Support for transport-wide CC on outgoing streams

ice.c

@@ -3508,7 +3508,7 @@ static gint rtcp_transport_wide_cc_stats_comparator(gconstpointer item1, gconstp
 static gboolean janus_ice_outgoing_transport_wide_cc_feedback(gpointer user_data) {
 	janus_ice_handle *handle = (janus_ice_handle *)user_data;
 	janus_ice_stream *stream = handle->stream;
-	if(stream && stream->do_transport_wide_cc) {
+	if(stream && stream->video_send && stream->do_transport_wide_cc) {
 		/* Create a transport wide feedback message */
 		size_t size = 1300;
 		char rtcpbuf[1300];
@@ -4096,6 +4096,14 @@ static gboolean janus_ice_outgoing_traffic_handle(janus_ice_handle *handle, janu
 					/* ... but only if this isn't a retransmission (for those we already set it before) */
 					header->ssrc = htonl(video ? stream->video_ssrc : stream->audio_ssrc);
 				}
+				/* Set the transport-wide sequence number, if needed */
+				if(video && stream->transport_wide_cc_ext_id > 0) {
+					stream->transport_wide_cc_out_seq_num++;
+					if(janus_rtp_header_extension_set_transport_wide_cc(pkt->data, pkt->length,
+							stream->transport_wide_cc_ext_id, stream->transport_wide_cc_out_seq_num) < 0) {
+						JANUS_LOG(LOG_ERR, "[%"SCNu64"] Error setting transport wide CC sequence number...\n", handle->handle_id);
+					}
+				}
 				/* Keep track of payload types too */
 				if(!video && stream->audio_payload_type < 0) {
 					stream->audio_payload_type = header->type;
@@ -4374,6 +4382,14 @@ void janus_ice_relay_rtp(janus_ice_handle *handle, janus_plugin_rtp *packet) {
 		extheader->length = 0;
 		/* Iterate on all extensions we need */
 		char *index = extensions + 4;
+		/* Check if we need to add the transport-wide CC extension */
+		if(packet->video && handle->stream->transport_wide_cc_ext_id > 0) {
+			*index = (handle->stream->transport_wide_cc_ext_id << 4) + 1;
+			/* We'll actually set the sequence number later, when sending the packet */
+			memset(index+1, 0, 2);
+			index += 3;
+			extlen += 3;
+		}
 		/* Check if we need to add the mid extension */
 		if(handle->stream->mid_ext_id > 0) {
 			char *mid = packet->video ? handle->video_mid : handle->audio_mid;

ice.h

@@ -414,6 +414,8 @@ struct janus_ice_stream {
 	gboolean do_transport_wide_cc;
 	/*! \brief Transport wide cc rtp ext ID */
 	gint transport_wide_cc_ext_id;
+	/*! \brief Last sent transport wide seq num */
+	guint16 transport_wide_cc_out_seq_num;
 	/*! \brief Last received transport wide seq num */
 	guint32 transport_wide_cc_last_seq_num;
 	/*! \brief Last transport wide seq num sent on feedback */

janus.c

@@ -3378,7 +3378,7 @@ json_t *janus_plugin_handle_sdp(janus_plugin_session *plugin_session, janus_plug
 			}
 		}
 		/* Make sure we don't send the rid/repaired-rid attributes when offering ourselves */
-		int mid_ext_id = 0, audiolevel_ext_id = 0, videoorientation_ext_id = 0;
+		int mid_ext_id = 0, transport_wide_cc_ext_id = 0, audiolevel_ext_id = 0, videoorientation_ext_id = 0;
 		GList *temp = parsed_sdp->m_lines;
 		while(temp) {
 			janus_sdp_mline *m = (janus_sdp_mline *)temp->data;
@@ -3388,6 +3388,8 @@ json_t *janus_plugin_handle_sdp(janus_plugin_session *plugin_session, janus_plug
 				if(a->name && a->value) {
 					if(strstr(a->value, JANUS_RTP_EXTMAP_MID))
 						mid_ext_id = atoi(a->value);
+					else if(strstr(a->value, JANUS_RTP_EXTMAP_TRANSPORT_WIDE_CC))
+						transport_wide_cc_ext_id = atoi(a->value);
 					else if(strstr(a->value, JANUS_RTP_EXTMAP_AUDIO_LEVEL))
 						audiolevel_ext_id = atoi(a->value);
 					else if(strstr(a->value, JANUS_RTP_EXTMAP_VIDEO_ORIENTATION))
@@ -3406,6 +3408,10 @@ json_t *janus_plugin_handle_sdp(janus_plugin_session *plugin_session, janus_plug
 		}
 		if(ice_handle->stream && ice_handle->stream->mid_ext_id != mid_ext_id)
 			ice_handle->stream->mid_ext_id = mid_ext_id;
+		if(ice_handle->stream && ice_handle->stream->transport_wide_cc_ext_id != transport_wide_cc_ext_id) {
+			ice_handle->stream->do_transport_wide_cc = transport_wide_cc_ext_id > 0 ? TRUE : FALSE;
+			ice_handle->stream->transport_wide_cc_ext_id = transport_wide_cc_ext_id;
+		}
 		if(ice_handle->stream && ice_handle->stream->audiolevel_ext_id != audiolevel_ext_id)
 			ice_handle->stream->audiolevel_ext_id = audiolevel_ext_id;
 		if(ice_handle->stream && ice_handle->stream->videoorientation_ext_id != videoorientation_ext_id)

