[AVT] RE: Comments on draft-ietf-avt-rfc2032-bis-11
"Even, Roni" <roni.even@polycom.co.il> Tue, 17 January 2006 09:17 UTC
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Date: Tue, 17 Jan 2006 11:17:27 +0200
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From: "Even, Roni" <roni.even@polycom.co.il>
To: Magnus Westerlund <magnus.westerlund@ericsson.com>, IETF AVT WG <avt@ietf.org>
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Subject: [AVT] RE: Comments on draft-ietf-avt-rfc2032-bis-11
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Hi Magnus, Thanks, see my response inline Roni -----Original Message----- From: Magnus Westerlund [mailto:magnus.westerlund@ericsson.com] Sent: Wednesday, January 11, 2006 4:24 PM To: Even, Roni; IETF AVT WG Subject: Comments on draft-ietf-avt-rfc2032-bis-11 Hi, I have reviewed the draft and have some nits. Yes we are mostly talking nits but fixing them will make publication process go smoother. 1. Front page:Paragraph starting with: This specification is a product of ... Please move that to the status of this memo section. I don't think the idnits tool complains about this. RE: The status of this memo section is added by the xml2rfc schema, but I think it is right to remove the second paragraph in the abstract section 2. The abstract. It is to short. A single sentence abstract is not acceptable and will be commented on. So please expand it a bit. Please remember From the online ID checklist: http://www.ietf.org/ID-Checklist.html#anchor6 # Abstract A Should be meaningful to someone not versed in the technology; most abbreviations must be expanded on first use B no citations C See [I-D.rfc-editor-rfc2223bis] (Reynolds, J. and R. Braden, "Instructions to Request for Comments (RFC) Authors," July 2004.) section 4.5. from draft-rfc-editor-rfc2223bis-08: 4.5 Abstract Every RFC must have an Abstract section following the Copyright notice. An Abstract will typically be 5-10 lines. An Abstract of more than 20 lines is generally not acceptable. The Abstract section should provide a concise and comprehensive overview of the purpose and contents of the entire document, to give a technically knowledgeable reader a general overview of the function of the document. In addition to its function in the RFC itself, the Abstract section text will appear in publication announcements and in the online index of RFCs. ... RE: OK 3. A general editorial thing is that the citations in this document are always directly following a word. Please insert a space before the [ref] bracket. RE:OK 4. Section 1. Last paragraph: " This document updates RFC 2032 and the "video/h261" media type that was registered in RFC 3555." Is that really the intention of the document. I thought it was to obsolete RFC 2032 and update the "video/h261" media type in RFC 3555? RE: I got this sentence from Collin but I think that your comment is more precise, so I will change the updates to obsolete. 5. Section 3.2, second paragraph: "Similarly, we will not attempt to multiplex audio and video signals in the same packets, as UDP and RTP provide a much more efficient way to achieve multiplexing." Wouldn't it be better to replace the word "efficient" with "suitable"? RE: OK 6. Section 4.1, high order bit number scale is out of alignment on both figures on page 8. RE: OK, Thanks 7. Section 5, last paragraph: "The first method is by using the Extended RTP Profile for RTCP-based Feedback and sending RTCP generic control packets as described in Even Expires July 8, 2006 [Page 11] Internet-Draft H.261 RTP payload format January 2006 draft-ietf-avt-rtcp-feedback[rtcp-feedback]." I think you should replace "draft-ietf-avt-rtcp-feedback" with "RFCXXXX" and an RFC editor note asking them to replace XXXX with the RFC number draft-ietf-avt-rtcp-feedback receives. RE: Is this a dependency for publication - I thought that it is OK to have such a reference in the informative section. 8. Section 6.1: I think this section should indicate that registration has been done using RFC 4288 template and the rules in RFC 3555. RE: I do not mind mentioning RFC4288 template but I fail to see the value. The registration updates the current registered version in RFC3555. So is it really required to add 4288 9. Section 6.1.1: D parameter: D: specifies support for still image graphics according to H.261 annex D. If supported SHALL have the value "1". If not supported SHOULD NOT be listed or SHALL have the value "0". I think the later two sentences could benefit from being written as real sentences. I would propose: D: specifies support for still image graphics according to H.261 annex D. If supported the parameter value SHALL be "1". If not supported the parameter SHOULD NOT be used or SHALL have the value "0". RE: OK 10. Section 6.2.1: "If the receiver does not specify the picture size /MPI optional parameter then it SHOULD be ready to receive QCIF resolution with MPI=1." I think using SHOULD here is a bit problematic. If