Subject: RE: [AVT] I-D ACTION:draft-ietf-avt-rtp-ac3-02.txt

From: "Link, Brian" <[email-masked]>
Date: Tue, 1 Feb 2005 15:28:38 -0800

Hi,

As quoted below, I have submitted a revised version of the RTP payload
format for AC-3. I believe it addresses all the comments I received
about the last version, except one: I have left the SMPTE time stamps in
the payload specific header since they are optional. There has been some
discussion of finding a mechanism to generalize this capability for
other payload formats. I support that and also find value in keeping
this optional mechanism in place. When I proposed keeping it to the AVT
reflector, I heard no objections.

Please review this version of the document and offer any feedback you
have.

I've made these changes in the -02 version:
-Changed the title to refer to AC-3 Audio instead of AC-3 Streams.
-Moved change log from document to email.
-Moved key word conventions from separate section to introduction.
-In 2.1, added clarification that the Synchronization Information field
is for codec synchronization.
-Noted that figure 2 does not specify field sizes.
-In 4., clarified initialization of RTP time stamp.
-In the payload specific headers (5.1), changed the name of Time Code
Mode (TCM) to Time Stamp Mode (TSM) because, strictly, SMPTE time code
(defined for specific electrical transmission) is not included. Rather,
time stamps based on SMPTE time code notation are included.
-In 6.1, simplified definition of ptime.
-Changed language for change controller.
-In 6.2, clarified SDP usage and explained that special considerations
for offer/answer mode are not needed.
-In 7., added mention of an RTP profile imposing security considerations
and a reference to SRTP.
-In 10., added reference info for SRTP.

Best regards,
Brian

---
Brian Link
Dolby Laboratories, 100 Potrero Ave., San Francisco, CA 94103
phone: 415-558-0324  fax: 415-863-1373
email: [email-masked]   alt email: [email-masked]

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Sent: Tuesday, February 01, 2005 12:49 PM
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Subject: [AVT] I-D ACTION:draft-ietf-avt-rtp-ac3-02.txt

A New Internet-Draft is available from the on-line Internet-Drafts
directories.
This draft is a work item of the Audio/Video Transport Working Group of
the IETF.

	Title		: RTP Payload Format for AC-3 Streams
	Author(s)	: J. Flaks, et al.
	Filename	: draft-ietf-avt-rtp-ac3-02.txt
	Pages		: 11
	Date		: 2005-2-1
	
This document describes an RTP payload format for transporting AC-3
encoded audio data.  AC-3 is a high quality, multichannel audio coding
system used in US HDTV, DVD, cable and satellite television and other
media.  The RTP payload format as presented in this document includes
support for data fragmentation.

A URL for this Internet-Draft is:
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---

From: Colin Perkins <[email-masked]>
Date: Sun, 6 Feb 2005 11:04:52 +0000

Brian,

On 1 Feb 2005, at 23:28, Link, Brian wrote:
> the payload specific header since they are optional.

I agree that this resolves the issues, with the exception of the 
timestamp.

Colin