实现音频转码，有两种实现方式：

- 基于MultiMediaSourceMuxer：基于多流实现，不能实现无人观看不转码 - 基于RtmpMuxer和RtcMuxer来实现：性能较好，能实现无人观看不转码
mtdxc · Jan 17, 2024 · 3d6cfdf · 3d6cfdf
1 parent 0347342
commit 3d6cfdf
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Showing 3 changed files with 59 additions and 3 deletions.
diff --git a/src/Common/MultiMediaSourceMuxer.cpp b/src/Common/MultiMediaSourceMuxer.cpp
@@ -494,10 +494,27 @@ bool MultiMediaSourceMuxer::onTrackReady(const Track::Ptr &track) {
 
     bool ret = false;
     if (_rtmp) {
-        ret = _rtmp->addTrack(track) ? true : ret;
+        /* 利用多音频流来实现转码，这样也行，但无法控制按需转码
+        if (track->getCodecId() == CodecOpus) {
+            GET_CONFIG(int, bitrate, General::kAacBitrate);
+            link(track->getTransodeTrack(CodecAAC, 44100, 1, bitrate));
+        } 
+        else
+        */
+        {
+            ret = _rtmp->addTrack(track) ? true : ret;
+        }
     }
     if (_rtc) {
-        ret = _rtc->addTrack(track) ? true : ret;
+        /* 利用多音频流来实现转码，这样也行，但无法控制按需转码
+        if (track->getCodecId() == CodecAAC) {
+            GET_CONFIG(int, bitrate, General::kOpusBitrate);
+            link(track->getTransodeTrack(CodecOpus, 48000, 1, bitrate));
+        } 
+        else*/ 
+        {
+            ret = _rtc->addTrack(track) ? true : ret;
+        }
     }
     if (_rtsp) {
         ret = _rtsp->addTrack(track) ? true : ret;
@@ -521,7 +538,7 @@ bool MultiMediaSourceMuxer::onTrackReady(const Track::Ptr &track) {
 }
 
 void MultiMediaSourceMuxer::onAllTrackReady() {
-    CHECK(!_create_in_poller || getOwnerPoller(MediaSource::NullMediaSource())->isCurrentThread());
+    //CHECK(!_create_in_poller || getOwnerPoller(MediaSource::NullMediaSource())->isCurrentThread());
 
     if (_option.paced_sender_ms) {
         std::weak_ptr<MultiMediaSourceMuxer> weak_self = shared_from_this();

diff --git a/src/Rtmp/RtmpMediaSourceMuxer.h b/src/Rtmp/RtmpMediaSourceMuxer.h
@@ -50,11 +50,27 @@ class RtmpMediaSourceMuxer final : public RtmpMuxer, public MediaSourceEventInte
         _media_src->setMetaData(getMetadata());
     }
 
+    bool addTrack(const Track::Ptr &track) override {
+        auto t = track;
+        if (_option.audio_transcode && track->getCodecId() == CodecOpus) {
+            GET_CONFIG(int, bitrate, General::kAacBitrate);
+            _trans = track->getTransodeTrack(CodecAAC, 44100, 1, bitrate);
+            if (_trans) t = _trans;
+        }
+        return RtmpMuxer::addTrack(t);
+    }
+
     void onReaderChanged(MediaSource &sender, int size) override {
         _enabled = _option.rtmp_demand ? size : true;
         if (!size && _option.rtmp_demand) {
             _clear_cache = true;
         }
+        if (_trans) {
+            if (size)
+                _trans->addDelegate(shared_from_this());
+            else
+                _trans->delDelegate(this);
+        }
         MediaSourceEventInterceptor::onReaderChanged(sender, size);
     }
 
@@ -75,6 +91,7 @@ class RtmpMediaSourceMuxer final : public RtmpMuxer, public MediaSourceEventInte
     }
 
 private:
+    Track::Ptr _trans;
     bool _enabled = true;
     bool _clear_cache = false;
     ProtocolOption _option;

diff --git a/webrtc/RtcMediaSource.h b/webrtc/RtcMediaSource.h
@@ -30,6 +30,28 @@ class RtcMediaSourceMuxer : public RtspMediaSourceMuxer {
     RtcMediaSourceMuxer(const MediaTuple &tuple, const ProtocolOption &option, const TitleSdp::Ptr &title = nullptr)
         : RtspMediaSourceMuxer(tuple, option, title, RTC_SCHEMA) {
     }
+
+    bool addTrack(const Track::Ptr &track) override {
+        auto t = track;
+        if (_option.audio_transcode && track->getCodecId() == CodecAAC) {
+            GET_CONFIG(int, bitrate, General::kOpusBitrate);
+            _trans = track->getTransodeTrack(CodecOpus, 48000, 1, bitrate);
+            if (_trans) t = _trans;
+        }
+        return RtspMuxer::addTrack(t);
+    }
+
+    void onReaderChanged(MediaSource &sender, int size) override {
+        RtspMediaSourceMuxer::onReaderChanged(sender, size);
+        if (_trans) {
+            if (size)
+                _trans->addDelegate(shared_from_this());
+            else
+                _trans->delDelegate(this);
+        }
+    }
+protected:
+    Track::Ptr _trans;
 };
 
 }