rtcp.c

@@ -22,6 +22,26 @@
 #include "rtcp.h"
 #include "utils.h"
 
+
+/* Transport CC statuses */
+typedef enum janus_rtp_packet_status {
+	janus_rtp_packet_status_notreceived = 0,
+	janus_rtp_packet_status_smalldelta = 1,
+	janus_rtp_packet_status_largeornegativedelta = 2,
+	janus_rtp_packet_status_reserved = 3
+} janus_rtp_packet_status;
+static const char *janus_rtp_packet_status_description(janus_rtp_packet_status status) {
+	switch(status) {
+		case janus_rtp_packet_status_notreceived: return "notreceived";
+		case janus_rtp_packet_status_smalldelta: return "smalldelta";
+		case janus_rtp_packet_status_largeornegativedelta: return "largeornegativedelta";
+		case janus_rtp_packet_status_reserved: return "reserved";
+		default: break;
+	}
+	return NULL;
+}
+
+
 gboolean janus_is_rtcp(char *buf, guint len) {
 	if (len < 8)
 		return FALSE;
@@ -134,7 +154,7 @@ guint32 janus_rtcp_get_receiver_ssrc(char *packet, int len) {
 	return 0;
 }
 
-/* Helper to handle an incoming SR: triggered by a call to janus_rtcp_fix_ssrc with fixssrc=0 */
+/* Helper to handle an incoming SR: triggered by a call to janus_rtcp_fix_ssrc with a valid context pointer */
 static void janus_rtcp_incoming_sr(janus_rtcp_context *ctx, janus_rtcp_sr *sr) {
 	if(ctx == NULL)
 		return;
@@ -146,6 +166,103 @@ static void janus_rtcp_incoming_sr(janus_rtcp_context *ctx, janus_rtcp_sr *sr) {
 	ctx->lsr = (ntp >> 16);
 }
 
