Add pass through support for Opus and VP8; Opus format attribute negotiation

This patch adds pass through support for Opus and VP8. That includes:

* Format attribute negotiation for Opus. Note that unlike some other codecs,
  the draft RFC specifies having spaces delimiting the attributes in addition
  to ';', so you have "attra=X; attrb=Y". This broke the attribute parsing in
  chan_sip, so a small tweak was also included in this patch for that.

* A format attribute negotiation module for Opus, res_format_attr_opus

* Fast picture update for VP8. Since VP8 uses a different RTCP packet number
  than FIR, this really is specific to VP8 at this time.

Note that the format attribute negotiation in res_pjsip_sdp_rtp was written
by mjordan. The rest of this patch was written completely by Lorenzo Miniero.

Review: https://reviewboard.asterisk.org/r/2723/

(closes issue ASTERISK-21981)
Reported by: Tzafrir Cohen
patches:
  asterisk_opus+vp8_passthrough_20130718.patch uploaded by lminiero (License 6518)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@397526 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 51 insertions, 3 deletions

diff --git a/res/res_rtp_asterisk.c b/res/res_rtp_asterisk.c
index db07e4ec5..6383b09e3 100644
--- a/res/res_rtp_asterisk.c
+++ b/res/res_rtp_asterisk.c
@@ -90,6 +90,8 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #define RTCP_PT_SDES    202
 #define RTCP_PT_BYE     203
 #define RTCP_PT_APP     204
+/* VP8: RTCP Feedback */
+#define RTCP_PT_PSFB    206
 
 #define RTP_MTU		1200
 
@@ -350,6 +352,9 @@ struct ast_rtcp {
 	double normdevrtt;
 	double stdevrtt;
 	unsigned int rtt_count;
+
+	/* VP8: sequence number for the RTCP FIR FCI */
+	int firseq;
 };
 
 struct rtp_red {
@@ -2414,7 +2419,7 @@ static int ast_rtcp_write(const void *data)
 	}
 
 	if (!res) {
-		/* 
+		/*
 		 * Not being rescheduled.
 		 */
 		ao2_ref(instance, -1);
@@ -2609,6 +2614,45 @@ static int ast_rtp_write(struct ast_rtp_instance *instance, struct ast_frame *fr
 		return 0;
 	}
 
+	/* VP8: is this a request to send a RTCP FIR? */
+	if (frame->frametype == AST_FRAME_CONTROL && frame->subclass.integer == AST_CONTROL_VIDUPDATE) {
+		struct ast_rtp *rtp = ast_rtp_instance_get_data(instance);
+		unsigned int *rtcpheader;
+		char bdata[1024];
+		int len = 20;
+		int ice;
+		int res;
+
+		if (!rtp || !rtp->rtcp) {
+			return 0;
+		}
+
+		if (ast_sockaddr_isnull(&rtp->rtcp->them)) {
+			/*
+			 * RTCP was stopped.
+			 */
+			return 0;
+		}
+
+		/* Prepare RTCP FIR (PT=206, FMT=4) */
+		rtp->rtcp->firseq++;
+		if(rtp->rtcp->firseq == 256) {
+			rtp->rtcp->firseq = 0;
+		}
+
+		rtcpheader = (unsigned int *)bdata;
+		rtcpheader[0] = htonl((2 << 30) | (4 << 24) | (RTCP_PT_PSFB << 16) | ((len/4)-1));
+		rtcpheader[1] = htonl(rtp->ssrc);
+		rtcpheader[2] = htonl(rtp->themssrc);
+		rtcpheader[3] = htonl(rtp->themssrc);	/* FCI: SSRC */
+		rtcpheader[4] = htonl(rtp->rtcp->firseq << 24);			/* FCI: Sequence number */
+		res = rtcp_sendto(instance, (unsigned int *)rtcpheader, len, 0, &rtp->rtcp->them, &ice);
+		if (res < 0) {
+			ast_log(LOG_ERROR, "RTCP FIR transmission error: %s\n", strerror(errno));
+		}
+		return 0;
+	}
+
 	/* If there is no data length we can't very well send the packet */
 	if (!frame->datalen) {
 		ast_debug(1, "Received frame with no data for RTP instance '%p' so dropping frame\n", instance);
@@ -2660,6 +2704,8 @@ static int ast_rtp_write(struct ast_rtp_instance *instance, struct ast_frame *fr
 		case AST_FORMAT_SIREN7:
 		case AST_FORMAT_SIREN14:
 		case AST_FORMAT_G719:
+		/* Opus */
+		case AST_FORMAT_OPUS:
 			/* these are all frame-based codecs and cannot be safely run through
 			   a smoother */
 			break;
@@ -3353,6 +3399,8 @@ static struct ast_frame *ast_rtcp_read(struct ast_rtp_instance *instance)
 					message_blob);
 			break;
 		case RTCP_PT_FUR:
+		/* Handle RTCP FIR as FUR */
+		case RTCP_PT_PSFB:
 			if (rtcp_debug_test_addr(&addr)) {
 				ast_verbose("Received an RTCP Fast Update Request\n");
 			}
@@ -4174,14 +4222,14 @@ static int ast_rtp_sendcng(struct ast_rtp_instance *instance, int level)
 	payload = ast_rtp_codecs_payload_code(ast_rtp_instance_get_codecs(instance), 0, NULL, AST_RTP_CN);
 
 	level = 127 - (level & 0x7f);
-	
+
 	rtp->dtmfmute = ast_tvadd(ast_tvnow(), ast_tv(0, 500000));
 
 	/* Get a pointer to the header */
 	rtpheader = (unsigned int *)data;
 	rtpheader[0] = htonl((2 << 30) | (payload << 16) | (rtp->seqno));
 	rtpheader[1] = htonl(rtp->lastts);
-	rtpheader[2] = htonl(rtp->ssrc); 
+	rtpheader[2] = htonl(rtp->ssrc);
 	data[12] = level;
 
 	res = rtp_sendto(instance, (void *) rtpheader, hdrlen + 1, 0, &remote_address, &ice);