Add API to set track id in msid

include/rtc/description.hpp

@@ -141,9 +141,9 @@ public:
 		void removeFormat(const string &fmt);
 
 		void addSSRC(uint32_t ssrc, std::optional<string> name,
-		             std::optional<string> msid = nullopt);
+					 std::optional<string> msid = nullopt, std::optional<string> trackID = nullopt);
 		void replaceSSRC(uint32_t oldSSRC, uint32_t ssrc, std::optional<string> name,
-		                 std::optional<string> msid = nullopt);
+						 std::optional<string> msid = nullopt, std::optional<string> trackID = nullopt);
 		bool hasSSRC(uint32_t ssrc);
 		std::vector<uint32_t> getSSRCs();
 

include/rtc/rtc.h

@@ -215,8 +215,9 @@ RTC_EXPORT int rtcGetTrackDescription(int tr, char *buffer, int size);
 /// @param _direction Direction
 /// @param _name Name (optional)
 /// @param _msid MSID (optional)
+/// @param _trackID Track ID used in MSID (optional) 
 /// @returns Track id
-RTC_EXPORT int rtcAddTrackEx(int pc, rtcCodec codec, int payloadType, uint32_t ssrc, const char *_mid, rtcDirection direction, const char *_name, const char *_msid);
+RTC_EXPORT int rtcAddTrackEx(int pc, rtcCodec codec, int payloadType, uint32_t ssrc, const char *_mid, rtcDirection direction, const char *_name, const char *_msid, const char *_trackID);
 
 /// Set H264PacketizationHandler for track
 /// @param tr Track id

src/capi.cpp

@@ -435,7 +435,7 @@ int rtcDeleteDataChannel(int dc) {
 
 #if RTC_ENABLE_MEDIA
 
-void setSSRC(Description::Media *description, uint32_t ssrc, const char *_name, const char *_msid) {
+void setSSRC(Description::Media *description, uint32_t ssrc, const char *_name, const char *_msid, const char *_trackID) {
 
 	optional<string> name = nullopt;
 	if (_name) {
@@ -447,11 +447,16 @@ void setSSRC(Description::Media *description, uint32_t ssrc, const char *_name,
 		msid = string(_msid);
 	}
 
-	description->addSSRC(ssrc, name, msid);
+	optional<string> trackID = nullopt;
+	if (_trackID) {
+		trackID = string(_trackID);
+	}
+
+	description->addSSRC(ssrc, name, msid, trackID);
 }
 
 int rtcAddTrackEx(int pc, rtcCodec codec, int payloadType, uint32_t ssrc, const char *_mid,
-                  rtcDirection _direction, const char *_name, const char *_msid) {
+				  rtcDirection _direction, const char *_name, const char *_msid, const char *_trackID) {
 	return WRAP({
 		auto peerConnection = getPeerConnection(pc);
 
@@ -516,7 +521,7 @@ int rtcAddTrackEx(int pc, rtcCodec codec, int payloadType, uint32_t ssrc, const
 			throw std::invalid_argument("Unexpected codec");
 		} else {
 			auto description = optDescription.value();
-			setSSRC(&description, ssrc, _name, _msid);
+			setSSRC(&description, ssrc, _name, _msid, _trackID);
 
 			int tr = emplaceTrack(peerConnection->addTrack(std::move(description)));
 			if (auto ptr = getUserPointer(pc)) {

src/description.cpp

@@ -525,20 +525,20 @@ Description::Entry::removeAttribute(std::vector<string>::iterator it) {
 }
 
 void Description::Media::addSSRC(uint32_t ssrc, std::optional<string> name,
-                                 std::optional<string> msid) {
+								 std::optional<string> msid, std::optional<string> trackID) {
 	if (name)
 		mAttributes.emplace_back("ssrc:" + std::to_string(ssrc) + " cname:" + *name);
 	else
 		mAttributes.emplace_back("ssrc:" + std::to_string(ssrc));
 
 	if (msid)
-		mAttributes.emplace_back("ssrc:" + std::to_string(ssrc) + " msid:" + *msid + " " + *msid);
+		mAttributes.emplace_back("ssrc:" + std::to_string(ssrc) + " msid:" + *msid + " " + trackID.value_or(*msid));
 
 	mSsrcs.emplace_back(ssrc);
 }
 
 void Description::Media::replaceSSRC(uint32_t oldSSRC, uint32_t ssrc, std::optional<string> name,
-                                     std::optional<string> msid) {
+									 std::optional<string> msid, std::optional<string> trackID) {
 	auto it = mAttributes.begin();
 	while (it != mAttributes.end()) {
 		if (it->find("ssrc:" + std::to_string(oldSSRC)) == 0) {
@@ -546,7 +546,7 @@ void Description::Media::replaceSSRC(uint32_t oldSSRC, uint32_t ssrc, std::optio
 		} else
 			it++;
 	}
-	addSSRC(ssrc, std::move(name), std::move(msid));
+	addSSRC(ssrc, std::move(name), std::move(msid), std::move(trackID));
 }
 
 void Description::Media::removeSSRC(uint32_t oldSSRC) {