Check if the order of frames becomes ambiguous by inserting a new frame, and if so, clear the Frame…

webrtc/modules/video_coding/frame_buffer2.cc

Index: webrtc/modules/video_coding/frame_buffer2.cc
diff --git a/webrtc/modules/video_coding/frame_buffer2.cc b/webrtc/modules/video_coding/frame_buffer2.cc
index fcd523820f0ef7825b7edaacb63b7e33460e8d2c..c4e1aec834f719eed2bd2a9086f44ed891094319 100644
--- a/webrtc/modules/video_coding/frame_buffer2.cc
+++ b/webrtc/modules/video_coding/frame_buffer2.cc
@@ -233,6 +233,17 @@ int FrameBuffer::InsertFrame(std::unique_ptr<FrameObject> frame) {
     }
   }
 
+  // Test if inserting this frame would cause the order of the frames to become
+  // ambiguous (covering more than half the interval of 2^16). This can happen
+  // when the picture id make large jumps mid stream.
+  if (!frames_.empty() &&
+      key < frames_.begin()->first &&
+      frames_.rbegin()->first < key) {
+    LOG(LS_WARNING) << "A jump in picture id was detected, clearing buffer.";
+    ClearFramesAndHistory();
+    last_continuous_picture_id = -1;
+  }
+
   auto info = frames_.insert(std::make_pair(key, FrameInfo())).first;
 
   if (info->second.frame) {