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Re: [Linphone-developers] [PATCH] DCCP Support

From: Simon Morlat
Subject: Re: [Linphone-developers] [PATCH] DCCP Support
Date: Thu, 20 Jun 2013 18:56:05 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6

Hi Samuel,

I apologize for my belated answer.
Congratulations for all the work you did in Linphone. I reviewed all your commits. This is very impressive and this looks pretty well written.
I did not know the existence of DCCP, and thus I also thank you for pointing this to us.

I have very quickly read the DCCP rfc and I would like to know if you had any opinion regarding the way it works with NATs.
Indeed  I understand that is connection oriented (like TCP), which means there are client and server sockets.
Do NATs support DCCP ?

Thank you very much,


Le 11/06/2013 23:53, Samuel Jero a écrit :
As part of my masters work, I have added support for streaming media
over the Datagram Congestion Control Protocol (DCCP) to linphone. DCCP
is a relatively new protocol (2006) developed by the IETF to provide
congestion control without reliability for applications like VoIP and
video streaming (RFC4340-- I would
like to contribute this work back to the main Linphone code-base, if
possible, so that others can utilize it.

My patches consist of three main parts:
1)Adding support for DCCP to oRTP. This involves substantial changes to
rtpsession_inet.c, particularly since DCCP is a connection-oriented
protocol, unlike UDP.
2)Updating the bitrate control mechanisms in mediastreamer2 and the
feedback it receives from oRTP. DCCP provides feedback to the
application as to how fast it is allowed to send and when it needs to
slow down. This feedback is distinctly more rapid that RTCP reports, so
I utilize it in preference to RTCP for bitrate control.
3)Updating APIs throughput oRTP, mediastreamer2, and liblinphone to
allow selection of transport protocol.

As the patches to add DCCP support are fairly significant, I have
created a repository on github containing the changes:
oRTP: git://   branch: for-linphone
git://   branch:
linphone: git://   branch: for-linphone
These branches base off of the master branch from
git:// as of 2013-06-10.

Direct links to my commits are below:

Any comments on these patches would be appreciated. I can try to split
out a large number of smaller patches if that would help, but a lot of
the changes are interrelated.


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