Subject: [AVT] [Fwd: I-D Action:draft-schierl-avt-rtp-multi-session-transmission-00.txt]

From: Thomas Schierl <[email-masked]>
Date: Tue, 28 Oct 2008 13:31:50 +0100

Dear all,

As you may have already noticed, we submitted yesterday the eagerly 
awaited draft on multi-session and multi-source related issues.

There will be a presentation and a discussion at the next meeting during 
one of the avt sessions.

Best regards,
Thomas

-- 
Thomas Schierl
--------------
Fraunhofer HHI

----
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MEDICA 2008 / Duesseldorf, Germany / 19 - 22 November 2008 / Hall 16, Booth D55
http://www.medica.de

Subject: I-D Action:draft-schierl-avt-rtp-multi-session-transmission-00.txt
From: [email-masked]
To: [email-masked]
Date: Sun, 26 Oct 2008 23:45:01 -0700 (PDT)
List-Id: Internet Draft Announcements only <i-d-announce.ietf.org>

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title           : Multi-Session and Multi-Source Transmission in the Real-Time Transport Protocol (RTP)
	Author(s)       : T. Schierl, J. Lennox
	Filename        : draft-schierl-avt-rtp-multi-session-transmission-00.txt
	Pages           : 22
	Date            : 2008-10-26

In this draft, we discuss problems related to multi-session and
multi-source transmission using the Real-Time Transport Protocol
(RTP).  Most of the input to this draft is taken from email
discussion.  Multi-session and multi-source transmission is motivated
by media data which allows for different transport layer treatment of
parts of the media.  This is typically the case for layered media.
Multi-session transmission is when media data from a single media
source is split over multiple RTP sessions.  Single-session multi-
source transmission (from now on just called "multi-source
transmission") is when data from a single media source is sent as
several RTP streams in the same RTP session.  The main problems
discussed are the mechanisms used for data alignment and source
correlation.  This draft gives further an overview of payload formats
using multi-sessions/multi-source transmission and highlights other
transport related issues.  The draft concludes with recommendations
for the discussed problems.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-schierl-avt-rtp-multi-session-transmission-00.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

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implementation to automatically retrieve the ASCII version of the
Internet-Draft.
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From: <[email-masked]>
Date: Fri, 31 Oct 2008 17:54:43 +0200

Good draft! Just a few comments:

- There is one problem that is common for all timing based data
alignment methods (documented in sections 7.1, 7.2.1, 7.2.1, 7.2.3, and
7.2.4) but has not been mentioned in the draft. The timing based methods
themselves do not always work for encoding schemes wherein the decoding
order of coded data units is different from the output/playout order
(i.e. media timestamp order). Cases wherein the methods do not work well
include transporting media with pure temporal scalability using
multi-session transmission and when some packet loss patterns happen
(see detailed discussions in
http://research.nokia.com/files/SVC_cross_layer_decoder_order_recovery.p
pt). Thus, these methods may have to be used together with some payload
specific mechanisms, e.g. Empty NAL units as used by the NI-T and NI-TC
modes defined in the SVC payload draft, to make them complete.

- Note that in SVC, an enhancement may also be independent of the base
layer, similar as in MVC that a non-base view may be independent of the
base view. In addition, even though the current MVC codec may not fly,
it is likely some kind of multiview codecs will fly in the future.
Therefore, mandating using of a single SSRC may not be ideal, even
though that might be OK for now for SVC, for simplicity. However, if
possible, to have a complete and future-proof design would be desirable.
Therefore,.it should worth a discussion on potential issues and
solutions of using multiple SSRC values for different RTP sessions
transporting one scalable/embeded bitstream. 

- In multi-session transmission of scalable/embeded speech and audio,
e.g. G.718, though different layers may have different sampling rates,
there is no problem to use a common RTP timestamp clockrate, as is the
case in
http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-g718-00.txt.

BR, YK

>-----Original Message-----
>From: [email-masked] [mailto:[email-masked]] On 
>Behalf Of ext Thomas Schierl
>Sent: 28 October, 2008 14:32
>To: avt
>Cc: Jonathan Lennox; Even,Roni
>Subject: [AVT] [Fwd: 
>I-DAction:draft-schierl-avt-rtp-multi-session-transmission-00.txt]
>
>Dear all,
>
>As you may have already noticed, we submitted yesterday the 
>eagerly awaited draft on multi-session and multi-source related issues.
>
>There will be a presentation and a discussion at the next 
>meeting during one of the avt sessions.
>
>Best regards,
>Thomas
>
>--
>Thomas Schierl
>--------------
>Fraunhofer HHI
>
>
>
>
>
>----
>Visit us at
>