Subject: RE: [MMUSIC] question regarding presentation with aggregate control

From: "Patankar, Sujay" <[email-masked]>
Date: Tue, 2 Jan 2007 16:36:07 +0530

Hi,
In the following excerpt from RFC 2326:
" Presentation:
          A set of one or more streams presented to the client as a
          complete media feed, using a presentation description as
          defined below. In most cases in the RTSP context, this implies
          aggregate control of those streams, but does not have to."

Does it mean that there can be a presentation with more than one
streams, and still non-aggregate control? The draft 2326bis-14 uses the
wording:

" Presentations with more than one media stream are *often* handled in
RTSP under aggregate control."

(emphasis on 'often' is mine) is it 'often' or is it 'always'?

If it is indeed 'often', then can anyone please give me an example of a
presentation with more than one media, but no aggregate control?

Thanks,
Sujay.

-----Original Message-----
From: Magnus Westerlund [mailto:[email-masked]] 
Sent: Friday, 22 Dec, 2006 15:02
To: Kylin Wei
Cc: Patankar, Sujay; 'mmusic (E-mail)'
Subject: Re: [MMUSIC] question regarding aggregate control

Hi,

Sujay, I would recommend that you read the spec once more. I would also 
suggest that you have a look on how the RTSP 2.0 draft proposes to 
clarify things:
http://tools.ietf.org/wg/mmusic/draft-ietf-mmusic-rfc2326bis/

However the answer to your question is actually in the parts you removed

in the email. In 14.2 of RFC 2326 the two media streams are set up in 
aggregate control. Thus a single teardown on the aggregate control URI 
will remove all state for both media streams.

Cheers

Magnus

Kylin Wei skrev:
> 11.6 TEARDOWN
> 
>    The TEARDOWN client to server request stops the stream delivery for
>    the given URI, freeing the resources associated with it. A TEARDOWN
>    request MAY be performed on either an aggregated or a media control
>    URI. However some restrictions apply depending on the current
state.
>    The TEARDOWN request SHALL contain a Session header indicating what
>    session the request applies to.
> 
>    A TEARDOWN using the aggregated control URI or the media URI in a
>    session under non-aggregated control (single media session) MAY be
>    done in any state (Ready, and Play). A successful request SHALL
>    result in that media delivery is immediately halted and the session
>    state is destroyed. This SHALL be indicated through the lack of a
>    Session header in the response.
> 
>    A TEARDOWN using a media URI in an aggregated session MAY only be
>    done in Ready state. Such a request only removes the indicated
media
>    stream and associated resources from the session. This may result
in
>    that a session returns to non-aggregated control, due to that it
only
>    contains a single media after the requests completion.  A session
>    that will exist after the processing of the TEARDOWN request SHALL
in
>    the response to that TEARDOWN request contain a Session header.
Thus
>    the presence of the Session header indicates to the receiver of the
>    response if the session is still existing or has been removed.
> 
> Kylin Wei 
>> -----Original Message-----
>> From: Patankar, Sujay [mailto:[email-masked]]
>> Sent: Friday, December 22, 2006 12:05 PM
>> To: mmusic (E-mail)
>> Subject: [MMUSIC] question regarding aggregate control
>>
>> Hi,
>> In section 14.2 of RFC 2326, we see that a session under aggregate
>> control is being setup.
>> There is a single DESCRIBE request
>> DESCRIBE rtsp://foo/twister RTSP/1.0
>>
>> And two separate SETUP requests:
>> SETUP rtsp://foo/twister/audio RTSP/1.0
>> SETUP rtsp://foo/twister/video RTSP/1.0
>>
>> Will the client have to send a single TEARDOWN like the DESCRIBE, or
>> will it have to send two separate TEARDOWNs, or is it for the client
to
>> decide?
>> Thanks,
>> Sujay.
>>
>> _______________________________________________
>> mmusic mailing list
>> [email-masked]
>> https://www1.ietf.org/mailman/listinfo/mmusic
> 
> 
> 
> _______________________________________________
> mmusic mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/mmusic
> 

-- 

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVA/A
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Ericsson AB                | Phone +46 8 4048287
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S-164 80 Stockholm, Sweden | mailto: [email-masked]
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