BugFix: crash when FrameMerger::flush

In a lambda expression, temporary stack variables should not be captured; otherwise,
the variables may have become invalid when FrameMerger::flush is called.

src/Record/MPEG.cpp

@@ -55,7 +55,7 @@ bool MpegMuxer::inputFrame(const Frame::Ptr &frame) {
         case CodecH264:
         case CodecH265: {
             // 这里的代码逻辑是让SPS、PPS、IDR这些时间戳相同的帧打包到一起当做一个帧处理，
-            return track.merger.inputFrame(frame, [&](uint64_t dts, uint64_t pts, const Buffer::Ptr &buffer, bool have_idr) {
+            return track.merger.inputFrame(frame, [this, &track](uint64_t dts, uint64_t pts, const Buffer::Ptr &buffer, bool have_idr) {
                 _key_pos = have_idr;
                 // 取视频时间戳为TS的时间戳
                 _timestamp = dts;