res_rtp_multicast: Ensure SSRC is set properly

This fixes a bug where the SSRC field on multicast RTP can be stuck at
0 which can cause problems for endpoints trying to make sense of
incoming streams.

(closes issue ASTERISK-22567)
Reported by: Simone Camporeale
Patches:
    22567_res_mulitcast_ssrc.patch uploaded by Simone Camporeale (License 6536)
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Merged revisions 400393 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 400394 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 400395 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@400397 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_rtp_multicast.c

@@ -260,15 +260,15 @@ static int multicast_rtp_write(struct ast_rtp_instance *instance, struct ast_fra
 	/* Construct an RTP header for our packet */
 	rtpheader = (unsigned char *)(f->data.ptr - hdrlen);
 	put_unaligned_uint32(rtpheader, htonl((2 << 30) | (codec << 16) | (multicast->seqno)));
-	put_unaligned_uint32(rtpheader + 4, htonl(multicast->lastts));
 	
 	if (ast_test_flag(f, AST_FRFLAG_HAS_TIMING_INFO)) {
 		put_unaligned_uint32(rtpheader + 4, htonl(f->ts * 8));
-	} 
-	else {
-		put_unaligned_uint32(rtpheader + 8, htonl(multicast->ssrc));
+	} else {
+		put_unaligned_uint32(rtpheader + 4, htonl(multicast->lastts));
 	}
 
+	put_unaligned_uint32(rtpheader + 8, htonl(multicast->ssrc));
+
 	/* Increment sequence number and wrap to 0 if it overflows 16 bits. */
 	multicast->seqno = 0xFFFF & (multicast->seqno + 1);