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..acc1bb83c5a0e448e030d42b98eab5d25315b0a1 100644
--- a/webrtc/modules/video_coding/frame_buffer2.cc
+++ b/webrtc/modules/video_coding/frame_buffer2.cc
@@ -93,7 +93,8 @@ FrameBuffer::ReturnReason FrameBuffer::NextFrame(
       if (continuous_end_it != frames_.end())
         ++continuous_end_it;
 
-      for (; frame_it != continuous_end_it; ++frame_it) {
+      for (; frame_it != continuous_end_it && frame_it != frames_.end();
+           ++frame_it) {
         if (!frame_it->second.continuous ||
             frame_it->second.num_missing_decodable > 0) {
           continue;
@@ -233,6 +234,17 @@ 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) {