Added RTCMediaStreamTrackStats.concealmentEvents

The number of concealment events. This counter increases every time a concealed sample is
synthesized after a non-concealed sample. That is, multiple consecutive concealed samples
will increase the concealedSamples count multiple times but is a single concealment event.

Bug: webrtc:8246
Change-Id: I7ef404edab765218b1f11e3128072c5391e83049
Reviewed-on: https://webrtc-review.googlesource.com/1221
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19881}

modules/audio_coding/neteq/include/neteq.h

@@ -61,13 +61,11 @@ struct NetEqNetworkStatistics {
 // NetEq statistics that persist over the lifetime of the class.
 // These metrics are never reset.
 struct NetEqLifetimeStatistics {
-  // Total number of audio samples received, including synthesized samples.
-  // https://w3c.github.io/webrtc-stats/#dom-rtcmediastreamtrackstats-totalsamplesreceived
+  // Stats below correspond to similarly-named fields in the WebRTC stats spec.
+  // https://w3c.github.io/webrtc-stats/#dom-rtcmediastreamtrackstats
   uint64_t total_samples_received = 0;
-  // Total number of inbound audio samples that are based on synthesized data to
-  // conceal packet loss.
-  // https://w3c.github.io/webrtc-stats/#dom-rtcmediastreamtrackstats-concealedsamples
   uint64_t concealed_samples = 0;
+  uint64_t concealment_events = 0;
 };
 
 enum NetEqPlayoutMode {

modules/audio_coding/neteq/neteq_impl.cc

@@ -847,7 +847,7 @@ int NetEqImpl::GetAudioInternal(AudioFrame* audio_frame, bool* muted) {
             : timestamp_scaler_->ToExternal(playout_timestamp_) -
                   static_cast<uint32_t>(audio_frame->samples_per_channel_);
     audio_frame->num_channels_ = sync_buffer_->Channels();
-    stats_.ExpandedNoiseSamples(output_size_samples_);
+    stats_.ExpandedNoiseSamples(output_size_samples_, false);
     *muted = true;
     return 0;
   }
@@ -1573,14 +1573,15 @@ int NetEqImpl::DoExpand(bool play_dtmf) {
     algorithm_buffer_->Clear();
     int return_value = expand_->Process(algorithm_buffer_.get());
     size_t length = algorithm_buffer_->Size();
+    bool is_new_concealment_event = (last_mode_ != kModeExpand);
 
     // Update in-call and post-call statistics.
     if (expand_->MuteFactor(0) == 0) {
       // Expand operation generates only noise.
-      stats_.ExpandedNoiseSamples(length);
+      stats_.ExpandedNoiseSamples(length, is_new_concealment_event);
     } else {
       // Expand operation generates more than only noise.
-      stats_.ExpandedVoiceSamples(length);
+      stats_.ExpandedVoiceSamples(length, is_new_concealment_event);
     }
 
     last_mode_ = kModeExpand;

modules/audio_coding/neteq/neteq_unittest.cc

@@ -1634,4 +1634,38 @@ TEST_F(NetEqDecodingTest, LastDecodedTimestampsTwoDecoded) {
             neteq_->LastDecodedTimestamps());
 }
 
+TEST_F(NetEqDecodingTest, TestConcealmentEvents) {
+  const int kNumConcealmentEvents = 19;
+  const size_t kSamples = 10 * 16;
+  const size_t kPayloadBytes = kSamples * 2;
+  int seq_no = 0;
+  RTPHeader rtp_info;
+  rtp_info.ssrc = 0x1234;     // Just an arbitrary SSRC.
+  rtp_info.payloadType = 94;  // PCM16b WB codec.
+  rtp_info.markerBit = 0;
+  const uint8_t payload[kPayloadBytes] = {0};
+  bool muted;
+
+  for (int i = 0; i < kNumConcealmentEvents; i++) {
+    // Insert some packets of 10 ms size.
+    for (int j = 0; j < 10; j++) {
+      rtp_info.sequenceNumber = seq_no++;
+      rtp_info.timestamp = rtp_info.sequenceNumber * kSamples;
+      neteq_->InsertPacket(rtp_info, payload, 0);
+      neteq_->GetAudio(&out_frame_, &muted);
+    }
+
+    // Lose a number of packets.
+    int num_lost = 1 + i;
+    for (int j = 0; j < num_lost; j++) {
+      seq_no++;
+      neteq_->GetAudio(&out_frame_, &muted);
+    }
+  }
+
+  // Check number of concealment events.
+  NetEqLifetimeStatistics stats = neteq_->GetLifetimeStatistics();
+  EXPECT_EQ(kNumConcealmentEvents, static_cast<int>(stats.concealment_events));
+}
+
 }  // namespace webrtc

modules/audio_coding/neteq/statistics_calculator.cc

@@ -151,14 +151,18 @@ void StatisticsCalculator::ResetMcu() {
   timestamps_since_last_report_ = 0;
 }
 
-void StatisticsCalculator::ExpandedVoiceSamples(size_t num_samples) {
+void StatisticsCalculator::ExpandedVoiceSamples(size_t num_samples,
+                                                bool is_new_concealment_event) {
   expanded_speech_samples_ += num_samples;
   lifetime_stats_.concealed_samples += num_samples;
+  lifetime_stats_.concealment_events += is_new_concealment_event;
 }
 
-void StatisticsCalculator::ExpandedNoiseSamples(size_t num_samples) {
+void StatisticsCalculator::ExpandedNoiseSamples(size_t num_samples,
+                                                bool is_new_concealment_event) {
   expanded_noise_samples_ += num_samples;
   lifetime_stats_.concealed_samples += num_samples;
+  lifetime_stats_.concealment_events += is_new_concealment_event;
 }
 
 void StatisticsCalculator::ExpandedVoiceSamplesCorrection(int num_samples) {

modules/audio_coding/neteq/statistics_calculator.h

@@ -39,11 +39,11 @@ class StatisticsCalculator {
 
   // Reports that |num_samples| samples were produced through expansion, and
   // that the expansion produced other than just noise samples.
-  void ExpandedVoiceSamples(size_t num_samples);
+  void ExpandedVoiceSamples(size_t num_samples, bool is_new_concealment_event);
 
   // Reports that |num_samples| samples were produced through expansion, and
   // that the expansion produced only noise samples.
-  void ExpandedNoiseSamples(size_t num_samples);
+  void ExpandedNoiseSamples(size_t num_samples, bool is_new_concealment_event);
 
   // Corrects the statistics for number of samples produced through non-noise
   // expansion by adding |num_samples| (negative or positive) to the current