调整 addSSRCItem 函数 (#1224)

* update readme.

* refactor(sdp): update addSSRCItem.

* refactor(sdp): remove addSSRCItem.

* refactor(sdp): 调整逻辑，生成a=ssrc-group:FID字段

README.md

@@ -126,7 +126,7 @@
  你有三种方法使用ZLMediaKit，分别是：
 
  - 1、使用c api，作为sdk使用，请参考[这里](https://github.com/xia-chu/ZLMediaKit/tree/master/api/include).
- - 2、作为独立的流媒体服务器使用，不想做c/c++开发的，可以参考[restful api](https://github.com/xia-chu/ZLMediaKit/wiki/MediaServer%E6%94%AF%E6%8C%81%E7%9A%84HTTP-API)和[web hook](https://github.com/xia-chu/ZLMediaKit/wiki/MediaServer%E6%94%AF%E6%8C%81%E7%9A%84HTTP-HOOK-API).
+ - 2、作为独立的流媒体服务器使用，不想做c/c++开发的，可以参考 [restful api](https://github.com/xia-chu/ZLMediaKit/wiki/MediaServer支持的HTTP-API) 和 [web hook](https://github.com/xia-chu/ZLMediaKit/wiki/MediaServer支持的HTTP-HOOK-API ).
  - 3、如果想做c/c++开发，添加业务逻辑增加功能，可以参考这里的[测试程序](https://github.com/xia-chu/ZLMediaKit/tree/master/tests).
 
 ## Docker 镜像

webrtc/Sdp.cpp

@@ -1022,6 +1022,8 @@ string RtcSession::toRtspSdp() const{
     return sdp->toString();
 }
 
+void addSdpAttrSSRC(const RtcSSRC &rtp_ssrc, vector<SdpItem::Ptr> &items, uint32_t ssrc_num);
+
 RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
     RtcSessionSdp::Ptr ret = std::make_shared<RtcSessionSdp>();
     auto &sdp = *ret;
@@ -1126,51 +1128,15 @@ RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
                 }
             }
 
-            static auto addSSRCItem = [](const RtcSSRC &rtp_ssrc, vector<SdpItem::Ptr> &items) {
-                CHECK(!rtp_ssrc.empty());
-                auto ssrc_num = rtp_ssrc.ssrc;
-                for (auto i = 0; i < 2; ++i) {
-                    SdpAttrSSRC ssrc;
-                    ssrc.ssrc = ssrc_num;
-
-                    ssrc.attribute = "cname";
-                    ssrc.attribute_value = rtp_ssrc.cname;
-                    items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
-
-                    if (!rtp_ssrc.msid.empty()) {
-                        ssrc.attribute = "msid";
-                        ssrc.attribute_value = rtp_ssrc.msid;
-                        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
-                    }
-
-                    if (!rtp_ssrc.mslabel.empty()) {
-                        ssrc.attribute = "mslabel";
-                        ssrc.attribute_value = rtp_ssrc.mslabel;
-                        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
-                    }
-
-                    if (!rtp_ssrc.label.empty()) {
-                        ssrc.attribute = "label";
-                        ssrc.attribute_value = rtp_ssrc.label;
-                        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
-                    }
-                    if (rtp_ssrc.rtx_ssrc) {
-                        ssrc_num = rtp_ssrc.rtx_ssrc;
-                    } else {
-                        break;
-                    }
-                }
-            };
-
             {
                 for (auto &ssrc : m.rtp_rtx_ssrc) {
                     //添加a=ssrc字段
-                    addSSRCItem(ssrc, sdp_media.items);
+                    CHECK(!ssrc.empty());
-                }
+                    addSdpAttrSSRC(ssrc, sdp_media.items, ssrc.ssrc);
-
-                for (auto &ssrc : m.rtp_rtx_ssrc) {
-                    //生成a=ssrc-group:FID字段
                     if (ssrc.rtx_ssrc) {
+                        addSdpAttrSSRC(ssrc, sdp_media.items, ssrc.rtx_ssrc);
+
+                        //生成a=ssrc-group:FID字段
                         //有rtx ssrc
                         auto group = std::make_shared<SdpAttrSSRCGroup>();
                         group->type = "FID";
@@ -1219,6 +1185,33 @@ RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
     }
     return ret;
 }
+void addSdpAttrSSRC(const RtcSSRC &rtp_ssrc, vector<SdpItem::Ptr> &items, uint32_t ssrc_num) {
+    assert(ssrc_num);
+    SdpAttrSSRC ssrc;
+    ssrc.ssrc = ssrc_num;
+
+    ssrc.attribute = "cname";
+    ssrc.attribute_value = rtp_ssrc.cname;
+    items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
+
+    if (!rtp_ssrc.msid.empty()) {
+        ssrc.attribute = "msid";
+        ssrc.attribute_value = rtp_ssrc.msid;
+        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
+    }
+
+    if (!rtp_ssrc.mslabel.empty()) {
+        ssrc.attribute = "mslabel";
+        ssrc.attribute_value = rtp_ssrc.mslabel;
+        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
+    }
+
+    if (!rtp_ssrc.label.empty()) {
+        ssrc.attribute = "label";
+        ssrc.attribute_value = rtp_ssrc.label;
+        items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
+    }
+}
 
 string RtcSession::toString() const{
     return toRtcSessionSdp()->toString();