修复首帧不是I帧 导致花屏的问题

src/MediaFile/MP4Muxer.cpp

@@ -79,6 +79,14 @@ void MP4Muxer::onTrackFrame(const Frame::Ptr &frame) {
         return;
     }
 
+    if(frame->getTrackType() == TrackVideo){
+        if(!_started && !frame->keyFrame()){
+            //第一帧必须是I帧，防止花屏
+            return;
+        }
+        _started = true;
+    }
+
     int with_nalu_size ;
     switch (frame->getCodecId()){
         case CodecH264:

src/MediaFile/MP4Muxer.h

@@ -80,6 +80,7 @@ private:
         uint32_t start_pts = 0;
     };
     map<CodecId,track_info> _codec_to_trackid;
+    bool _started = false;
 };
 
 

src/MediaFile/Mp4Maker.cpp

@@ -89,10 +89,8 @@ void Mp4Maker::createFile() {
 	try {
 		_muxer = std::make_shared<MP4MuxerFile>(strFileTmp.data());
 		for(auto &track :_tracks){
-			if(track){
-				//添加track
-				_muxer->addTrack(track);
-			}
+            //添加track
+            _muxer->addTrack(track);
 		}
 		_strFileTmp = strFileTmp;
 		_strFile = strFile;