refactor: 梳理 rtx 处理逻辑

webrtc/WebRtcTransport.cpp

@@ -385,10 +385,10 @@ void WebRtcTransportImp::onStartWebRTC() {
         _ssrc_to_track[track->offer_ssrc_rtx] = track;
 
         //rtp pt --> MediaTrack
-        _pt_to_track.emplace(track->plan_rtp->pt, std::make_pair(false, track));
+        _pt_to_track.emplace(track->plan_rtp->pt, new WrappedRtpTrack(track, _twcc_ctx, *this));
         if (track->plan_rtx) {
             //rtx pt --> MediaTrack
-            _pt_to_track.emplace(track->plan_rtx->pt, std::make_pair(true, track));
+            _pt_to_track.emplace(track->plan_rtx->pt, new WrappedRtxTrack(track));
         }
         if (m_offer->type != TrackApplication) {
             //记录rtp ext类型与id的关系，方便接收或发送rtp时修改rtp ext id
@@ -691,28 +691,25 @@ void WebRtcTransportImp::onRtp(const char *buf, size_t len, uint64_t stamp_ms) {
         WarnL << "unknown rtp pt:" << (int)rtp->pt;
         return;
     }
-    bool is_rtx = it->second.first;
+    it->second->inputRtp(buf, len, stamp_ms, rtp);
+}
+
+void WrappedRtpTrack::inputRtp(const char *buf, size_t len, uint64_t stamp_ms, RtpHeader *rtp) {
     auto ssrc = ntohl(rtp->ssrc);
-    auto &track = it->second.second;
 
     //修改ext id至统一
     string rid;
     auto twcc_ext = track->rtp_ext_ctx->changeRtpExtId(rtp, true, &rid, RtpExtType::transport_cc);
-    if (twcc_ext && !is_rtx) {
+
+    if (twcc_ext) {
         _twcc_ctx.onRtp(ssrc, twcc_ext.getTransportCCSeq(), stamp_ms);
     }
 
     auto &ref = track->rtp_channel[rid];
     if (!ref) {
-        if (is_rtx) {
+        _transport.createRtpChannel(rid, ssrc, *track);
-            //再接收到对应的rtp前，丢弃rtx包
-            WarnL << "unknown rtx rtp, rid:" << rid << ", ssrc:" << ssrc << ", codec:" << track->plan_rtp->codec << ", seq:" << ntohs(rtp->seq);
-            return;
-        }
-        createRtpChannel(rid, ssrc, *track);
     }
 
-    if (!is_rtx) {
     //这是普通的rtp数据
 #if 0
     auto seq = ntohs(rtp->seq);
@@ -723,11 +720,22 @@ void WebRtcTransportImp::onRtp(const char *buf, size_t len, uint64_t stamp_ms) {
 #endif
     //解析并排序rtp
     ref->inputRtp(track->media->type, track->plan_rtp->sample_rate, (uint8_t *) buf, len, false);
+}
+
+void WrappedRtxTrack::inputRtp(const char *buf, size_t len, uint64_t stamp_ms, RtpHeader *rtp) {
+    //修改ext id至统一
+    string rid;
+    track->rtp_ext_ctx->changeRtpExtId(rtp, true, &rid, RtpExtType::transport_cc);
+
+    auto &ref = track->rtp_channel[rid];
+    if (!ref) {
+        //再接收到对应的rtp前，丢弃rtx包
+        WarnL << "unknown rtx rtp, rid:" << rid << ", ssrc:" << ntohl(rtp->ssrc) << ", codec:" << track->plan_rtp->codec << ", seq:" << ntohs(rtp->seq);
         return;
     }
 
     //这里是rtx重传包
-    //https://datatracker.ietf.org/doc/html/rfc4588#section-4
+    // https://datatracker.ietf.org/doc/html/rfc4588#section-4
     auto payload = rtp->getPayloadData();
     auto size = rtp->getPayloadSize(len);
     if (size < 2) {
@@ -736,7 +744,7 @@ void WebRtcTransportImp::onRtp(const char *buf, size_t len, uint64_t stamp_ms) {
 
     //前两个字节是原始的rtp的seq
     auto origin_seq = payload[0] << 8 | payload[1];
-    //rtx 转换为 rtp
+    // rtx 转换为 rtp
     rtp->pt = track->plan_rtp->pt;
     rtp->seq = htons(origin_seq);
     rtp->ssrc = htonl(ref->getSSRC());

webrtc/WebRtcTransport.h

@@ -189,6 +189,33 @@ public:
     std::shared_ptr<RtpChannel> getRtpChannel(uint32_t ssrc) const;
 };
 
+struct WrappedMediaTrack {
+    MediaTrack::Ptr track;
+    explicit WrappedMediaTrack(MediaTrack::Ptr ptr): track(ptr) {}
+    virtual ~WrappedMediaTrack() {}
+    virtual void inputRtp(const char *buf, size_t len, uint64_t stamp_ms, RtpHeader *rtp) = 0;
+};
+
+struct WrappedRtxTrack: public WrappedMediaTrack {
+    explicit WrappedRtxTrack(MediaTrack::Ptr ptr)
+        : WrappedMediaTrack(std::move(ptr)) {}
+    void inputRtp(const char *buf, size_t len, uint64_t stamp_ms, RtpHeader *rtp) override;
+};
+
+class WebRtcTransportImp;
+
+struct WrappedRtpTrack : public WrappedMediaTrack {
+    explicit WrappedRtpTrack(MediaTrack::Ptr ptr, TwccContext& twcc, WebRtcTransportImp& t)
+        : WrappedMediaTrack(std::move(ptr))
+        , _twcc_ctx(twcc)
+        , _transport(t) {}
+    TwccContext& _twcc_ctx;
+    WebRtcTransportImp& _transport;
+    void inputRtp(const char *buf, size_t len, uint64_t stamp_ms, RtpHeader *rtp) override;
+};
+
+
+
 class WebRtcTransportImp : public WebRtcTransport {
 public:
     using Ptr = std::shared_ptr<WebRtcTransportImp>;
@@ -202,6 +229,8 @@ public:
     bool canRecvRtp() const;
     void onSendRtp(const RtpPacket::Ptr &rtp, bool flush, bool rtx = false);
 
+    void createRtpChannel(const string &rid, uint32_t ssrc, MediaTrack &track);
+
 protected:
     WebRtcTransportImp(const EventPoller::Ptr &poller);
     void onStartWebRTC() override;
@@ -224,7 +253,7 @@ private:
     void onSortedRtp(MediaTrack &track, const string &rid, RtpPacket::Ptr rtp);
     void onSendNack(MediaTrack &track, const FCI_NACK &nack, uint32_t ssrc);
     void onSendTwcc(uint32_t ssrc, const string &twcc_fci);
-    void createRtpChannel(const string &rid, uint32_t ssrc, MediaTrack &track);
+
     void registerSelf();
     void unregisterSelf();
     void unrefSelf();
@@ -251,7 +280,7 @@ private:
     //根据rtcp的ssrc获取相关信息，收发rtp和rtx的ssrc都会记录
     unordered_map<uint32_t/*ssrc*/, MediaTrack::Ptr> _ssrc_to_track;
     //根据接收rtp的pt获取相关信息
-    unordered_map<uint8_t/*pt*/, std::pair<bool/*is rtx*/,MediaTrack::Ptr> > _pt_to_track;
+    unordered_map<uint8_t/*pt*/, std::unique_ptr<WrappedMediaTrack>> _pt_to_track;
 };
 
 class WebRtcTransportManager {