Report max interframe delay over window insdead of interframe delay sum

webrtc/video/receive_statistics_proxy.cc

Index: webrtc/video/receive_statistics_proxy.cc
diff --git a/webrtc/video/receive_statistics_proxy.cc b/webrtc/video/receive_statistics_proxy.cc
index 7852a059134c47e17a198612385afd0ed35d2fa2..e51315bed5526c297a2ffeddd4e8c8e8b82aa478 100644
--- a/webrtc/video/receive_statistics_proxy.cc
+++ b/webrtc/video/receive_statistics_proxy.cc
@@ -43,6 +43,9 @@ const int kHighQpThresholdVp8 = 70;
 const int kLowVarianceThreshold = 1;
 const int kHighVarianceThreshold = 2;
 
+// Some metrics are reported as a maximum over this period.
+const int kMovingMaxWindowMs = 5000;

[sprang_webrtc, 2017/08/18 09:06:49]

I think this interval needs to be longer. At least 10s.
Also, document it in the api.

[ilnik, 2017/08/18 11:43:01]

Done.

+
 // How large window we use to calculate the framerate/bitrate.
 const int kRateStatisticsWindowSizeMs = 1000;
 }  // namespace
@@ -78,6 +81,7 @@ ReceiveStatisticsProxy::ReceiveStatisticsProxy(
       e2e_delay_max_ms_screenshare_(-1),
       interframe_delay_max_ms_video_(-1),
       interframe_delay_max_ms_screenshare_(-1),
+      interframe_delay_max_moving_(kMovingMaxWindowMs),
       freq_offset_counter_(clock, nullptr, kFreqOffsetProcessIntervalMs),
       first_report_block_time_ms_(-1),
       avg_rtt_ms_(0),
@@ -394,6 +398,8 @@ VideoReceiveStream::Stats ReceiveStatisticsProxy::GetStats() const {
   stats_.decode_frame_rate = decode_fps_estimator_.Rate(now_ms).value_or(0);
   stats_.total_bitrate_bps =
       static_cast<int>(total_byte_tracker_.ComputeRate() * 8);
+  stats_.interframe_delay_max_ms =
+      interframe_delay_max_moving_.MovingMax(now_ms).value_or(0);
   return stats_;
 }
 
@@ -544,7 +550,7 @@ void ReceiveStatisticsProxy::OnDecodedFrame(rtc::Optional<uint8_t> qp,
   if (last_decoded_frame_time_ms_) {
     int64_t interframe_delay_ms = now - *last_decoded_frame_time_ms_;
     RTC_DCHECK_GE(interframe_delay_ms, 0);
-    stats_.interframe_delay_sum_ms += interframe_delay_ms;
+    interframe_delay_max_moving_.Add(interframe_delay_ms, now);
     if (last_content_type_ == VideoContentType::SCREENSHARE) {
       interframe_delay_counter_screenshare_.Add(interframe_delay_ms);
       if (interframe_delay_max_ms_screenshare_ < interframe_delay_ms) {
@@ -665,6 +671,45 @@ void ReceiveStatisticsProxy::SampleCounter::Reset() {
   sum = 0;
 }
 
+void ReceiveStatisticsProxy::MovingMaxCounter::Add(int sample,
+                                                   int64_t time_ms) {
+  int64_t window_begin_ms = time_ms - window_length_ms_;
+  // Throw out obsolete samples.
+  while (!samples_.empty() && samples_.front().first < window_begin_ms) {
+    samples_.pop_front();
+  }
+  // Remove samples what will never be maximum in any window: newly added sample
+  // will always be in all windows the previous samples are. Thus, smaller
+  // samples could be removed. This will maintain the invariant - deque contains
+  // non-increasing sequence of values.
+  while (!samples_.empty() && samples_.back().second < sample) {
+    samples_.pop_back();
+  }
+  samples_.push_back(std::make_pair(time_ms, sample));

[sprang_webrtc, 2017/08/18 09:06:49]

emplace_back even?

[ilnik, 2017/08/18 11:43:01]

Done.

+}
+
+rtc::Optional<int> ReceiveStatisticsProxy::MovingMaxCounter::MovingMax(
+    int64_t time_ms) const {
+  rtc::Optional<int> res;
+  if (samples_.empty()) {
+      return res;
+  }
+  int64_t window_begin_ms = time_ms - window_length_ms_;
+  auto it = samples_.begin();
+  while (it != samples_.end() && it->first < window_begin_ms) {
+    ++it;
+  }
+  if (it != samples_.end()) {
+    res.emplace(it->second);
+  }
+  return res;
+}
+
+void ReceiveStatisticsProxy::MovingMaxCounter::Reset() {
+  samples_.clear();
+}
+
+
 void ReceiveStatisticsProxy::OnRttUpdate(int64_t avg_rtt_ms,
                                          int64_t max_rtt_ms) {
   rtc::CritScope lock(&crit_);