Add xr targetbitrate process and update js demo sdk (ZLMediaKit#4031)

rtc 增加对于rtcp xr target bitrate 的解析，参照
https://webrtc.googlesource.com/src/+/refs/heads/main/modules/rtp_rtcp/source/rtcp_packet/target_bitrate.cc

zlmrtcclient.js 更新，修复推屏幕流失败的问题

src/Rtcp/Rtcp.cpp

@@ -209,8 +209,13 @@ void RtcpHeader::net2Host(size_t len) {
                 RtcpXRDLRR *dlrr = (RtcpXRDLRR *)this;
                 dlrr->net2Host(len);
                 TraceL << dlrr->dumpString();
+            } else if (xr->bt == 42){
+                //当有浏览器将屏幕推流到服务器时会发生这个, 暂时没发现什么作用，先解析出来，不做处理
+                RtcpXRTargetBitrate* tb = (RtcpXRTargetBitrate *)this;
+                tb->net2Host(len);
+                //TraceL << tb->dumpString();
             } else {
-                throw std::runtime_error(StrPrinter << "rtcp xr bt " << xr->bt << " not support");
+                throw std::runtime_error(StrPrinter << "rtcp xr bt " << (int)xr->bt << " not support");
             }
             break;
         }
@@ -796,6 +801,71 @@ std::shared_ptr<RtcpXRDLRR> RtcpXRDLRR::create(size_t item_count) {
     return std::shared_ptr<RtcpXRDLRR>(ptr, [](RtcpXRDLRR *ptr) { delete[](char *) ptr; });
 }
 
+////////////////////////////////////
+string RtcpXRTargetBitrateItem::dumpString() const {
+    _StrPrinter printer;
+
+    printer << "Spatial Layer :" << spatial_layer << "\r\n";
+    printer << "Temporal Layer :" << temporal_layer << "\r\n";
+    printer << "Target Bitrate: " << target_bitrate << "\r\n";
+
+    return std::move(printer);
+}
+
+void RtcpXRTargetBitrateItem::net2Host() {
+
+    target_bitrate = ntohl(target_bitrate) >> 8;
+}
+
+std::vector<RtcpXRTargetBitrateItem *> RtcpXRTargetBitrate::getItemList() {
+    auto count = block_length;
+    RtcpXRTargetBitrateItem *ptr = &items;
+    vector<RtcpXRTargetBitrateItem *> ret;
+    for (int i = 0; i < (int)count; ++i) {
+        ret.emplace_back(ptr);
+        ++ptr;
+    }
+    return ret;
+}
+string RtcpXRTargetBitrate::dumpString() const {
+    _StrPrinter printer;
+    printer << RtcpHeader::dumpHeader();
+    printer << "ssrc :" << ssrc << "\r\n";
+    printer << "bt :" << (int)bt << "\r\n";
+    printer << "block_length : " << block_length << "\r\n";
+    auto items_list = ((RtcpXRTargetBitrate *)this)->getItemList();
+    auto i = 0;
+    for (auto &item : items_list) {
+        printer << "---- item:" << i++ << " ----\r\n";
+        printer << item->dumpString();
+    }
+    return std::move(printer);
+}
+
+void RtcpXRTargetBitrate::net2Host(size_t size) {
+    static const size_t kMinSize = sizeof(RtcpHeader);
+    CHECK_MIN_SIZE(size, kMinSize);
+
+    ssrc = ntohl(ssrc);
+    block_length = ntohs(block_length);
+
+    auto count = block_length;
+    for (int i = 0; i < (int)count; ++i) {
+        RtcpXRTargetBitrateItem *ptr = &items;
+        ptr->net2Host();
+        ptr++;
+    }
+}
+
+std::shared_ptr<RtcpXRTargetBitrate> RtcpXRTargetBitrate::create(size_t item_count) {
+    auto real_size = sizeof(RtcpXRTargetBitrate) - sizeof(RtcpXRTargetBitrateItem) + item_count * sizeof(RtcpXRTargetBitrateItem);
+    auto bytes = alignSize(real_size);
+    auto ptr = (RtcpXRTargetBitrate *)new char[bytes];
+    setupHeader(ptr, RtcpType::RTCP_XR, 0, bytes);
+    setupPadding(ptr, bytes - real_size);
+    return std::shared_ptr<RtcpXRTargetBitrate>(ptr, [](RtcpXRTargetBitrate *ptr) { delete[](char *) ptr; });
+}
+
 #if 0
 #include "Util/onceToken.h"
 