+/* Helper to handle an incoming transport-cc feedback: triggered by a call to janus_rtcp_fix_ssrc a valid context pointer */
+static void janus_rtcp_incoming_transport_cc(janus_rtcp_context *ctx, janus_rtcp_fb *twcc, int total) {
+	if(ctx == NULL || twcc == NULL || total < 16)
+		return;
+	/* Parse the header first */
+	uint8_t *data = (uint8_t *)twcc->fci;
+	uint16_t base_seq = 0, status_count = 0;
+	uint32_t reference = 0;
+	uint8_t fb_pkt = 0;
+	memcpy(&base_seq, data, sizeof(uint16_t));
+	base_seq = ntohs(base_seq);
+	memcpy(&status_count, data+2, sizeof(uint16_t));
+	status_count = ntohs(status_count);
+	memcpy(&reference, data+4, sizeof(uint32_t));
+	reference = ntohl(reference) >> 8;
+	fb_pkt = *(data+7);
+	JANUS_LOG(LOG_HUGE, "[TWCC] seq=%"SCNu16", psc=%"SCNu16", ref=%"SCNu32", fbpc=%"SCNu8"\n",
+		base_seq, status_count, reference, fb_pkt);
+	/* Now traverse the feedback: packet chunks first, and then recv deltas */
+	total -= 16;
+	data += 8;
+	int psc = status_count;
+	uint16_t chunk = 0;
+	uint8_t t = 0, ss = 0, s = 0, length = 0;
+	/* Iterate on all packet chunks */
+	JANUS_LOG(LOG_HUGE, "[TWCC] Chunks:\n");
+	int num = 0;
+	GList *list = NULL;
+	while(psc > 0 && total > 0) {
+		num++;
+		memcpy(&chunk, data, sizeof(uint16_t));
+		chunk = ntohs(chunk);
+		t = (chunk & 0x8000) >> 15;
+		if(t == 0) {
+			/* Run length */
+			s = (chunk & 0x6000) >> 13;
+			length = (chunk & 0x1FFF);
+			JANUS_LOG(LOG_HUGE, "  [%d] t=run-length, s=%s, l=%"SCNu16"\n", num,
+				janus_rtp_packet_status_description(s), length);
+			while(length > 0 && psc > 0) {
+				list = g_list_append(list, GUINT_TO_POINTER(s));
+				length--;
+				psc--;
+			}
+		} else {
+			/* Status vector */
+			ss = (chunk & 0x4000) >> 14;
+			length = (s ? 7 : 14);
+			JANUS_LOG(LOG_HUGE, "  [%d] t=status-vector, ss=%s, l=%"SCNu16"\n", num,
+				s ? "2-bit" : "bit", length);
+			while(length > 0 && psc > 0) {
+				if(!ss)
+					s = (chunk & (1 << (length-1))) ? janus_rtp_packet_status_smalldelta : janus_rtp_packet_status_notreceived;
+				else
+					s = (chunk & (3 << (2*length-2))) >> (2*length-2);
+				list = g_list_append(list, GUINT_TO_POINTER(s));
+				length--;
+				psc--;
+			}
+		}
+		total -= 2;
+		data += 2;
+	}
+	/* Iterate on all recv deltas */
+	JANUS_LOG(LOG_HUGE, "[TWCC] Recv Deltas (%d/%"SCNu16"):\n", g_list_length(list), status_count);
+	num = 0;
+	uint16_t delta = 0;
+	uint32_t delta_us = 0;
+	GList *iter = list;
+	while(iter != NULL && total > 0) {
+		num++;
+		delta = 0;
+		s = GPOINTER_TO_UINT(iter->data);
+		if(s == janus_rtp_packet_status_smalldelta) {
+			/* Small delta = 1 byte */
+			delta = *data;
+			total--;
+			data++;
+		} else if(s == janus_rtp_packet_status_largeornegativedelta) {
+			/* Large or negative delta = 2 bytes */
+			if(total < 2)
+				break;
+			memcpy(&delta, data, sizeof(uint16_t));
+			delta = ntohs(delta);
+			total -= 2;
+			data += 2;
+		}
+		delta_us = delta*250;
+		/* Print summary */
+		JANUS_LOG(LOG_HUGE, "  [%02d][%"SCNu16"] %s (%"SCNu32"us)\n", num, base_seq+num-1,
+			janus_rtp_packet_status_description(s), delta_us);
+		iter = iter->next;
+	}
+	/* TODO Update the context with the feedback we got */
+	g_list_free(list);
+}
+
 /* Link quality estimate filter coefficient */
 #define LINK_QUALITY_FILTER_K 3.0
 
@@ -438,6 +555,9 @@ int janus_rtcp_fix_ssrc(janus_rtcp_context *ctx, char *packet, int len, int fixs
 						uint32_t *ssrc = (uint32_t *)rtcpfb->fci;
 						*ssrc = htonl(newssrcr);
 					}
+				} else if(fmt == 15) {	/* transport-cc */
+					/* If an RTCP context was provided, parse this transport-cc feedback */
+					janus_rtcp_incoming_transport_cc(ctx, rtcpfb, total);
 				} else {
 					JANUS_LOG(LOG_HUGE, "     #%d ??? -- RTPFB (205, fmt=%d)\n", pno, fmt);
 				}
@@ -1368,13 +1488,6 @@ int janus_rtcp_nacks(char *packet, int len, GSList *nacks) {
 	return words*4+4;
 }
 
-typedef enum janus_rtp_packet_status {
-	janus_rtp_packet_status_notreceived = 0,
-	janus_rtp_packet_status_smalldelta = 1,
-	janus_rtp_packet_status_largeornegativedelta = 2,
-	janus_rtp_packet_status_reserved = 3
-} janus_rtp_packet_status;
-
 int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssrc, guint32 media, guint8 feedback_packet_count, GQueue *transport_wide_cc_stats) {
 	if(packet == NULL || size < sizeof(janus_rtcp_header) || transport_wide_cc_stats == NULL || g_queue_is_empty(transport_wide_cc_stats))
 		return -1;
@@ -1401,11 +1514,11 @@ int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssr
 	/*
 		0                   1                   2                   3
 		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-	       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-	       |      base sequence number     |      packet status count      |
-	       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-	       |                 reference time                | fb pkt. count |
-	       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|      base sequence number     |      packet status count      |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+		|                 reference time                | fb pkt. count |
+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 	 */
 
 	/* The packet as unsigned */
@@ -1473,7 +1586,7 @@ int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssr
 			timestamp = stat->timestamp;
 		}
 
