Subject: [AVT] Comments on draft-ietf-avt-rfc2429bis-00.txt

From: Magnus Westerlund <[email-masked]>
Date: Fri, 30 Jan 2004 15:54:52 +0100

Hi

Here is my comments on the update of RFC 2429. A lot of comments are 
similar to the ones for draft-ietf-avt-rfc2032-bis-00.txt.

1. Please try to submit documents with correct document dates, this says 
november.

2. In section 1, declare the intentions that this will update RFC 2429.

3. Conventions used in this document is missing. RFC 2119 pointer, and 
probably some other things should be here.

4. Section 2: fifth paragraph: Here I think one today should put in 
pointers at RTCP feedback.

5. Please work through and upgrade where appropriate to normative language.

6. Section 3: There should somewhere in the format specification be a 
note about that the usage of the timestamp make the RTCP jitter 
calculation to be less useful as it introduces jitter before transmission.

7. Section 3. Payload type: Please update the text with reference to 
profiles and usage of dynamic payload types.

8. Section 5.1: Reserved bits: I think it is appropriate to add: "MUST 
be ignored by receivers."

9. Section 5.1: PLEN: "If PLEN>0, the extra picture header
   is attached immediately following the rest of the payload header."
I don't think it is clear enough what attached immediately following the 
rest of payload header. Is this before or after the other video 
redundancy coding header extension?

10. Section 6.1: What is the start code bit order?

11. Section 8.1, This registration updates the previous registered 
version in RFC 3555. please spell this out.

12. Section 8: Again the space separated list needs to be replace with 
semicolon separated.

13. Section 8.1: all parameters needs values, and default 
interpretations. Some parameters could be changed into values for a new 
aggregating parameter.

14. There is need for RFC editor consideration.

15. Section 8.1.1: In the Author/Change controller a stray ">"

16. Section 8.1.1: PAR: It does not define how the values are separated, 
colon maybe.

17. Section 8.1.2: I don't know if you can make a parameter registration 
though reference.

18. Section 8.2.1: Please change the title of  "... options with SIP" to 
Offer/Answer.

19. Section 8.2.1: The order of the pictures size is not defined within 
the MIME parameter space at all. I think it belongs there if it is needed.

20. Section 8.2.1: The example using picture sizes: The definition of 
custom does not declare that space is allowed in the comma separated list.

21. Section 8.2.1: MaxBR and BPP: "MaxBitRate is video
   decoder property, hence it differs from SDP b : bandwidth-value
   attribute which refers more to application's total bandwidth (an
   application consists often of both audio and video)."

What the b= SDP parameter refers to depends on the modifier, CT, AS, RS, 
RR. So I think you need to be a bit more specific here.

22. Section 9. I thought that most video codecs contains some 
non-uniform processing depending on input. Is this not at least a small 
threat of DOS.

23. Section 9: I am missing the following topics: Integrity, and 
Authentication. Congestion control on best effort networks is also a 
consideration as the codec can after all produce a rather high bandwidth.

24. Section 11, belongs in the conventions section in the beginning.

25. Should RFC 2190 be declared historic?

26. What MIME type should be recommended to support in this new version.

27. What is the interoperability status on all parts of this specification?

28. The new parameters and possibly some other changes needs 
interoperability statements.

29. Section 12: The numbering of the changes are strange.

30. Please get the correct contact information for the previous authors. 
And contact them to in regards to there possible interaction with this 
specification in the future.

31. Please get correct page breaks.

Cheers

Magnus Westerlund 

Multimedia Technologies, Ericsson Research EAB/TVA/A
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