Revert of VCMCodecTimer: Change filter from max to 95th percentile

webrtc/modules/video_coding/codec_timer.cc

Index: webrtc/modules/video_coding/codec_timer.cc
diff --git a/webrtc/modules/video_coding/codec_timer.cc b/webrtc/modules/video_coding/codec_timer.cc
index 0fdf1a692e438137c23fa69f3611936d7bb10848..60add8fc4bae3fbf30475d9c00d5a7d0826373d6 100644
--- a/webrtc/modules/video_coding/codec_timer.cc
+++ b/webrtc/modules/video_coding/codec_timer.cc
@@ -10,47 +10,87 @@
 
 #include "webrtc/modules/video_coding/codec_timer.h"
 
+#include <assert.h>
+
 namespace webrtc {
 
-namespace {
-
 // The first kIgnoredSampleCount samples will be ignored.
-const int kIgnoredSampleCount = 5;
-// Return the |kPercentile| value in RequiredDecodeTimeMs().
-const float kPercentile = 0.95f;
-// The window size in ms.
-const int64_t kTimeLimitMs = 10000;
-
-}  // anonymous namespace
+static const int32_t kIgnoredSampleCount = 5;
 
 VCMCodecTimer::VCMCodecTimer()
-    : ignored_sample_count_(0), filter_(kPercentile) {}
+    : _filteredMax(0), _ignoredSampleCount(0), _shortMax(0), _history() {
+  Reset();
+}
 
-void VCMCodecTimer::AddTiming(int64_t decode_time_ms, int64_t now_ms) {
-  // Ignore the first |kIgnoredSampleCount| samples.
-  if (ignored_sample_count_ < kIgnoredSampleCount) {
-    ++ignored_sample_count_;
-    return;
-  }
-
-  // Insert new decode time value.
-  filter_.Insert(decode_time_ms);
-  history_.emplace(decode_time_ms, now_ms);
-
-  // Pop old decode time values.
-  while (!history_.empty() &&
-         now_ms - history_.front().sample_time_ms > kTimeLimitMs) {
-    filter_.Erase(history_.front().decode_time_ms);
-    history_.pop();
+void VCMCodecTimer::Reset() {
+  _filteredMax = 0;
+  _ignoredSampleCount = 0;
+  _shortMax = 0;
+  for (int i = 0; i < MAX_HISTORY_SIZE; i++) {
+    _history[i].shortMax = 0;
+    _history[i].timeMs = -1;
   }
 }
 
-// Get the 95th percentile observed decode time within a time window.
-int64_t VCMCodecTimer::RequiredDecodeTimeMs() const {
-  return filter_.GetPercentileValue();
+// Update the max-value filter
+void VCMCodecTimer::MaxFilter(int32_t decodeTime, int64_t nowMs) {
+  if (_ignoredSampleCount >= kIgnoredSampleCount) {
+    UpdateMaxHistory(decodeTime, nowMs);
+    ProcessHistory(nowMs);
+  } else {
+    _ignoredSampleCount++;
+  }
 }
 
-VCMCodecTimer::Sample::Sample(int64_t decode_time_ms, int64_t sample_time_ms)
-    : decode_time_ms(decode_time_ms), sample_time_ms(sample_time_ms) {}
+void VCMCodecTimer::UpdateMaxHistory(int32_t decodeTime, int64_t now) {
+  if (_history[0].timeMs >= 0 && now - _history[0].timeMs < SHORT_FILTER_MS) {
+    if (decodeTime > _shortMax) {
+      _shortMax = decodeTime;
+    }
+  } else {
+    // Only add a new value to the history once a second
+    if (_history[0].timeMs == -1) {
+      // First, no shift
+      _shortMax = decodeTime;
+    } else {
+      // Shift
+      for (int i = (MAX_HISTORY_SIZE - 2); i >= 0; i--) {
+        _history[i + 1].shortMax = _history[i].shortMax;
+        _history[i + 1].timeMs = _history[i].timeMs;
+      }
+    }
+    if (_shortMax == 0) {
+      _shortMax = decodeTime;
+    }
 
+    _history[0].shortMax = _shortMax;
+    _history[0].timeMs = now;
+    _shortMax = 0;
+  }
+}
+
+void VCMCodecTimer::ProcessHistory(int64_t nowMs) {
+  _filteredMax = _shortMax;
+  if (_history[0].timeMs == -1) {
+    return;
+  }
+  for (int i = 0; i < MAX_HISTORY_SIZE; i++) {
+    if (_history[i].timeMs == -1) {
+      break;
+    }
+    if (nowMs - _history[i].timeMs > MAX_HISTORY_SIZE * SHORT_FILTER_MS) {
+      // This sample (and all samples after this) is too old
+      break;
+    }
+    if (_history[i].shortMax > _filteredMax) {
+      // This sample is the largest one this far into the history
+      _filteredMax = _history[i].shortMax;
+    }
+  }
+}
+
+// Get the maximum observed time within a time window
+int32_t VCMCodecTimer::RequiredDecodeTimeMs(FrameType /*frameType*/) const {
+  return _filteredMax;
+}
 }  // namespace webrtc