Don't offer video to directmedia callee unless caller offered it as well

Make sure that when directmedia is enabled, that video is not offered to the
callee even if it supports it. p->vrtp will not exist since the caller didn't
offer video.

(closes issue #19195)
Reported by: one47
Patches: 
      sip_cant_add_video_rtp uploaded by one47 (license 23)



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.2@318331 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -10597,11 +10597,14 @@ static enum sip_result add_sdp(struct sip_request *resp, struct sip_pvt *p, int
 		doing_directmedia = (p->redirip.sin_addr.s_addr && p->redircodecs) ? TRUE : FALSE;
 		/* Check if we need video in this call */
 		if ((p->jointcapability & AST_FORMAT_VIDEO_MASK) && !p->novideo) {
-			if (p->vrtp) {
+			if (doing_directmedia && !(p->jointcapability & AST_FORMAT_VIDEO_MASK & p->redircodecs)) {
+				ast_debug(2, "This call needs video offers, but caller probably did not offer it!\n");
+			} else if (p->vrtp) {
 				needvideo = TRUE;
 				ast_debug(2, "This call needs video offers!\n");
-			} else
+			} else {
 				ast_debug(2, "This call needs video offers, but there's no video support enabled!\n");
+			}
 		}
 		/* Check if we need text in this call */
 		if ((p->jointcapability & AST_FORMAT_TEXT_MASK) && !p->notext) {