From 86b92e05f9b64a98fdf1702ee2acec9ec6b1e95d Mon Sep 17 00:00:00 2001
From: philipel <philipel@webrtc.org>
Date: Mon, 24 Oct 2016 07:11:53 -0700
Subject: [PATCH] Drop VP8 frames older than the last sync frame in the
 RtpFrameReferenceFinder.

BUG=webrtc:5514

Review-Url: https://codereview.webrtc.org/2392313002
Cr-Commit-Position: refs/heads/master@{#14745}
---
 .../video_coding/rtp_frame_reference_finder.cc       | 10 ++++++++++
 .../rtp_frame_reference_finder_unittest.cc           | 12 ++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/webrtc/modules/video_coding/rtp_frame_reference_finder.cc b/webrtc/modules/video_coding/rtp_frame_reference_finder.cc
index d687a99924..a64518a41e 100644
--- a/webrtc/modules/video_coding/rtp_frame_reference_finder.cc
+++ b/webrtc/modules/video_coding/rtp_frame_reference_finder.cc
@@ -298,6 +298,14 @@ void RtpFrameReferenceFinder::ManageFrameVp8(
       return;
     }
 
+    // If the last frame on this layer is ahead of this frame it means that
+    // a layer sync frame has been received after this frame for the same
+    // base layer frame, drop this frame.
+    if (AheadOf<uint16_t, kPicIdLength>(layer_info_it->second[layer],
+                                        frame->picture_id)) {
+      return;
+    }
+
     // If we have not yet received a frame between this frame and the referenced
     // frame then we have to wait for that frame to be completed first.
     auto not_received_frame_it =
@@ -309,6 +317,8 @@ void RtpFrameReferenceFinder::ManageFrameVp8(
       return;
     }
 
+    RTC_DCHECK((AheadOf<uint16_t, kPicIdLength>(frame->picture_id,
+                                               layer_info_it->second[layer])));
     ++frame->num_references;
     frame->references[layer] = layer_info_it->second[layer];
   }
diff --git a/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc b/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
index 5fcb4425aa..5fa5ac843b 100644
--- a/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
+++ b/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
@@ -597,6 +597,18 @@ TEST_F(TestRtpFrameReferenceFinder, Vp8LayerSync) {
   CheckReferencesVp8(pid + 7, pid + 6, pid + 5);
 }
 
+TEST_F(TestRtpFrameReferenceFinder, Vp8Tl1SyncFrameAfterTl1Frame) {
+  InsertVp8(1000, 1000, true, 1, 0, 247, true);
+  InsertVp8(1001, 1001, false, 3, 0, 248, false);
+  InsertVp8(1002, 1002, false, 4, 1, 248, false);  // Will be dropped
+  InsertVp8(1003, 1003, false, 5, 1, 248, true);   // due to this frame.
+
+  ASSERT_EQ(3UL, frames_from_callback_.size());
+  CheckReferencesVp8(1);
+  CheckReferencesVp8(3, 1);
+  CheckReferencesVp8(5, 3);
+}
+
 TEST_F(TestRtpFrameReferenceFinder, Vp9GofInsertOneFrame) {
   uint16_t pid = Rand();
   uint16_t sn = Rand();