Shepherd writeup
rfc8251-10

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. This is the proper type of RFC, since this is an update to RFC 6716, which is also Standards Track. The title page header indicates that the intended status of this draft is Standards Track.

(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.

This document addresses minor issues that were found in the specification of the Opus audio codec in RFC 6716. This is primarily done via a series of small bug fixes to the normative code published with the original RFC.

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?

Jonathan Rosenberg, then WG chair, originally stated that updates to RFC 6716 would be handled via the normal errata process. However, after conferring with our ADs, he and I decided that handling these via a new draft would avoid any questions about overriding WG consensus. That decision was announced by me in 2013 with the first version of the draft, Jonathan Rosenberg voiced his approval of it on the list afterwards, and no one has raised an issue with it since then.

We have held the document open for some time to give people a chance to find new issues, but the rate of new reports has dropped off, and the last issue was reported in October. Thus there is likely not much value in further postponing publication.

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?

The updates have been implemented in libopus 1.2, released on 20 June 2017. They were available in pre-release versions for testing purposes for nearly a year prior (several years, for some of the changes). Currently they require a special option to enable them at configuration time. The authors expect to remove that option (enabling the updates by default) in a new version of libopus once this document is published as an RFC. Most users of libopus, which includes all of the major browsers, Android, iOS, and many others, will then get the new behavior once they upgrade. The authors of the Opus decoder in FFmpeg, another open source implementation, have also stated their intention to implement the updates in this draft.

Mark Harris, Tina le Grand, and Jonathan Lennox all performed detailed reviews. Mark Harris is a long time contributor to the libopus open source project, with a deep familiarity with the codebase and a long track record of finding bugs and issues with new changes to it. Tina le Grand is the primary developer responsible for Opus's integration into WebRTC for Chrome, and Jonathan Lennox is the primary developer responsible for Opus's integration into Vidyo's products. Both have a number of contributions to the open source project and are familiar with the design and implementation of Opus. All three had a number of editorial suggestions, but identified no major issues with any of the proposed fixes. Additional review was performed by Ralph Giles, Michael Graczyk, Ron Lee, Felicia Lim, Gregory Maxwell, and Jan Skoglund.

Personnel

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

  Document Shepherd: Timothy B. Terriberry
  Responsible Area Director: Ben Campbell

(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 reviewed all of the fixes before the first publication of the draft, and personally performed some of the analysis that led to a few of those fixes. I have also reviewed the fixes that were added since the first version in some detail. As an author of the original RFC 6716 and a developer of the libopus open-source project, I believe that all of them are technically correct and warranted, and that they will not cause compatibility issues with implementations of the original RFC 6716. I believe this document adequately describes the fixes, and that it is ready for publication.

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

No.

(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.

The document has no AAA, DNS, DHCP, XML, or internationalization components, and I believe that it raises no new security or operational complexity issues beyond that of RFC 6716. Therefore we have not sought such review.

(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.

I have no specific concerns or issues.

(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.

Yes.

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

No IPR disclosures have been filed that reference this document.

(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?   

I believe that the members of the WG who remained active after the completion of the original RFC 6716 (which is understandably a smaller number than were involved in RFC 6716 itself) as a whole understand and agree with this 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.) 

No appeals or other indications of extreme discontent have been threatened or lodged.

(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 ID nits were identified.

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

This document does not define a new MIB, media type, or URI type.

(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?

No.

(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. 

No.

(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.

This document updates RFC 6716. RFC 6716 is listed on the title page header, in the abstract, and is discussed in the introduction.

(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).

This document does not define any new protocol extensions, reference any IANA registries, or create any new IANA registries.

(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.

N/A

(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.

I have checked that the C code patches included in the document match those in the linked machine-readable version, apply cleanly to the code published with RFC 6716, compile, and function as expected. The decoder successfully decodes all of the updated test vectors with an average mono quality of 97.425% and an average stereo quality of 99.7333% on my machine.
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