On Tue, Oct 30, 2018 at 4:50 PM Andreas Wehrmann <a.wehrm...@yandex.com> wrote: > > Hello folks, > > I'm currently writing a module for Asterisk > to make it divert a video stream to an external videoserver. > The scenario is this: > > - some external participant is calling into Asterisk (offering audio+video) > > - using SIP session supplements: in the incoming (INVITE) message callback, > a video session is set up on the videoserver (actually: this happens > always, regardless of what is offered) > > - using the dialplan, the call is routed to another PBX supporting audio only > (but video codecs are enabled on our side, so video will be offered by > Asterisk) > > - when the other PBX answers, I'm using SIP session supplements to determine > whether the call answered by the other PBX supports video > -- if video is supported, my module does nothing > -- if video is rejected, I manipulate the SDP inside to make it seem to > Asterisk > as if video actually was supported by inserting connection info pointing > to the video server > > What I've just described does work. > The SIP supplement is registered with a response priority of > AST_SIP_SESSION_BEFORE_MEDIA > and handles the INVITE method only. > > However, what doesn't work is if the external participant initially calls in > with audio only and enables video later by sending a reINVITE. > > I do not get a callback from my already registered SIP supplement when the > other PBX > responds to the reINVITE in order to give me a chance to manipulate the SDP. > I guess this is because the session was already active and thus "AFTER_MEDIA". > > When I register a SIP supplement with "AST_SIP_SESSION_AFTER_MEDIA", > I do indeed get a callback for the reINVITE response, > but that happens too late, since SDP negotiation inside Asterisk has already > happened. > > I then tried to register an SDP handler (just to see what callbacks I get and > whether they might be useful). > The only callback I receive is defer_incoming_sdp_stream() for the reINVITE > that my Asterisk receives > which doesn't seem too useful for what I'm trying to do. > > Since I had no more ideas left, I then tried to hook into PJSIP directly > by providing a pjsip_module that implements the on_rx_response() callback. > > That doesn't really work either, because the callback never fired. > After I played around with module priority the callback eventually fired but > I was unable to get the TSX and dialog references from PJ > (probably because the module got called too early?). > However I need those to get the corresponding ast_sip_session. > > At this point, I don't know how to proceed. > Is there a way to hook into reINVITE responses to achieve what I'm trying to > do?
Good question! Sounds like an interesting project. For the purpose of pure curiosity, do you mind if I ask why you're trying to send the video to a separate server? With regards to your specific questions, I'm guessing this is something that George Joseph or Josh Colp might have a few more opinions about. -- Matthew Fredrickson Digium - A Sangoma Company | Asterisk Project Lead 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- Astricon is coming up October 9-11! Signup is available at: https://www.asterisk.org/community/astricon-user-conference asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