-		/* Check if all previoues ones were equal and this one the firt different */
+		/* Check if all previoues ones were equal and this one the first different */
 		if (all_same && last_status!=janus_rtp_packet_status_reserved && status!=last_status) {
 			/* How big was the same run */
 			if (g_queue_get_length(statuses)>7) {
@@ -1482,9 +1595,9 @@ int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssr
 				/*
 					0                   1
 					0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-				       |T| S |       Run Length        |
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					|T| S |       Run Length        |
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 					T = 0
 				 */
 				word = janus_push_bits(word, 1, 0);
@@ -1516,17 +1629,17 @@ int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssr
 		/* Store las status */
 		last_status = status;
 
-		/* Check if we can still be enquing for a run */
+		/* Check if we can still be enqueuing for a run */
 		if (!all_same) {
 			/* Check  */
 			if (!all_same && max_status==janus_rtp_packet_status_largeornegativedelta && g_queue_get_length(statuses)>6) {
 				guint32 word = 0;
 				/*
 					0                   1
 					0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-				       |T|S|        Symbols            |
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					|T|S|        Symbols            |
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 					T = 1
 					S = 1
 				 */
@@ -1570,11 +1683,11 @@ int janus_rtcp_transport_wide_cc_feedback(char *packet, size_t size, guint32 ssr
 				/*
 					0                   1
 					0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-				       |T|S|       symbol list         |
-				       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-					 T = 1
-					 S = 0
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					|T|S|       symbol list         |
+					+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+					T = 1
+					S = 0
 				 */
 				word = janus_push_bits(word, 1, 1);
 				word = janus_push_bits(word, 1, 0);

rtcp.h

@@ -276,6 +276,9 @@ typedef struct rtcp_context
 	double in_media_link_quality;
 	double out_link_quality;
 	double out_media_link_quality;
+
+	/* TODO Incoming transport-wide CC feedback*/
+
 } rtcp_context;
 typedef rtcp_context janus_rtcp_context;
 

rtp.c

@@ -303,14 +303,27 @@ int janus_rtp_header_extension_parse_transport_wide_cc(char *buf, int len, int i
 	if(ext == NULL)
 		return -2;
 	int val_len = (*ext & 0x0F) + 1;
-	if (val_len < 2 || val_len > len-(ext-buf)-1) {
+	if (val_len < 2 || val_len > len-(ext-buf)-1)
 		return -3;
-	}
 	memcpy(transSeqNum, ext+1, sizeof(uint16_t));
 	*transSeqNum = ntohs(*transSeqNum);
 	return 0;
 }
 
+int janus_rtp_header_extension_set_transport_wide_cc(char *buf, int len, int id, uint16_t transSeqNum) {
+	char *ext = NULL;
+	if(janus_rtp_header_extension_find(buf, len, id, NULL, NULL, &ext) < 0)
+		return -1;
+	if(ext == NULL)
+		return -2;
+	int val_len = (*ext & 0x0F) + 1;
+	if (val_len < 2 || val_len > len-(ext-buf)-1)
+		return -3;
+	transSeqNum = htons(transSeqNum);
+	memcpy(ext+1, &transSeqNum, sizeof(uint16_t));
+	return 0;
+}
+
 int janus_rtp_header_extension_replace_id(char *buf, int len, int id, int new_id) {
 	if(!buf || len < 12)
 		return -1;

rtp.h

@@ -208,10 +208,17 @@ int janus_rtp_header_extension_parse_framemarking(char *buf, int len, int id, ja
  * @param[in] buf The packet data
  * @param[in] len The packet data length in bytes
  * @param[in] id The extension ID to look for
- * @param[out] transSeqNum transport wide sequence number
+ * @param[out] transSeqNum Variable to read the transport wide sequence number in
  * @returns 0 if found, -1 otherwise */
-int janus_rtp_header_extension_parse_transport_wide_cc(char *buf, int len, int id,
-	uint16_t *transSeqNum);
+int janus_rtp_header_extension_parse_transport_wide_cc(char *buf, int len, int id, uint16_t *transSeqNum);
+
+/*! \brief Helper to set a transport wide sequence number (https://tools.ietf.org/html/draft-holmer-rmcat-transport-wide-cc-extensions-01)
+ * @param[in] buf The packet data
+ * @param[in] len The packet data length in bytes
+ * @param[in] id The extension ID to look for
+ * @param[out] transSeqNum Transport wide sequence number to set
+ * @returns 0 if found, -1 otherwise */
+int janus_rtp_header_extension_set_transport_wide_cc(char *buf, int len, int id, uint16_t transSeqNum);
 
 /*! \brief Helper to replace the ID of an RTP extension with a different one (e.g.,
  * to turn a repaired-rtp-stream-id into a rtp-stream-id after a successful rtx)