Subject: [MMUSIC] RTSP pipelining revisited

From: David Viamonte <[email-masked]>
Date: Wed, 26 Apr 2006 12:30:57 +0200

Dear mmusic experts, 

I would like to request some feedback about a question on RTSP and 3GPP PSS. I 
have been working and doing some research around streaming over wireless during 
the last years, so that’s where I am coming from. 

My understanding is that there is no real support for RTSP pipelining in 
standard RTSP. As far as I understand, this also stands for RTSP 2.0 I-D, but 
please correct me if I’m wrong. 

I was wondering that enabling RTSP pipelining is an interesting area to 
consider, particularly as we see that interactivity and fast session setup are 
key to keep user’s attention on the service. 

Additionally, enabling early activation of Secondary PDP-Context(s) in a 3GPP 
PSS environment would be a good idea (3GPP TS 26.234). All in all, IMMO I think 
some time could be saved in session setup by defining a proper standard 
extension to RTSP. Defining it under a feature tag would keep backwards 
compatibility untouched. 

Just wanted to trigger some discussion to see if anyone believes this could be 
an interesting area to think about. In case you believe it doesn’t make any 
sense, I am happy to hear your thoughts as well. 

Thanks in advance and kind regards, 

David 

PS.- I know that with WLAN and HSxPA out there, the gains of pipelining RTSP 
may be reduced. Still, in cases when signalling is carried over relatively 
narrowband bearers –leaving broadband connections for media- I believe a sort 
of extension would possibly help... 

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From: Magnus Westerlund <[email-masked]>
Date: Wed, 26 Apr 2006 14:14:59 +0200

Hi David,

Request pipelining is allowed. However it can't be applied between the 
first and second SETUP for example. Also between the last SETUP and the 
first PLAY there is a restriction on doing request pipelining to avoid 
needing to deal with the unknown state. I think what you should call 
this is session establishment optimization.

I think there is a general interest in optimizing RTSP in regards to the 
time it takes to do session establishment. However, I think that just 
discussing it will not make it happen, because that have been the state 
of things for the last 6 years. If you like something to happen in this 
area you will need to step in and start proposing real solution and 
actually write specification proposals for how to accomplish it.

Cheers

Magnus

-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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