Re: [GnomeMeeting-devel-list] Questions on gnomemeeting-opal's src/endpoint.cpp

[Damien Sandras <dsandras seconix com>]

Le mercredi 01 juin 2005 à 22:15 +0200, Julien PUYDT a écrit :
> Damien Sandras a écrit :
> >>1) the function GetRegisteredAccounts uses an ill-named int "sip" to 
> >>denote an integer which in fact adds h323 and sip accounts' numbers ; I 
> >>propose the following trivial patch to rename it to "number":
> >>@@ -2554,13 +2554,13 @@
> >>  int
> >>  GMEndPoint::GetRegisteredAccounts ()
> >>  {
> >>-  int sip = 0;
> >>+  int number = 0;
> >>
> >>-  sip = sipEP->GetRegisteredAccounts ();
> >>+  number = sipEP->GetRegisteredAccounts ();
> >>    if (h323EP->IsRegisteredWithGatekeeper ())
> >>-    sip++;
> >>+    number++;
> >>
> >>-  return sip;
> >>+  return number;
> >>  }
> 
> > I'm in Germany, perhaps Migras can commit it? Or you?
> 
> Well, I waited and waited, but Migras didn't commit it, so I finally did 
> it... I really don't like cvs.
> 
> >>2) SetTransferCallToken and GetTransferCallToken don't use 
> >>PWaitAndSignal but explicitly do the Wait, something, then the Signal ; 
> >>why is it so?
> > 
> > It comes from the old gnomemeeting, currently being transferred doesn't
> > work, so it is not used anymore. So that code needs to be reviewed once
> > I get "being transferred" working.
> 
> Ok.
> 
> >>3) I don't understand what all those "pc:" thingies are about (as seen 
> >>in AddRouteEntry or OpalManager::SetupCall function calls.
> > To summarize (Ive not had time to write my opal howto here as tehre is
> > no power and my battery is weak):
> > - An OpalManager manages several endpoints
> 
> Ok.
> 
> > - Each endpoint is able to do calls following a protocol
> 
> Say SIP or H323. Ok. Explains why there are src/sipendpoint.cpp and 
> src/h323endpoint.cpp.
> 
> > - In the future, if the protocols are different, there will be automatic
> > translation (for proxies and gateways) and automatic mixing, for now, it
> > is not the case
> 
> I'm not sure I'm even supposed to understand that sentence ;-)

Same here ;)

> 
> > When you are doing a call, you create an OpalCall object.
> 
> More precisely: the endpoint creates an OpalCall object?


The OpalManager I think.



> 
> > Each calls has
> > several OpalConnections involved,
> 
> I don't get what an OpalConnection is from the rest of your 
> explanations: are they some sort of members of a room and share all 
> media in/out.

Yes sort of. They imply OpalMediaStreams, managed by a Patch and a
Sink/Source.

> 
> > following the protocol. If you are
> > doing a SIP Call, you create an OpalCall object with 2 connections :
> > - 1 SIPConnection
> > - 1 PCSSConnection
> > The SIPConnection is managed by the SIPEndPoint
> > The PCSSConnection is managed by the PCSSEndPoint, which is not a real
> > protocol, with transcoding, but the PC Sound System endpoint.
> 
> This is what makes me think those OpalConnections are some sort of 
> members of a room. One of the occupants is the user and the other is the 
> network. Right?

Right. But for a gateway, you could have a SIP and H.323 connection, and
no "user" connection.

> 
> > In the future, for gateways, you will be able to remove the
> > PCSSConnection and replace it by an H.323 Connection for example.
> 
> This adds in the fact that they are some sort of room member.
> 
> > Anyway, in GnomeMeeting's case, each call only contains 2 connections,
> > one to the LOCAL PCSSEndPoint (PCSSConnection) and one to the REMOTE
> > SIPEndPoint (SIPConnection).
> 
> Once you confirm my notion of room member, I guess I'll be more than ok 
> with it.

Yes, your metaphore is correct.

> 
> > When you are being transferred, you keep the PCSSConnection in the call,
> > and remove the SIPConnection to replace it by another one to another
> > endpoint.
> 
> Idem.
> 
> > Those are the basics.
> 
> Hope I understood well enough. Would it be possible to put more than two 
> connections in a call (multiconference) [of course if the network is 
> able to cope with it]?

Yes, ie my "auto-mixing" sentence you didn't understand here above.

> 
> > An OpalMediaStream is the connection between a source and a sink.
> > Obviously you will for example have : PCM-16 -> G.711 codec (encoding)
> > and G.711 -> PCM-16 (decoding). Because an OpalMediaStream related to a
> > PCSSConnection is of type PCM-16, for example.
> 
> Is an OpalConnection a collection of OpalMediaStreams (one for sound 
> input, another for sound output ; in some time another for video input 
> and a fourth for video output...)?
> 

Yes, there is an OpalMediaStream from G.711 to PCM-16 and another in the
reverse direction. Sometimes, there can be direct media bypass (SIP to
SIP without codec conversion in the case of a gateway where an OPALCall
object contains 2 SIP connections).
-- 
 _      Damien Sandras
(o-     GnomeMeeting: http://www.gnomemeeting.org/
//\     FOSDEM 2005 : http://www.fosdem.org
v_/_    H.323 phone : callto:ils.seconix.com/dsandras seconix com