  "Specification Required" policy of [RFC5226], provided that the
  specification includes the following information:

  o  contact name, email address, and telephone number

Considering the European GDPR directive is going to come into force in May: is there any legitimate use for collecting phone numbers for this registry?

  o  restriction name (as it will appear in SDP)

  o  long-form restriction name in English

  o  whether the restriction value is subject to the charset attribute

  o  an explanation of the purpose of the restriction

  o  a specification of appropriate attribute values for this
      restriction

  o  an ABNF definition of the restriction

  The initial set of "a=rid" restriction names, with definitions in
  Section 5 of this document, is given below:

    RID Parameter Name          Reference
    ------------------          ---------
    max-width                    [RFCXXXX]
    max-height                  [RFCXXXX]
    max-fps                      [RFCXXXX]
    max-fs                      [RFCXXXX]
    max-br                      [RFCXXXX]
    max-pps                      [RFCXXXX]
    max-bpp                      [RFCXXXX]
    depend                      [RFCXXXX]

And now you just registered them without following your registration template that you've specified above ;-).

[Ballot comment]
Rich version of this review at:
https://mozphab-ietf.devsvcdev.mozaws.net/D3309


It took me a while to figure out how this works. I think I would
instead say something like "This document makes it possible to specify
multiple media profiles in a given session, e.g., for different
sending rates for simulcast. Each profile is associated with one or
more payload type and identified by a rid value which is carried in
the RTP payload [REF], thus allowing the receiver to demultiplex
different profiles (and hence sending streams within the session)"




COMMENTS
>      payload format and the associated SDP media description.  The SDP
>      rtpmap and/or fmtp attributes are used, for a given PT, to describe
>      the properties of the media that is carried in the RTP payload.
> 
>      Recent advances in standards have given rise to rich multimedia
>      applications requiring support for multiple RTP Streams within a RTP

Nit; "an RTP"


>      To expand on these points: [RFC3550] assigns 7 bits for the PT in the
>      RTP header.  However, the assignment of static mapping of RTP payload
>      type numbers to payload formats and multiplexing of RTP with other
>      protocols (such as RTCP) could result in a limited number of payload
>      type numbers available for application usage.  In scenarios where the
>      number of possible RTP payload configurations exceed the available PT

Nit: exceeds


>      a=rid:  [pt=;]=...
> 
>      An "a=rid" SDP media attribute specifies restrictions defining a
>      unique RTP payload configuration identified via the "rid-id" field.
>      This value binds the restriction to the RTP Stream identified by its
>      RTP Stream Identifier SDES item [I-D.ietf-avtext-rid].  To be clear,

SDES is kind of an overloaded term at this point.


>      the RtpStreamId SDES item described in [I-D.ietf-avtext-rid].  Such
>      implementations MUST send it for all streams in an SDP media
>      description ("m=") that have "a=rid" lines remaining after applying
>      the rules in Section 6 and its subsections.
> 
>      Implementations that use the "a=rid" parameter in SDP and that make

This is pretty hard to follow. Let me see if I understand this.  You
have a bunch of PTs and then each RID further restricts the parameters
for the set of PTs that it applies to?


>      media section ("m-line"); they do not necessarily need to be unique
>      within an entire RTP session.  In traditional usage, each media
>      section is sent on its own unique 5-tuple, which provides an
>      unambiguous scope.  Similarly, when using BUNDLE
>      [I-D.ietf-mmusic-sdp-bundle-negotiation], MID values associate RTP
>      streams uniquely to a single media description.

So you send both MID and RID in this case? That doesn't seem ideal,
but perhaps it should be stated.


> 
>      1.  The answerer ensures that the "a=rid" line is syntactically well
>          formed.  In the case of a syntax error, the "a=rid" line is
>          discarded.
> 
>      2.  Extract the rid-id from the "a=rid" line and verify its

This is in the imperative mode whereas the other steps are
descriptive. You probably want them to match


>      1.  The value of the "direction" field is reversed: "send" is changed
>          to "recv", and "recv" is changed to "send".
> 
>      2.  The answerer MAY choose to modify specific "a=rid" restriction
>          values in the answer SDP.  In such a case, the modified value
>          MUST be more restricted than the ones specified in the offer.

restrictive?


