Subject: [MMUSIC] How to update media information during a streaming session?

From: Christian Sageder <[email-masked]>
Date: Wed, 6 Jul 2005 13:23:17 +0200

Hello all,

I am quite new to this mailing list and I have a question regarding the
possibility to update media information during a streaming session. 

The following scenario explains it: 

- A streaming server sends an audio/video stream to a client. This stream
contains multiple clips, e.g. as a radio broadcast which includes several
tracks.

- In parallel the streaming server should be able to provide additional
meta data to the client. This meta data has to be in sync with a clip
within the stream. The meta data we are looking for is some kind of media
title and some machine readable information like an ID or an URL

- With this information the client application should be able to provide
additional information about the currently played stream, e.g. displaying
the media title which is currently streamed and not only the information
"live stream" or equaling

My question is therefore:

Is there a standard way how a streaming server can pass additional /
updated information to a client which is in sync with the stream?

I have done some research within the RTSP and SDP standard, but I was not
able to find something to solve this issue. I think SDP and the future
extension of SDP allows us to pass all necessary information, but I was
not able to find anything how a streaming server can pass updated SDP
information to the client. It seams the SDP information is only send in
the initial phase, on request from the client (DESCRIBE), to the client.
There is also a draft about the use of ANNOUNCE, but for me it seams the
intention of this command was for an other purpose.

Any help on this issue is welcome.

Best Regards,
Christian Sageder

Sony Network Services Europe

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From: Magnus Westerlund <[email-masked]>
Date: Wed, 13 Jul 2005 16:41:18 +0200

Hi Christian,

> updated information to a client which is in sync with the stream?

Not to my knowledge. It might exist in some of the industry forums that 
has defined streaming related umbrella standards. However in that case I 
would expect them to be limited in usage.

When it comes to handling meta data at all I know that 3GPP has defined 
a asset information SDP Attribute. See chapter 5.3.3.7 in TS 26.234 (PSS).

> intention of this command was for an other purpose.

There has been discussion in the context of the announce draft:
http://www.ietf.org/internet-drafts/draft-ietf-mmusic-rtsp-announce-01.txt 
about providing updated SDP information.

I think one should consider the meta information as its own media stream 
that needs to be provided in sync with the media. Because publishing new 
SDP would generally mean media level changes which may require update of 
codec, transport or even RTSP state. Thus I don't think the usage of 
announce to distribute meta data is the best.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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