Subject: Re: [MMUSIC] Delay in RTSP responses from Server

From: Magnus Westerlund <[email-masked]>
Date: Thu, 01 Apr 2004 10:54:58 +0200

Hi Pranjal,

I agree that the transfer of RTSP messages are important. To my 
understanding however there is nothing that prevents a client to use the 
available QoS mechanism, like INTServ or DIFFServ. Otherwise I think 
there is very little that you can do at RTSP level to mitigate such a 
problem depending on network congestion. However the server is 
responsible to ensure that it is not accepting more sessions than it can 
handle.

There are also certain things a client can do, for example the STOP 
scenario you are presenting should not be obvious to a user. When the 
user presses PAUSE/STOP the client can freeze local playback immediately 
and take note of the NPT time. If it takes some time to get the response 
from the server, only waste network and server resources. So it is in 
fact only the cases where the client like something to start that will 
be obvious. I would also like to point out that after the first PLAY 
message, it is in most cases possible to synchronize the media for the 
new play range based on the already established synch between multiple 
media streams. The only thing that will not be accurate in such a 
scenario is the NPT of a certain media TS.

Cheers

Magnus

[email-masked] wrote:
> Hi,
>           I have developed a RTSP Client to interact with a VoD Server
  and it is streaming MPEG-2 Videos quite well. Sometimes I am observing
delays in getting response for PLAY,PUASE,TEARDOWN messages from the
Server. Assuming that the Server is responding intact under heavy
loaded condition the source of the problem goes to the Network
congestion. Under heavy video traffic when the network is overloaded
there are chances that small RTSP Messages are getting lost(and so TCP
retransmission at the Server will try sending again and again) and so
there is a delay in getting response. Is there any already existing
mechanism to implement End to end QoS mechanism for giving priority to
  RTSP Messages. Is there any already established method to overcome such
problems. I feel RTSP Control messages are very important from a viewers
perspective.Just thinking about a viewer who is not able to STOP the
video for minutes!!! I will be very obliged with the valuable
suggestions/comments.

> 
> Thanks,
> Pranjal 
> 
> 
> _______________________________________________
> mmusic mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/mmusic
> 

-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
----------------------------------------------------------------------
Ericsson AB                | Phone +46 8 4048287
Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: [email-masked]

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