>          the offer, then the offerer SHALL discard the "a=rid" line.
> 
>      3.  If the restrictions have been changed between the offer and the
>          answer, the offerer MUST ensure that the modifications can be
>          supported; if they cannot, the offerer SHALL discard the "a=rid"
>          line.

Should you be checking for "more restricted"


>          comparison necessarily requires an understanding of the meaning
>          of codec parameters, rather than a rote byte-wise comparison of
>          their values.
> 
>      6.  If the "a=rid" line contains a "pt=", the offerer verifies that
>          the attribute values provided in the "a=rid" attributes are

Why did you break this out. It seems to just be an addition (5)

The following Last Call announcement was sent out (ends 2018-03-30):

From: The IESG
To: IETF-Announce
CC: ben@nostrum.com, mmusic@ietf.org, mmusic-chairs@ietf.org, Flemming Andreasen , fandreas@cisco.com, draft-ietf-mmusic-rid@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: EXTENDED Last Call:  (RTP Payload Format Restrictions) to Proposed Standard


The IESG has received a request from the Multiparty Multimedia Session
Control WG (mmusic) to consider the following document: - 'RTP Payload Format
Restrictions'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2018-03-30. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.

Abstract


  In this specification, we define a framework for specifying
  restrictions on RTP streams in the Session Description Protocol.
  This framework defines a new "rid" SDP attribute to unambiguously
  identify the RTP Streams within a RTP Session and restrict the
  streams' payload format parameters in a codec-agnostic way beyond
  what is provided with the regular Payload Types.

  This specification updates RFC4855 to give additional guidance on
  choice of Format Parameter (fmtp) names, and on their relation to the
  restrictions defined by this document.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-rid/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-rid/ballot/


No IPR declarations have been submitted directly on this I-D.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Services Operator has completed its review of draft-ietf-mmusic-rid-13. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there are two actions which we must complete. We have a question about one of the actions.

First, in the att-field (media level only) registry on the Session Description Protocol (SDP) Parameters registry page located at:

https://www.iana.org/assignments/sdp-parameters/

a single new registration will be made as follows:

Type: att-field (media level only)
SDP Name: rid
Mux Category: SPECIAL
Reference: [ RFC-to-be ]

As this document requests registration in an Expert Review (see RFC 8126) registry, we have initiated the required expert review via a separate request. Expert review should be completed before your document is approved for publication as an RFC.

Second, a new registry is to be created called the att-field (rid level) registry. The new registry will be located on the Session Description Protocol (SDP) Parameters registry page located at:

https://www.iana.org/assignments/sdp-parameters/

The new registry is to be managed via Specification Required, as defined in RFC 8126.

IANA Question --> Should this registry include the "Mux Category" field that appears in other att-field registries?

There are initial registrations in the new registry:

Type SDP Name Reference
---------------------+-----------+--------------
att-field (rid level)
att-field (rid level) max-width [ RFC-to-be ]
att-field (rid level) max-height [ RFC-to-be ]
att-field (rid level) max-fps [ RFC-to-be ]
att-field (rid level) max-fs [ RFC-to-be ]
att-field (rid level) max-br [ RFC-to-be ]
att-field (rid level) max-pps [ RFC-to-be ]
att-field (rid level) max-bpp [ RFC-to-be ]
att-field (rid level) depend [ RFC-to-be ]

The IANA Services Operator understands that these are the only actions required upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

Thank you,

Amanda Baber
Lead IANA Services Specialist

The following Last Call announcement was sent out (ends 2018-03-06):

From: The IESG
To: IETF-Announce
CC: ben@nostrum.com, mmusic@ietf.org, mmusic-chairs@ietf.org, Flemming Andreasen , fandreas@cisco.com, draft-ietf-mmusic-rid@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (RTP Payload Format Restrictions) to Proposed Standard


The IESG has received a request from the Multiparty Multimedia Session
Control WG (mmusic) to consider the following document: - 'RTP Payload Format
Restrictions'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2018-03-06. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.

