feat: add broadcast event for player count change (#3562)

src/Common/config.h

@@ -124,6 +124,10 @@ extern const std::string kBroadcastRtcSctpSend;
 extern const std::string kBroadcastRtcSctpReceived;
 #define BroadcastRtcSctpReceivedArgs WebRtcTransport& sender, uint16_t &streamId, uint32_t &ppid, const uint8_t *&msg, size_t &len
 
+// 观看人数变化广播
+extern const std::string kBroadcastPlayerCountChanged;
+#define BroadcastPlayerCountChangedArgs const MediaTuple& args, const int& count
+
 #define ReloadConfigTag ((void *)(0xFF))
 #define RELOAD_KEY(arg, key)                                                                                           \
     do {                                                                                                               \
@@ -196,6 +200,8 @@ extern const std::string kWaitTrackReadyMS;
 extern const std::string kWaitAddTrackMS;
 // 如果track未就绪，我们先缓存帧数据，但是有最大个数限制(100帧时大约4秒)，防止内存溢出
 extern const std::string kUnreadyFrameCache;
+// 是否启用观看人数变化事件广播，置1则启用，置0则关闭
+extern const std::string kBroadcastPlayerCountChanged;
 } // namespace General
 
 namespace Protocol {