src/Rtcp/Rtcp.h

@@ -772,7 +772,6 @@ class RtcpXRDLRRReportItem {
 
     /**
      * 网络字节序转换为主机字节序
-     * @param size 字节长度，防止内存越界
      */
     void net2Host();
 };
@@ -814,6 +813,105 @@ class RtcpXRDLRR : public RtcpHeader {
 
 };
 
+//  RFC 4585: Feedback format.
+//
+//  Common packet format:
+//
+//   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
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |     BT=42     |   reserved    |         block length          |
+//  +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+//
+//  Target bitrate item (repeat as many times as necessary).
+//
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |   S   |   T   |                Target Bitrate                 |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  :  ...                                                          :
+//
+//  Spatial Layer (S): 4 bits
+//    Indicates which temporal layer this bitrate concerns.
+//
+//  Temporal Layer (T): 4 bits
+//    Indicates which temporal layer this bitrate concerns.
+//
+//  Target Bitrate: 24 bits
+//    The encoder target bitrate for this layer, in kbps.
+//
+//  As an example of how S and T are intended to be used, VP8 simulcast will
+//  use a separate TargetBitrate message per stream, since they are transmitted
+//  on separate SSRCs, with temporal layers grouped by stream.
+//  If VP9 SVC is used, there will be only one SSRC, so each spatial and
+//  temporal layer combo used shall be specified in the TargetBitrate packet.
+class RtcpXRTargetBitrateItem {
+public:
+    friend class RtcpXRTargetBitrate;
+#if __BYTE_ORDER == __BIG_ENDIAN
+    // Indicates which temporal layer this bitrate concerns.
+    uint32_t spatial_layer : 4;
+    // Indicates which temporal layer this bitrate concerns.
+    uint32_t temporal_layer : 4;
+#else
+    // Indicates which temporal layer this bitrate concerns.
+    uint32_t temporal_layer : 4;
+    // Indicates which temporal layer this bitrate concerns.
+    uint32_t spatial_layer : 4;
+#endif
+    //The encoder target bitrate for this layer, in kbps.
+    uint32_t target_bitrate : 24;
+
+private:
+    /**
+     * 打印字段详情
+     * 使用net2Host转换成主机字节序后才可使用此函数
+     */
+    std::string dumpString() const;
+
+    /**
+     * 网络字节序转换为主机字节序
+     */
+    void net2Host();
+};
+
+
+class RtcpXRTargetBitrate : public RtcpHeader {
+public:
+    friend class RtcpHeader;
+    uint32_t ssrc;
+    uint8_t bt;
+    uint8_t reserved;
+    uint16_t block_length;
+    RtcpXRTargetBitrateItem items;
+
+    /**
+     * 创建RtcpXRTargetBitrate包，只赋值了RtcpHeader部分(网络字节序)
+     * @param item_count RtcpXRTargetBitrateItem对象个数
+     * @return RtcpXRTargetBitrate包
+     */
+    static std::shared_ptr<RtcpXRTargetBitrate> create(size_t item_count);
+
+    /**
+     * 获取RtcpXRTargetBitrateItem对象指针列表
+     * 使用net2Host转换成主机字节序后才可使用此函数
+     */
+    std::vector<RtcpXRTargetBitrateItem *> getItemList();
+
+private:
+    /**
+     * 打印字段详情
+     * 使用net2Host转换成主机字节序后才可使用此函数
+     */
+    std::string dumpString() const;
+
+    /**
+     * 网络字节序转换为主机字节序
+     * @param size 字节长度，防止内存越界
+     */
+    void net2Host(size_t size);
+
+};
+
 #pragma pack(pop)
 
 } // namespace mediakit