Abstract


  In this specification, we define a framework for specifying
  restrictions on RTP streams in the Session Description Protocol.
  This framework defines a new "rid" SDP attribute to unambiguously
  identify the RTP Streams within a RTP Session and restrict the
  streams' payload format parameters in a codec-agnostic way beyond
  what is provided with the regular Payload Types.

  This specification updates RFC4855 to give additional guidance on
  choice of Format Parameter (fmtp) names, and on their relation to the
  restrictions defined by this document.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-rid/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-mmusic-rid/ballot/


No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Proposed Standard. The title page shows the Intended status as Standards Track, which is appropriate given that the document updates RFC 4855

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  Relevant content can frequently be found in the abstract
  and/or introduction of the document. If not, this may be
  an indication that there are deficiencies in the abstract
  or introduction.

In this specification, we define a framework for specifying restrictions on RTP streams in the Session Description Protocol. This framework defines a new "rid" SDP attribute to unambiguously identify the RTP Streams within a RTP Session and restrict the streams' payload format parameters in a codec-agnostic way beyond what is provided with the regular Payload Types.

This specification updates RFC4855 to give additional guidance on choice of Format Parameter (fmtp) names, and on their relation to the restrictions defined by this document.

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly
  rough?

No issues to note.

Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

There are currently no known implementations of the protocol, however the document is a normative dependency for the W3C WebRTC specification.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Flemming Andreasen is the Document Shepherd
Ben Campbell is the Responsible Area Direction

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

I have reviewed -08 of the draft in detail, which resulted in a few updates. I have reviewed the subsequent changes as well. 


(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No concern. Several people have reviewed slightly earlier versions of the document which are substantially similar to the current document. The recent changes (up to -12) have been discussed on the WG list and in meetings as well. Discussions on a related draft in the most recent IETF meeting (Singapore, 100) recently led to a few minor updates related to RTP Stream Redundancy and RTP Redundancy Payload Format. The resulting update was announced on the MMUSIC mailing list with no further comments received.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

N/A

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

The author has confirmed.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

N/A

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

There is solid consensus in the WG with several people having both participated and reviewed the document.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

N/A

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

No nits found.
The idnits tool does produce a couple of warnings, however none of them apply except for one: The reference to RFC 5226 should be replaced with a reference to RFC 8126, which can be done during the publication process.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

Yes. The document normatively references draft-ietf-avtext-rid-09 which is currently with RFC Editor (in MISSREF state).


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

N/A

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No status change, however the document does update RFC 4855, which is called out on in the title page header and abstract. The document discusses the updated mechanism in the Introduction but does not specifically call out RFC 4855.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The document defines a new SDP attribute which has a proper IANA registration (per RFC 4566) in the IANA Considerations section

The document also defines a new IANA registry within the SDP parameters registry. This new registry is well defined incl initial values and a "Specification Required" policy for the registry. Adam Roach (adam@nostrum.com) has volunteered to be Designated Expert for the registry.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

See above.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

ABNF has been verified with Bill Fenner's ABNF parser.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Proposed Standard. The title page shows the Intended status as Standards Track, which is appropriate given that the document updates RFC 4855

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  Relevant content can frequently be found in the abstract
  and/or introduction of the document. If not, this may be
  an indication that there are deficiencies in the abstract
  or introduction.

In this specification, we define a framework for specifying restrictions on RTP streams in the Session Description Protocol. This framework defines a new "rid" SDP attribute to unambiguously identify the RTP Streams within a RTP Session and restrict the streams' payload format parameters in a codec-agnostic way beyond what is provided with the regular Payload Types.

This specification updates RFC4855 to give additional guidance on choice of Format Parameter (fmtp) names, and on their relation to the restrictions defined by this document.

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly
  rough?

No issues to note.

Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

There are currently no known implementations of the protocol, however the document is a normative dependency for the W3C WebRTC specification.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Flemming Andreasen is the Document Shepherd
Ben Campbell is the Responsible Area Direction

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

I have reviewed -08 of the draft in detail, which resulted in a few updates. I have reviewed the subsequent changes as well. 


