Unit test for media packet reordering in ForwardErrorCorrection.

webrtc/modules/rtp_rtcp/source/rtp_fec_unittest.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 183 matching lines @@
   EXPECT_EQ(0,
             fec_->DecodeFec(&received_packet_list_, &recovered_packet_list_));
 
   // Expect that no decoding is done to get missing packet (seq#0) of second
   // frame, using old FEC packet (seq#2) from first (old) frame. So number of
   // recovered packets is 2, and not equal to number of media packets (=3).
   EXPECT_EQ(2, static_cast<int>(recovered_packet_list_.size()));
   EXPECT_TRUE(recovered_packet_list_.size() != media_packet_list_.size());
 }
 
-// Verify we can still recovery frame if sequence number wrap occurs within
+// Verify we can still recover frame if sequence number wrap occurs within
 // the frame and FEC packet following wrap is received after media packets.
 TEST_F(RtpFecTest, FecRecoveryWithSeqNumGapOneFrameRecovery) {
   const int kNumImportantPackets = 0;
   const bool kUseUnequalProtection = false;
   uint8_t kProtectionFactor = 20;
 
   // One frame, with sequence number wrap in media packets.
   //         -----Frame 1----
   //  #65534(media) #65535(media) #0(media) #1(FEC).
   fec_seq_num_ = ConstructMediaPacketsSeqNum(3, 65534);
@@ skipping 59 matching lines @@
 
   // The two FEC packets are received and should allow for complete recovery,
   // but because of the wrap the second FEC packet will be discarded, and only
   // one media packet is recoverable. So exepct 2 media packets on recovered
   // list and no complete recovery.
   EXPECT_EQ(2, static_cast<int>(recovered_packet_list_.size()));
   EXPECT_TRUE(recovered_packet_list_.size() != media_packet_list_.size());
   EXPECT_FALSE(IsRecoveryComplete());
 }
 
-// Verify we can still recovery frame if FEC is received before media packets.
+// Verify we can still recover frame if media packets are reordered.
+TEST_F(RtpFecTest, FecRecoveryWithMediaReordering) {
+  const int kNumImportantPackets = 0;

[danilchap, 2016/07/01 18:55:08]

might want change to constexpr, but may leave as const for local consistency.

[brandtr, 2016/07/04 13:56:07]

Done.

+  const bool kUseUnequalProtection = false;
+  uint8_t kProtectionFactor = 20;

[danilchap, 2016/07/01 18:55:08]

const

[brandtr, 2016/07/04 13:56:07]

Done.

+
+  // One frame: 3 media packets, 1 FEC packet.
+  //         -----Frame 1----
+  //  #0(media) #1(media) #2(media) #3(FEC).
+  fec_seq_num_ = ConstructMediaPacketsSeqNum(3, 0);
+
+  EXPECT_EQ(0, fec_->GenerateFec(media_packet_list_, kProtectionFactor,
+                                 kNumImportantPackets, kUseUnequalProtection,
+                                 webrtc::kFecMaskBursty, &fec_packet_list_));
+
+  // Expect 1 FEC packet.
+  EXPECT_EQ(1, static_cast<int>(fec_packet_list_.size()));

[danilchap, 2016/07/01 18:55:08]

EXPECT_EQ(1u, fec_packet_list_.size()); is cleaner.

[brandtr, 2016/07/04 13:56:07]

Done.

+
+  // Lose one media packet (seq# 1).
+  memset(media_loss_mask_, 0, sizeof(media_loss_mask_));
+  memset(fec_loss_mask_, 0, sizeof(fec_loss_mask_));
+  media_loss_mask_[1] = 1;
+  NetworkReceivedPackets();
+
+  // Reorder received media packets.
+  auto it0 = received_packet_list_.begin();
+  auto it2 = received_packet_list_.begin(); it2++;

[danilchap, 2016/07/01 18:55:08]

do not keep two commands on one line

[brandtr, 2016/07/04 13:56:07]

Done.

+  std::swap(*it0, *it2);
+
+  EXPECT_EQ(0,
+            fec_->DecodeFec(&received_packet_list_, &recovered_packet_list_));
+
+  // Expect 3 media packets in recovered list, and complete recovery.
+  EXPECT_EQ(3, static_cast<int>(recovered_packet_list_.size()));

[danilchap, 2016/07/01 18:55:08]

EXPECT_EQ(3u, ...)

[brandtr, 2016/07/04 13:56:07]

Done.

+  EXPECT_TRUE(IsRecoveryComplete());
+}
+
+// Verify we can still recover frame if FEC is received before media packets.
 TEST_F(RtpFecTest, FecRecoveryWithFecOutOfOrder) {
   const int kNumImportantPackets = 0;
   const bool kUseUnequalProtection = false;
   uint8_t kProtectionFactor = 20;
 
   // One frame: 3 media packets, 1 FEC packet.
   //         -----Frame 1----
   //  #0(media) #1(media) #2(media) #3(FEC).
   fec_seq_num_ = ConstructMediaPacketsSeqNum(3, 0);
 
@@ skipping 619 matching lines @@
                                         PacketList* dst, int N) {
   RTC_DCHECK_GT(N, 0);
   int i = 0;
   for (auto& packet : src) {
     if (i % N == 0) {
       dst->emplace_back(new ForwardErrorCorrection::Packet(*packet));
     }
     ++i;
   }
 }