NetEq: Implement Average Excess Buffer Delay stats

webrtc/modules/audio_coding/neteq/statistics_calculator.h

Index: webrtc/modules/audio_coding/neteq/statistics_calculator.h
diff --git a/webrtc/modules/audio_coding/neteq/statistics_calculator.h b/webrtc/modules/audio_coding/neteq/statistics_calculator.h
index c27aabe1281b757926df125dbc4abf85c86907ee..bd14530f0e3aa813a59f2e6c9a55cf8bcb83e38b 100644
--- a/webrtc/modules/audio_coding/neteq/statistics_calculator.h
+++ b/webrtc/modules/audio_coding/neteq/statistics_calculator.h
@@ -113,6 +113,24 @@ class StatisticsCalculator {
     int timer_ = 0;
   };
 
+  class AverageExcessBufferDelayMs {

[minyue-webrtc, 2015/08/17 13:38:08]

Since AverageExcessBufferDelayMs and DelayedPacketOutagesPerMinuteCounter and
probably others are similar in implementation, is it possible to create a common
ancestor to share codes, and use a list of the parent class to hold them to
avoid explicitly calling the AdvanceClock() one-by-one, or optionally use a
manager to hold them and put the operations inside the manager?

[hlundin-webrtc, 2015/08/18 07:41:44]

I thought about it at first. And now I tried it, but it gets messy for a number
of reasons. See draft CL: https://codereview.webrtc.org/1289753008/-
- The two use different logging macros; RTC_HISTOGRAM_COUNTS_100 vs
RTC_HISTOGRAM_COUNTS_1000. They both expand to the same underlying macro, so I
could generalize to that, but that means adding another state variable that
keeps track of the range (100 vs 1000).
- They require different input. One just registers that events happen (void
input) while the other registers magnitudes of events (int input).
Specialization needed.
- And since they would require different input parameters for the event
registration, the owner must know the actual class type, and not just the
(presumed) base logger class type. So, we would not really have a list of
objects that can be traversed.

I could add a manager class, but I see little value when the only thing it would
do is batch-call the AdvanceClock method.

+   public:
+    ~AverageExcessBufferDelayMs() {
+      LogToUma();  // Log the average for the current (incomplete) interval.
+    }
+    void RegisterPacketWaitingTime(int time_ms);
+    void AdvanceClock(int step_ms);
+
+   private:
+    static const int kReportIntervalMs = 60 * 1000;  // One minute.
+
+    void LogToUma();
+
+    double sum_ = 0.0;
+    int num_packets_ = 0;
+    int timer_ = 0;
+  };
+
   // Calculates numerator / denominator, and returns the value in Q14.
   static uint16_t CalculateQ14Ratio(uint32_t numerator, uint32_t denominator);
 
@@ -129,6 +147,7 @@ class StatisticsCalculator {
   int next_waiting_time_index_;
   uint32_t secondary_decoded_samples_;
   DelayedPacketOutagesPerMinuteCounter delayed_packet_outage_counter_;
+  AverageExcessBufferDelayMs excess_buffer_delay_;
 
   DISALLOW_COPY_AND_ASSIGN(StatisticsCalculator);
 };