(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No concern. Several people have reviewed slightly earlier versions of the document which are substantially similar to the current document. The recent changes (up to -12) have been discussed on the WG list and in meetings as well. Discussions on a related draft in the most recent IETF meeting (Singapore, 100) recently led to a few minor updates related to RTP Stream Redundancy and RTP Redundancy Payload Format. The resulting update was announced on the MMUSIC mailing list with no further comments received.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

N/A

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

The author has confirmed.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

N/A

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

There is solid consensus in the WG with several people having both participated and reviewed the document.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

N/A

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

No nits found.
The idnits tool does produce a couple of warnings, however none of them apply except for one: The reference to RFC 5226 should be replaced with a reference to RFC 8126, which can be done during the publication process.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

Yes. The document normatively references draft-ietf-avtext-rid-09 which is currently with RFC Editor (in MISSREF state).


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

N/A

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No status change, however the document does update RFC 4855, which is called out on in the title page header and abstract. The document discusses the updated mechanism in the Introduction but does not specifically call out RFC 4855.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The document defines a new SDP attribute which has a proper IANA registration (per RFC 4566) in the IANA Considerations section

The document also defines a new IANA registry within the SDP parameters registry. This new registry is well defined incl initial values and a "Specification Required" policy for the registry. Adam Roach (adam@nostrum.com) has volunteered to be Designated Expert for the registry.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

See above.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

ABNF has been verified with Bill Fenner's ABNF parser.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Proposed Standard. The title page shows the Intended status as Standards Track, which is appropriate given that the document updates RFC 4855

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

  Relevant content can frequently be found in the abstract
  and/or introduction of the document. If not, this may be
  an indication that there are deficiencies in the abstract
  or introduction.

In this specification, we define a framework for specifying restrictions on RTP streams in the Session Description Protocol. This framework defines a new "rid" SDP attribute to unambiguously identify the RTP Streams within a RTP Session and restrict the streams' payload format parameters in a codec-agnostic way beyond what is provided with the regular Payload Types.

This specification updates RFC4855 to give additional guidance on choice of Format Parameter (fmtp) names, and on their relation to the restrictions defined by this document.

Working Group Summary

  Was there anything in WG process that is worth noting? For
  example, was there controversy about particular points or
  were there decisions where the consensus was particularly
  rough?

No issues to note.

Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

There are currently no known implementations of the protocol, however the document is a normative dependency for the W3C WebRTC specification.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Flemming Andreasen is the Document Shepherd
Ben Campbell is the Responsible Area Direction

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

I have reviewed -08 of the draft in detail, which resulted in a few updates. I have reviewed the subsequent changes as well.


(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No concern. Several people have reviewed slightly earlier versions of the document which are substantially similar to the current document. The recent changes have been discussed on the WG list and in meetings as well.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

N/A

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

The author has confirmed.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

N/A

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

There is solid consensus in the WG with several people having both participated and reviewed the document.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

N/A

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

No nits found.
The idnits tool does produce a couple of warnings, however none of them apply except for one: The reference to RFC 5226 should be replaced with a reference to RFC 8126, which can be done during the publication process.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

Yes. The document normatively references draft-ietf-avtext-rid-09 which is currently with RFC Editor (in MISSREF state).


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

N/A

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No status change, however the document does update RFC 4855, which is called out on in the title page header and abstract. The document discusses the updated mechanism in the Introduction but does not specifically call out RFC 4855.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

The document defines a new SDP attribute which has a proper IANA registration (per RFC 4566) in the IANA Considerations section

The document also defines a new IANA registry within the SDP parameters registry. This new registry is well defined incl initial values and a "Specification Required" policy for the registry. Adam Roach (adam@nostrum.com) has volunteered to be Designated Expert for the registry.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

See above.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

ABNF has been verified with Bill Fenner's ABNF parser.

Request for posting confirmation emailed to previous authors: mmusic-chairs@ietf.org, Adam Roach , Bo Burman , Mo Zanaty , Suhas Nandakumar , Byron Campen , Peter Thatcher