添加TWCC部分代码

src/Rtcp/RtcpFCI.cpp

@@ -167,5 +167,83 @@ string FCI_NACK::dumpString() const {
     return std::move(printer);
 }
 
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+RunLengthChunk::RunLengthChunk(SymbolStatus status, uint16_t run_length) {
+    type = 0;
+    symbol = (uint8_t)status & 0x03;
+    run_length_high = (run_length >> 8) & 0x1F;
+    run_length_low = run_length & 0xFF;
+}
+
+uint16_t RunLengthChunk::getRunLength() const {
+    CHECK(type == 0);
+    return run_length_high << 8 | run_length_low;
+}
+
+string RunLengthChunk::dumpString() const{
+    _StrPrinter printer;
+    printer << "run length chunk, symbol:" << (int)symbol << ", run length:" << getRunLength();
+    return std::move(printer);
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+StatusVecChunk::StatusVecChunk(const vector<SymbolStatus> &status) {
+    uint16_t value = 0;
+    type = 1;
+    if (status.size() == 14) {
+        symbol = 0;
+    } else if (status.size() == 7) {
+        symbol = 1;
+    } else {
+        //非法
+        CHECK(0);
+    }
+    int i = 13;
+    for (auto &item : status) {
+        CHECK(item <= SymbolStatus::reserved);
+        if (!symbol) {
+            CHECK(item <= SymbolStatus::small_delta);
+            value |= (int) item << i;
+            --i;
+        } else {
+            value |= (int) item << (i - 1);
+            i -= 2;
+        }
+    }
+    symbol_list_low = value & 0xFF;
+    symbol_list_high = (value >> 8 ) & 0x1F;
+}
+
+vector<SymbolStatus> StatusVecChunk::getSymbolList() const {
+    CHECK(type == 1);
+    vector<SymbolStatus> ret;
+    auto thiz = ntohs(*((uint16_t *) this));
+    if (symbol == 0) {
+        //s = 0 时，表示symbollist的每一个bit能表示一个数据包的到达状态
+        for (int i = 13; i >= 0; --i) {
+            SymbolStatus status = (SymbolStatus) ((bool) (thiz & (1 << i)));
+            ret.emplace_back(status);
+        }
+    } else {
+        //s = 1 时，表示symbollist每两个bit表示一个数据包的状态
+        for (int i = 12; i >= 0; i -= 2) {
+            SymbolStatus status = (SymbolStatus) ((thiz & (3 << i)) >> i);
+            ret.emplace_back(status);
+        }
+    }
+    return ret;
+}
+
+string StatusVecChunk::dumpString() const {
+    _StrPrinter printer;
+    printer << "status vector chunk, symbol:" << (int) symbol << ", symbol list:";
+    auto vec = getSymbolList();
+    for (auto &item : vec) {
+        printer << (int) item << " ";
+    }
+    return std::move(printer);
+}
 
 }//namespace mediakit

src/Rtcp/RtcpFCI.h

@@ -222,6 +222,7 @@ public:
 class FCI_NACK {
 public:
     static constexpr size_t kBitSize = 16;
+    static constexpr size_t kSize = 4;
 
     // The PID field is used to specify a lost packet.  The PID field
     //      refers to the RTP sequence number of the lost packet.
@@ -259,6 +260,8 @@ public:
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 class FCI_TMMBR {
 public:
+    static size_t constexpr kSize = 8;
+
     //SSRC (32 bits): The SSRC value of the media sender that is
     //              requested to obey the new maximum bit rate.
     uint32_t ssrc;
@@ -315,8 +318,92 @@ public:
 //       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //       |           recv delta          |  recv delta   | zero padding  |
 //       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+enum class SymbolStatus : uint8_t{
+    //Packet not received
+    not_received = 0,
+    //Packet received, small delta （所谓small detal是指能用一个字节表示的数值）
+    small_delta = 1,
+    // Packet received, large ornegative delta （large即是能用两个字节表示的数值）
+    large_delta = 2,
+    //Reserved
+    reserved = 3
+};
+
+class RunLengthChunk {
+public:
+    static size_t constexpr kSize = 2;
+    //       0                   1
+    //       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+    //      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    //      |T| S |       Run Length        |
+    //      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+#if __BYTE_ORDER == __BIG_ENDIAN
+    uint16_t type: 1;
+    uint16_t symbol: 2;
+    uint16_t run_length_high: 5;
+#else
+    // Run Length 高5位
+    uint16_t run_length_high: 5;
+    //参考SymbolStatus定义
+    uint16_t symbol: 2;
+    //固定为0
+    uint16_t type: 1;
+#endif
+    // Run Length 低8位
+    uint16_t run_length_low: 8;
+
+    //获取Run Length
+    uint16_t getRunLength() const;
+    //构造函数
+    RunLengthChunk(SymbolStatus status, uint16_t run_length);
+
+    string dumpString() const;
+} PACKED;
+
+class StatusVecChunk {
+public:
+    static size_t constexpr kSize = 2;
+    //       0                   1
+    //       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+    //      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    //      |T| S |       Run Length        |
+    //      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+#if __BYTE_ORDER == __BIG_ENDIAN
+    uint16_t type: 1;
+    uint16_t symbol: 1;
+    uint16_t symbol_list_high: 6;
+#else
+    // symbol_list 高6位
+    uint16_t symbol_list_high: 6;
+    //symbol_list中元素是1个还是2个bit
+    uint16_t symbol: 1;
+    //固定为1
+    uint16_t type: 1;
+#endif
+    // symbol_list 低8位
+    uint16_t symbol_list_low: 8;
+
+    //获取symbollist
+    vector<SymbolStatus> getSymbolList() const;
+    //构造函数
+    StatusVecChunk(const vector<SymbolStatus> &status);
+
+    string dumpString() const;
+} PACKED;
+
 class FCI_TWCC{
 public:
+    static size_t constexpr kSize = 12;
+
+    //base sequence number,基础序号,本次反馈的第一个包的序号;也就是RTP扩展头的序列号
+    uint16_t base_seq;
+    //packet status count, 包个数,本次反馈包含多少个包的状态;从基础序号开始算
+    uint16_t pkt_status_count;
+    //reference time,基准时间,绝对时间;计算该包中每个媒体包的到达时间都要基于这个基准时间计算
+    uint8_t ref_time[3];
+    //feedback packet count,反馈包号,本包是第几个transport-cc包，每次加1                          |
+    uint8_t fb_pkt_count;
 
 } PACKED;
 

tests/test_rtcp_fci.cpp

@@ -42,5 +42,28 @@ int main() {
         nack.net2Host();
         InfoL << nack.dumpString();
     }
+    {
+        RunLengthChunk chunk(SymbolStatus::large_delta, 8024);
+        InfoL << hexdump(&chunk, RunLengthChunk::kSize);
+        InfoL << chunk.dumpString();
+    }
+
+    auto lam = [](const initializer_list<int> &lst){
+        vector<SymbolStatus> ret;
+        for(auto &num : lst){
+            ret.emplace_back((SymbolStatus)num);
+        }
+        return ret;
+    };
+    {
+        StatusVecChunk chunk(lam({0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1}));
+        InfoL << hexdump(&chunk, StatusVecChunk::kSize);
+        InfoL << chunk.dumpString();
+    }
+    {
+        StatusVecChunk chunk(lam({0, 1, 2, 3, 0, 1, 2}));
+        InfoL << hexdump(&chunk, StatusVecChunk::kSize);
+        InfoL << chunk.dumpString();
+    }
     return 0;
 }