<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Hello all,<DIV><BR class="khtml-block-placeholder"></DIV><DIV>I am working on the Iaxclient project (<A href="http://sourceforge.net/projects/iaxclient">http://sourceforge.net/projects/iaxclient</A>). We are trying to add video support to our code, but we have some problems with video codec negotiation with Asterisk. </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Please see message included below. I've already sent this to iaxclient-devel and asterisk-video lists, but I figured that the general Asterisk development community might have some insightful opinions...</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Thanks in advance,</DIV><DIV>Mihai<BR><DIV><BR><DIV>Begin forwarded message:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>From: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">Mihai Balea <<A href="mailto:mihai@hates.ms">mihai@hates.ms</A>></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Date: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">October 23, 2006 11:45:13 AM EDT</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>To: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">Iax Developer List <<A href="mailto:iaxclient-devel@lists.sourceforge.net">iaxclient-devel@lists.sourceforge.net</A>></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Cc: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><A href="mailto:asterisk-video@lists.digium.com">asterisk-video@lists.digium.com</A></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><B>Subject: </B></FONT><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><B>[Iaxclient-devel] Video codec negotiation in IAX</B></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV> <DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Hello all,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">As you may already know, I am working on adding video support to <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">iaxclient.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">It appears however that IAX's support for video codec negotiation is <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">lacking.<SPAN class="Apple-converted-space"> </SPAN>I am no IAX expert, but from what I can see, there are to <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">ways of doing codec negotiation in IAX:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">- use the FORMAT and CAPABILITY IEs.<SPAN class="Apple-converted-space"> </SPAN>This allows you to specify one <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">preferred codec and a list of acceptable codecs. This is the way <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">iaxclient does codec negotiation at this time.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">- use the CODEC PREFS IE.<SPAN class="Apple-converted-space"> </SPAN>This allows you to specify a list of <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">acceptable codecs, in order of preference.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The problem with video is that you need to negotiate two codecs at <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">the same time (one for video and one for audio). Unfortunately, none <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">of the above mentioned methods are suitable for this.<SPAN class="Apple-converted-space"> </SPAN>The way I see <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">it, there are several ways of addressing this:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">1. use a VIDEO FORMAT IE, in addition to FORMAT and CAPABILITY.<SPAN class="Apple-converted-space"> </SPAN>The <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">CAPABILITY IE will contain acceptable video codecs as well as audio.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">2. use a VIDEO CODEC PREFS IE in addition to the current CODEC PREFS <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">IE.<SPAN class="Apple-converted-space"> </SPAN>This will more flexible since it allows for video codec <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">preference order.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">3. use the current FORMAT and CAPABILITY and change the semantics of <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">FORMAT to allow a video codec as well as an audio codec. This might <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">be easiest to implement.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">As a long term solution, I'm inclined to go with #2 since it provides <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">the maximum amount of flexibility.<SPAN class="Apple-converted-space"> </SPAN>However I would like to hear any <SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">suggestions you might have regarding this issue...</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Thanks in advance,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Mihai</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">-------------------------------------------------------------------------</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Using Tomcat but need to do more? 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