Subject: [AVT] Inquiry about RFC 4629 (optional parameters in SDP)

From: Regis Crinon <[email-masked]>
Date: Mon, 3 Sep 2007 21:54:18 -0700

Hello everyone,

I have the following question regarding RFC 4629. I would really appreciate your feedback.
Thank you in advance,

Regis J. Crinon

Fact 1:

H.263+ includes a set of new Annexes: Annex I through T.

Fact 2:

RFC 4629 account for ONLY a subset of these annexes. See excerpts from the RFC below:

A list of optional annexes specifies which annexes of H.263 are
      supported.  The optional annexes are defined as part of H263-1998,
      H263-2000.  H.263 annex X [H263] defines profiles that group
      annexes for specific applications.  A system that supports a
      specific annex SHALL specify its support using the optional
      parameters.  If no annex is specified, then the stream is Baseline
      H.263.

      The allowed optional parameters for the annexes are "F", "I", "J",
      "T", "K", "N", and "P".

Question

How are the other annexes signaled? Example: How can I signal that an H.263+ bistream uses Annex L or Annex M or Annex O or Annex Q or Annex R or Annex S? It seems that I cannot use SDP to tell a video bitstream that uses one or more of these annexes from one that does not. Hence the question.

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: "Even, Roni" <[email-masked]>
Date: Tue, 4 Sep 2007 20:18:43 +0300

Hi,

The reason for this selection of annexes was based on the ones being
used by products in the markets.  There is no need to specify parameters
that are not used.

You can also use annex X based profiles for specifying other application
based profile.

Roni Even

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A consensus means that everyone agrees to say collectively what no one
believes individually
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 

________________________________

From: Regis Crinon [mailto:[email-masked]] 
Sent: Tuesday, September 04, 2007 7:54 AM
To: [email-masked]
Subject: [AVT] Inquiry about RFC 4629 (optional parameters in SDP)

Hello everyone,

I have the following question regarding RFC 4629. I would really
appreciate your feedback.

Thank you in advance,

Regis J. Crinon

Fact 1:

Fact 2:

RFC 4629 account for ONLY a subset of these annexes. See excerpts from
the RFC below:

      H.263.

      "T", "K", "N", and "P".

Question

How are the other annexes signaled? Example: How can I signal that an
H.263+ bistream uses Annex L or Annex M or Annex O or Annex Q or Annex R
or Annex S? It seems that I cannot use SDP to tell a video bitstream
that uses one or more of these annexes from one that does not. Hence the
question.

---

From: Randell Jesup <[email-masked]>
Date: Tue, 04 Sep 2007 13:36:53 -0400

>used by products in the markets.  There is no need to specify parameters

Ummm... that just seems totally confused to me.  We won't provide a way
to negotiate feature X because no one currently uses feature X - but if you
can't negotiate it, what use is it to implement it?  (Other than in a 
private, non-RFC-based, non-interoperable setup.)

It just asks people to either ignore the standard and go totally
proprietary, extend it ad-hoc and quite possibly incompatibly, or
cut off any work on using those annexes ever.

>You can also use annex X based profiles for specifying other application

Which is basically a private, incompatible negotiation.

I realize this is the way the RFC is; I'm just wondering as to why.  Maybe
the point was no one had implemented them and the WG believed no would
would implement them for good reason, and they were effectively deprecated.

-- 
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: "Even, Roni" <[email-masked]>
Date: Tue, 4 Sep 2007 20:49:57 +0300

Randell,
Those annexes can be signaled as part of profiles in annex X of H.263. 
Annex X is not proprietary; you can use H263-2000 with profile and
levels.
Specific bodies like 3GPP recommended specific annex X profiles.

There was no request to use them as separate annexes not part of
profiles.

I do not think that anyone will develop a new product using a specific
annex not in the list or not part of a profile. There is H.264 today.

In H.323 we had all the annexes with all the options.
Since in IETF for a standard you must have only parameters that are used
we asked on the list if people are using other annexes which were not in
RFC 4629.

Roni

> -----Original Message-----
> From: Randell Jesup [mailto:[email-masked]]
> Sent: Tuesday, September 04, 2007 8:37 PM
> To: Even, Roni
> Cc: Regis Crinon; [email-masked]
> Subject: Re: [AVT] Inquiry about RFC 4629 (optional parameters in SDP)
> 
> to negotiate feature X because no one currently uses feature X - but
if
> you
> 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."

---

From: Randell Jesup <[email-masked]>
Date: Wed, 05 Sep 2007 00:13:03 -0400

"Even, Roni" <[email-masked]> writes:
>Annex X is not proprietary; you can use H263-2000 with profile and levels.

Ah.  Ok, that makes more sense; when you said "profiles" I thought you
meant profiles in the SDP sense (like RTP/AVP).

>annex not in the list or not part of a profile. There is H.264 today.

True, though H.264 uses a lot more computational resources; *if* you have
the bits to throw at it, 263+ may let you get higher framerates or
resolutions than 264 on a given platform.

>we asked on the list if people are using other annexes which were not in

It probably doesn't matter, but I'm not clear about "for a standard you
must have only parameters that are used" and how exactly it applies here.
Most IETF standards predate their usage, so that doesn't make sense.

---

From: Carsten Bormann <[email-masked]>
Date: Wed, 5 Sep 2007 10:12:36 +0200

On Sep 05 2007, at 06:13, Randell Jesup wrote:

>  but I'm not clear about "for a standard you

I think the point is that 2429 (4629's predecessor) has been around  
for a while, and apparently there was no need for the other Annexes,  
at least as perceived by the WG.
4629 might actually even be the basis for going to Draft Standard,  
where there is indeed a requirement to only have options for which  
independent interoperable implementations can be demonstrated.

As a general observation about the grim reality, codec "standards"  
generally carry lots of baggage that is motivated by company X  
wanting to get their random patents in, too.  You don't really want  
to weigh down real-world standards by all that _a__age.  So, in a  
way, 2429/4629 are "profiling" H.263 for Internet work.

Gruesse, Carsten