Raw packet loss rate reported by RTP_RTCP module may vary too drastically over time. This CL is to add a filter to the value in VoE before lending it to audio coding module.

The filter is an exponential filter borrowed from video coding module.

The method is written in a new class called PacketLossProtector (not sure if the name is nice), which can be used in the future for more sophisticated logic.

BUG=
R=henrika@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/20809004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@6709 4adac7df-926f-26a2-2b94-8c16560cd09d

7 files changed, 61 insertions, 177 deletions

diff --git a/modules/video_coding/main/source/media_opt_util.cc b/modules/video_coding/main/source/media_opt_util.cc
index ba86575f..b506a5b5 100644
--- a/modules/video_coding/main/source/media_opt_util.cc
+++ b/modules/video_coding/main/source/media_opt_util.cc
@@ -837,7 +837,7 @@ uint8_t VCMLossProtectionLogic::FilteredLoss(
     case kNoFilter:
       break;
     case kAvgFilter:
-      filtered_loss = static_cast<uint8_t> (_lossPr255.Value() + 0.5);
+      filtered_loss = static_cast<uint8_t>(_lossPr255.filtered() + 0.5);
       break;
     case kMaxFilter:
       filtered_loss = MaxFilteredLossPr(nowMs);
@@ -907,8 +907,8 @@ VCMLossProtectionLogic::UpdateMethod()
     _currentParameters.keyFrameSize = _keyFrameSize;
     _currentParameters.fecRateDelta = _fecRateDelta;
     _currentParameters.fecRateKey = _fecRateKey;
-    _currentParameters.packetsPerFrame = _packetsPerFrame.Value();
-    _currentParameters.packetsPerFrameKey = _packetsPerFrameKey.Value();
+    _currentParameters.packetsPerFrame = _packetsPerFrame.filtered();
+    _currentParameters.packetsPerFrameKey = _packetsPerFrameKey.filtered();
     _currentParameters.residualPacketLossFec = _residualPacketLossFec;
     _currentParameters.codecWidth = _codecWidth;
     _currentParameters.codecHeight = _codecHeight;
diff --git a/modules/video_coding/main/source/media_opt_util.h b/modules/video_coding/main/source/media_opt_util.h
index f39a5780..d421d9e7 100644
--- a/modules/video_coding/main/source/media_opt_util.h
+++ b/modules/video_coding/main/source/media_opt_util.h
@@ -14,9 +14,9 @@
 #include <math.h>
 #include <stdlib.h>
 
+#include "webrtc/base/exp_filter.h"
 #include "webrtc/modules/video_coding/main/source/internal_defines.h"
 #include "webrtc/modules/video_coding/main/source/qm_select.h"
-#include "webrtc/modules/video_coding/utility/include/exp_filter.h"
 #include "webrtc/system_wrappers/interface/trace.h"
 #include "webrtc/typedefs.h"
 
@@ -367,27 +367,27 @@ private:
     // Sets the available loss protection methods.
     void UpdateMaxLossHistory(uint8_t lossPr255, int64_t now);
     uint8_t MaxFilteredLossPr(int64_t nowMs) const;
-    VCMProtectionMethod*      _selectedMethod;
-    VCMProtectionParameters   _currentParameters;
-    uint32_t            _rtt;
-    float                     _lossPr;
-    float                     _bitRate;
-    float                     _frameRate;
-    float                     _keyFrameSize;
-    uint8_t             _fecRateKey;
-    uint8_t             _fecRateDelta;
-    int64_t             _lastPrUpdateT;
-    int64_t             _lastPacketPerFrameUpdateT;
-    int64_t             _lastPacketPerFrameUpdateTKey;
-    VCMExpFilter              _lossPr255;
-    VCMLossProbabilitySample  _lossPrHistory[kLossPrHistorySize];
-    uint8_t             _shortMaxLossPr255;
-    VCMExpFilter              _packetsPerFrame;
-    VCMExpFilter              _packetsPerFrameKey;
-    float                     _residualPacketLossFec;
-    uint16_t            _codecWidth;
-    uint16_t            _codecHeight;
-    int                       _numLayers;
+    VCMProtectionMethod* _selectedMethod;
+    VCMProtectionParameters _currentParameters;
+    uint32_t _rtt;
+    float _lossPr;
+    float _bitRate;
+    float _frameRate;
+    float _keyFrameSize;
+    uint8_t _fecRateKey;
+    uint8_t _fecRateDelta;
+    int64_t _lastPrUpdateT;
+    int64_t _lastPacketPerFrameUpdateT;
+    int64_t _lastPacketPerFrameUpdateTKey;
+    rtc::ExpFilter _lossPr255;
+    VCMLossProbabilitySample _lossPrHistory[kLossPrHistorySize];
+    uint8_t _shortMaxLossPr255;
+    rtc::ExpFilter _packetsPerFrame;
+    rtc::ExpFilter _packetsPerFrameKey;
+    float _residualPacketLossFec;
+    uint16_t _codecWidth;
+    uint16_t _codecHeight;
+    int _numLayers;
 };
 
