VCMCodecTimer: Change filter from max to 95th percentile

webrtc/modules/video_coding/codec_timer.h

Index: webrtc/modules/video_coding/codec_timer.h
diff --git a/webrtc/modules/video_coding/codec_timer.h b/webrtc/modules/video_coding/codec_timer.h
index 8ebd82ab9c240f38070f6ef23ec5fa0ae81ccec4..8f400fd8bffd66978cba85323a08e585e77c4522 100644
--- a/webrtc/modules/video_coding/codec_timer.h
+++ b/webrtc/modules/video_coding/codec_timer.h
@@ -11,45 +11,42 @@
 #ifndef WEBRTC_MODULES_VIDEO_CODING_CODEC_TIMER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_CODEC_TIMER_H_
 
+#include <queue>
+
 #include "webrtc/modules/include/module_common_types.h"
+#include "webrtc/modules/video_coding/percentile_filter.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
-// MAX_HISTORY_SIZE * SHORT_FILTER_MS defines the window size in milliseconds
-#define MAX_HISTORY_SIZE 10
-#define SHORT_FILTER_MS 1000
-
-class VCMShortMaxSample {
- public:
-  VCMShortMaxSample() : shortMax(0), timeMs(-1) {}
-
-  int32_t shortMax;
-  int64_t timeMs;
-};
-
 class VCMCodecTimer {
  public:
   VCMCodecTimer();
 
-  // Updates the max filtered decode time.
-  void MaxFilter(int32_t newDecodeTimeMs, int64_t nowMs);
+  // Add a new decode time to the filter.
+  void AddTiming(int64_t new_decode_time_ms, int64_t now_ms);
 
-  // Empty the list of timers.
+  // Restore to the ctor state.
   void Reset();

[stefan-webrtc, 2016/03/07 14:48:59]

Maybe we should remove this method and instead recreate the object. WDYT?

[magjed_webrtc, 2016/03/08 15:49:42]

I agree. Done.

 
-  // Get the required decode time in ms.
-  int32_t RequiredDecodeTimeMs(FrameType frameType) const;
+  // Get the required decode time in ms. It is the 95th percentile observed
+  // decode time within a time window.
+  int64_t RequiredDecodeTimeMs() const;
 
  private:
-  void UpdateMaxHistory(int32_t decodeTime, int64_t now);
-  void ProcessHistory(int64_t nowMs);
+  struct Sample {
+    Sample(int64_t decode_time_ms, int64_t sample_time_ms);
+    int64_t decode_time_ms;
+    int64_t sample_time_ms;
+  };
 
-  int32_t _filteredMax;
   // The number of samples ignored so far.
-  int32_t _ignoredSampleCount;
-  int32_t _shortMax;
-  VCMShortMaxSample _history[MAX_HISTORY_SIZE];
+  int ignoredSampleCount_;

[stefan-webrtc, 2016/03/07 14:48:59]

ignored_sample_count_

[magjed_webrtc, 2016/03/08 15:49:42]

Done.

+  // Queue with history of latest decode time values.
+  std::queue<Sample> history_;
+  // |filter_| contains the same values as |history_|, but in a data structure
+  // that allows efficient retrieval of the percentile value.
+  PercentileFilter filter_;
 };
 
 }  // namespace webrtc