Subject: [AVT] draft-ietf-avt-rtcp-non-compound-04

From: "Ingemar Johansson S" <[email-masked]>
Date: Fri, 25 Apr 2008 14:40:41 +0200

Hi

A new version of the Non-compound RTCP draft has been submitted. 
Read and enjoy. Comments are as always welcome.

Some comments from me:

+ Name: The present version has the term "Non-compound RTCP" defined, however, with the given defintion, the term may be misleading or confusing. I am not uncomfortable with the name but suggestions for a better name are welcome.

+ RTCP packet: I have throughout the draft had a hard time to figure out what is the correct RTCP*** to write here and there and I fear that the current draft is infested with ambiguities because of this.
 Examples:
  + SR or RR: Should I  write "RR packet" or "RR RTCP packet" or "RR item" ?
  + SDES : Should I call it "SDES CNAME item" or "SDES CNAME RTCP packet" or something else ?
  + Is it "Many RTCP packets in one RTCP packet" or 
         "Many RTCP packets in one lower layer datagram" ?
 I guess there are probably some good definitions hidden out there but even though I have read RFC3550/4585 a number of times I am still confused. Any help appreciated (I cannot promise a beer though).

Regards 
Ingemar
******************************************* 
Ingemar Johansson 
Senior Research Engineer, IETF "nethead" 
EAB/TVP - Multimedia Technologies 
Ericsson Research Ericsson AB 
Box 920 S-971 28 Luleå, Sweden 
Tel: +46 (0)8 4043042 
ECN: 850-43042 
ECC: 850-43074 
Mobile: +46 (0)730 783289 
******************************************* 
_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www.ietf.org/mailman/listinfo/avt

---

From: Randell Jesup <[email-masked]>
Date: Fri, 25 Apr 2008 09:56:12 -0400

"Ingemar Johansson S" <[email-masked]> writes:
>+ Name: The present version has the term "Non-compound RTCP" defined,
>  however, with the given defintion, the term may be misleading or
>  confusing. I am not uncomfortable with the name but suggestions for a
>  better name are welcome. 

Maybe "Reduced Size RTCP"?  That's really what we're doing here, and it
speaks to the motivation.

>+ RTCP packet: I have throughout the draft had a hard time to figure out
>  what is the correct RTCP*** to write here and there and I fear that the
>  current draft is infested with ambiguities because of this. 

This is a great big confusing mess.  The older RTP drafts did a horrible
disservice to everyone by calling the RTCP whatevers "packets".  I would
strongly prefer to call them "RTCP items" or "RTCP sub-packets" or "RTCP
units", and up-front in the draft describe what we mean by that.

> I guess there are probably some good definitions hidden out there but
> even though I have read RFC3550/4585 a number of times I am still
> confused. Any help appreciated (I cannot promise a beer though). 

-- 
Randell Jesup, Worldgate (developers of the Ojo videophone), ex-Amiga OS team
[email-masked]
"The fetters imposed on liberty at home have ever been forged out of the weapons
provided for defence against real, pretended, or imaginary dangers from abroad."
		- James Madison, 4th US president (1751-1836)

---

From: Colin Perkins <[email-masked]>
Date: Fri, 25 Apr 2008 17:35:40 +0100

Hi,

On 25 Apr 2008, at 13:40, Ingemar Johansson S wrote:
> + Name: The present version has the term "Non-compound RTCP"  
> defined, however, with the given defintion, the term may be  
> misleading or confusing. I am not uncomfortable with the name but  
> suggestions for a better name are welcome.

Using the term "non-compound RTCP" for anything other than a single  
RTCP Packet contradicts RFC 3550, so I don't think the definition in  
the draft works.

> + RTCP packet: I have throughout the draft had a hard time to  
> figure out what is the correct RTCP*** to write here and there and  
> I fear that the current draft is infested with ambiguities because  
> of this.

RFC 3550 consistently uses the terms "RTCP packet" and "compound RTCP  
packet". It states that "multiple RTCP packets are sent together as a  
compound RTCP packet in a single packet of the underlying protocol".  
I've never particularly liked these terms, but they're used  
consistently, and it's probably too late to change them.

>   + SR or RR: Should I  write "RR packet" or "RR RTCP packet" or  

Are you talking about the packet, or the information contained within  
it? An RTCP RR packet contains zero or more reception report blocks.

> packet" or something else ?

Again, it depends whether you're discussing the packet or its  
contents. An RTCP SDES packet contains zero or more chunks, and each  
chunk contains zero or more SDES items. You'd talk about a CNAME  
item, being contained within an RTCP SDES packet.

>          "Many RTCP packets in one lower layer datagram" ?

There are several RTCP packets in a compound RTCP packet. The  
compound RTCP packet is transmitted in one lower layer datagram.

Cheers,
Colin