初步添加twcc rtcp发送逻辑

webrtc/TwccContext.cpp

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2021 The ZLMediaKit project authors. All Rights Reserved.
+ *
+ * This file is part of ZLMediaKit(https://github.com/xia-chu/ZLMediaKit).
+ *
+ * Use of this source code is governed by MIT license that can be found in the
+ * LICENSE file in the root of the source tree. All contributing project authors
+ * may be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "TwccContext.h"
+
+enum class ExtSeqStatus : int {
+    normal = 0,
+    looped,
+    jumped,
+};
+
+void TwccContext::onRtp(uint16_t twcc_ext_seq) {
+    switch ((ExtSeqStatus) checkSeqStatus(twcc_ext_seq)) {
+        case ExtSeqStatus::jumped: /*回环后，收到回环前的大ext seq包,过滤掉*/ return;
+        case ExtSeqStatus::looped: /*回环，触发发送twcc rtcp*/ onSendTwcc(); break;
+        case ExtSeqStatus::normal: break;
+        default: /*不可达*/assert(0); break;
+    }
+
+    auto result = _rtp_recv_status.emplace(twcc_ext_seq, _ticker.createdTime());
+    if (!result.second) {
+        WarnL << "recv same twcc ext seq:" << twcc_ext_seq;
+        return;
+    }
+
+    _max_stamp = result.first->second;
+    if (!_min_stamp) {
+        _min_stamp = _max_stamp;
+    }
+
+    if (checkIfNeedSendTwcc()) {
+        //其他匹配条件立即发送twcc
+        onSendTwcc();
+    }
+}
+
+bool TwccContext::checkIfNeedSendTwcc() const {
+    auto size = _rtp_recv_status.size();
+    if (!size) {
+        return false;
+    }
+    if (size >= kMaxSeqDelta) {
+        return true;
+    }
+    auto delta_ms = _max_stamp - _min_stamp;
+    if (delta_ms >= kMaxTimeDelta) {
+        return true;
+    }
+    return false;
+}
+
+int TwccContext::checkSeqStatus(uint16_t twcc_ext_seq) const {
+    if (_rtp_recv_status.empty()) {
+        return (int) ExtSeqStatus::normal;
+    }
+    auto max = _rtp_recv_status.rbegin()->first;
+    if (max > 0xFF00 && twcc_ext_seq < 0xFF) {
+        //发生回环了
+        TraceL << "rtp twcc ext seq looped:" << max << " -> " << twcc_ext_seq;
+        return (int) ExtSeqStatus::looped;
+    }
+    if (twcc_ext_seq - max > 0xFFFF / 2) {
+        TraceL << "rtp twcc ext seq jumped:" << max << " -> " << twcc_ext_seq;
+        return (int) ExtSeqStatus::jumped;
+    }
+    return (int) ExtSeqStatus::normal;
+}
+
+void TwccContext::onSendTwcc() {
+    auto max = _rtp_recv_status.rbegin()->first;
+    auto begin = _rtp_recv_status.begin();
+    auto min = begin->first;
+    auto ref_time = begin->second;
+    DebugL << "base_seq:" << min << ",pkt_status_count:" << max + 1 - min << ",ref time:" << ref_time / 64
+           << ", fb count:" << (int) (_twcc_pkt_count++);
+    for (auto i = min; i <= max; ++i) {
+        auto it = _rtp_recv_status.find(i);
+        if (it == _rtp_recv_status.end()) {
+            DebugL << "rtp seq:" << i << ",packet status:" << 0 /*not recved*/ << ",delta_ms:" << 0;
+        } else {
+            auto delta_ms = it->second - ref_time;
+            DebugL << "rtp seq:" << i << ",packet status:" << 1 /*recved*/ << ",delta_ms:" << delta_ms;
+        }
+    }
+    clearStatus();
+}
+
+void TwccContext::clearStatus() {
+    _rtp_recv_status.clear();
+    _min_stamp = 0;
+}