From 146a48b0fabef7e74f2a2b62fb5cb45f9b393408 Mon Sep 17 00:00:00 2001
From: philipel <philipel@webrtc.org>
Date: Thu, 20 Apr 2017 04:04:38 -0700
Subject: [PATCH] Check if the order of frames becomes ambiguous if we were to
 insert the incoming frame, and if so, clear the FrameBuffer.

BUG=chromium:679306

Review-Url: https://codereview.webrtc.org/2830723002
Cr-Commit-Position: refs/heads/master@{#17785}
---
 webrtc/modules/video_coding/frame_buffer2.cc  | 14 +++++++++++++-
 .../video_coding/frame_buffer2_unittest.cc    | 19 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/webrtc/modules/video_coding/frame_buffer2.cc b/webrtc/modules/video_coding/frame_buffer2.cc
index fcd523820f..acc1bb83c5 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) {
diff --git a/webrtc/modules/video_coding/frame_buffer2_unittest.cc b/webrtc/modules/video_coding/frame_buffer2_unittest.cc
index b67d99376f..04ce5595a5 100644
--- a/webrtc/modules/video_coding/frame_buffer2_unittest.cc
+++ b/webrtc/modules/video_coding/frame_buffer2_unittest.cc
@@ -497,5 +497,24 @@ TEST_F(TestFrameBuffer2, StatsCallback) {
   CheckFrame(0, pid, 0);
 }
 
+TEST_F(TestFrameBuffer2, ForwardJumps) {
+  EXPECT_EQ(5453, InsertFrame(5453, 0, 1, false));
+  ExtractFrame();
+  EXPECT_EQ(5454, InsertFrame(5454, 0, 1, false, 5453));
+  ExtractFrame();
+  EXPECT_EQ(15670, InsertFrame(15670, 0, 1, false));
+  ExtractFrame();
+  EXPECT_EQ(29804, InsertFrame(29804, 0, 1, false));
+  ExtractFrame();
+  EXPECT_EQ(29805, InsertFrame(29805, 0, 1, false, 29804));
+  ExtractFrame();
+  EXPECT_EQ(29806, InsertFrame(29806, 0, 1, false, 29805));
+  ExtractFrame();
+  EXPECT_EQ(33819, InsertFrame(33819, 0, 1, false));
+  ExtractFrame();
+  EXPECT_EQ(41248, InsertFrame(41248, 0, 1, false));
+  ExtractFrame();
+}
+
 }  // namespace video_coding
 }  // namespace webrtc