this is not enforced, then what can you expect when a client answers without any parameters. And this is an issue of handling non updated terminals also. As I see there are a few alternatives that provide better solutions: A. Require all updated implementations to always indicate their receiver capabilities. Even if it is QCIF with MPI = 1. Then state that any counter part that not supported the updated spec will thus be detectable and it is recommended to use QCIF with MPI = 1 because it will most likely work. B. Require that anyone follows this specification SHALL support QCIF and MPI=1 if it doesn't include any parameter indicating otherwise. Then include a statement about backwards compatibility that it is likely that this work but not guaranteed. Or where there any other reason why there is a SHOULD in that sentence? RE: You got the right reason, the receiver can assume that it is most likely that he will get QCIF. As for the rephrasing I prefer option A which have the same meaning. Option B implies that a receiver must support QCIF, this will enable encoder to send QCIF even if it was not signaled. 11. Section 7.1: This new RFC suggest generic methods to address the same requirement. I think you should change "new RFC" to "memo" to more clearly indicate that it is this document that you refer to. "memo" seem to be a favorite word of the RFC editor. RE: OK 12. Section 7.1: Since these are optional features new implementations SHALL ignores them and they SHALL not be used by new implementations. Two things: "ignores" shouldn't this be "ignore"? And "not" after SHALL needs to be "NOT". RE: OK 13. Section 7.2, connect with my comments in issue 10. I think one can clear explain that we expect that any H261 implementation will support QCIF and 30 Hz. And that is what will happen when new peers connect to old ones, assuming that they ignore the parameters they do not understand. This is something I would not like to put all my money on. RE: I agree that almost any H.261 implementation may support QCIF 30 but I did not want to make this implicit since it will prevent a receiver that implement the new optional parameters from stating that he wants to receive CIF and not QCIF. 14. Section 8. I think the security section needs a bit of rewrite. The first part of paragraph 1 is fine. However the second one is not okay. We have received AD comments on the formulation about encryption and order. I would suggest that you change the paragraph to: RTP packets using the payload format defined in this specification are subject to the security considerations discussed in the RTP specification [RFC3550], and any appropriate RTP profile (for example [RFC3551]). This implies that confidentiality of the media streams is achieved by encryption. SRTP [RFC3711] may be used to provide both encryption and integrity protection of RTP flows. Then the second sentence is fine with the exception that is lacking an authorative statement if that is the case or not for the H261 codec. So please clarify if H261 exhibits any such behavior or not. I would remove the complete last paragraph. It statement is very generic however I don't think it present either a fair statement of the issue or provide any sufficient recommendations. Also this a generic problem that is not particular to RTP nor specifically to this payload format. RE: I will remove the last paragraph add your suggestion to the start and clarify that encryption will be done after the encoding " encryption will be performed after" 15. Section 11.2: The reference to rtcp-feedback. Is this not a normative reference? You recommend that one uses this format for NACK and loss indication. Also the version of that draft has been updated, it is now 11. RE: I see this as an example for a method and not the only method, this is why it is informative. 16. Super minor nit: Your draft includes the RFC editors standard acknowledgment about funding. However that has now changed due to new administrative structure of the IETF. For your information it now reads: Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). However I do assume that it is put there by XML2RFC. In that case ignore this comment. RE: I am using XML2RFC, at least I will verify I am using the latest version Cheers Magnus -- Magnus Westerlund Multimedia Technologies, Ericsson Research EAB/TVA/A ---------------------------------------------------------------------- Ericsson AB | Phone +46 8 4048287 Torshamsgatan 23 | Fax +46 8 7575550 S-164 80 Stockholm, Sweden | mailto: magnus.westerlund@ericsson.com _______________________________________________ Audio/Video Transport Working Group avt@ietf.org https://www1.ietf.org/mailman/listinfo/avt
- [AVT] Comments on draft-ietf-avt-rfc2032-bis-11 Magnus Westerlund
- [AVT] RE: Comments on draft-ietf-avt-rfc2032-bis-… Even, Roni
- [AVT] Re: Comments on draft-ietf-avt-rfc2032-bis-… Magnus Westerlund
- [AVT] RE: Comments on draft-ietf-avt-rfc2032-bis-… Even, Roni