 }  // namespace media_optimization
diff --git a/modules/video_coding/utility/exp_filter.cc b/modules/video_coding/utility/exp_filter.cc
deleted file mode 100644
index 44f280bc..00000000
--- a/modules/video_coding/utility/exp_filter.cc
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/modules/video_coding/utility/include/exp_filter.h"
-
-#include <math.h>
-
-namespace webrtc {
-
-void
-VCMExpFilter::Reset(float alpha)
-{
-    _alpha = alpha;
-    _filtered = -1.0;
-}
-
-float
-VCMExpFilter::Apply(float exp, float sample)
-{
-    if (_filtered == -1.0)
-    {
-        // Initialize filtered bit rates
-        _filtered = sample;
-    }
-    else if (exp == 1.0)
-    {
-        _filtered = _alpha * _filtered + (1 - _alpha) * sample;
-    }
-    else
-    {
-        float alpha = pow(_alpha, exp);
-        _filtered = alpha * _filtered + (1 - alpha) * sample;
-    }
-    if (_max != -1 && _filtered > _max)
-    {
-        _filtered = _max;
-    }
-    return _filtered;
-}
-
-void
-VCMExpFilter::UpdateBase(float alpha)
-{
-    _alpha = alpha;
-}
-
-float
-VCMExpFilter::Value() const
-{
-    return _filtered;
-}
-
-}
diff --git a/modules/video_coding/utility/frame_dropper.cc b/modules/video_coding/utility/frame_dropper.cc
index d3c25fb9..54c8cb8a 100644
--- a/modules/video_coding/utility/frame_dropper.cc
+++ b/modules/video_coding/utility/frame_dropper.cc
@@ -86,25 +86,27 @@ FrameDropper::Fill(uint32_t frameSizeBytes, bool deltaFrame)
     {
         _keyFrameSizeAvgKbits.Apply(1, frameSizeKbits);
         _keyFrameRatio.Apply(1.0, 1.0);
-        if (frameSizeKbits > _keyFrameSizeAvgKbits.Value())
+        if (frameSizeKbits > _keyFrameSizeAvgKbits.filtered())
         {
             // Remove the average key frame size since we
             // compensate for key frames when adding delta
             // frames.
-            frameSizeKbits -= _keyFrameSizeAvgKbits.Value();
+            frameSizeKbits -= _keyFrameSizeAvgKbits.filtered();
         }
         else
         {
             // Shouldn't be negative, so zero is the lower bound.
             frameSizeKbits = 0;
         }
-        if (_keyFrameRatio.Value() > 1e-5 && 1 / _keyFrameRatio.Value() < _keyFrameSpreadFrames)
+        if (_keyFrameRatio.filtered() > 1e-5 &&
+            1 / _keyFrameRatio.filtered() < _keyFrameSpreadFrames)
         {
             // We are sending key frames more often than our upper bound for
             // how much we allow the key frame compensation to be spread
             // out in time. Therefor we must use the key frame ratio rather
             // than keyFrameSpreadFrames.
-            _keyFrameCount = static_cast<int32_t>(1 / _keyFrameRatio.Value() + 0.5);
+            _keyFrameCount =
+                static_cast<int32_t>(1 / _keyFrameRatio.filtered() + 0.5);
         }
         else
         {
@@ -145,13 +147,14 @@ FrameDropper::Leak(uint32_t inputFrameRate)
     if (_keyFrameCount > 0)
     {
         // Perform the key frame compensation
-        if (_keyFrameRatio.Value() > 0 && 1 / _keyFrameRatio.Value() < _keyFrameSpreadFrames)
+        if (_keyFrameRatio.filtered() > 0 &&
+            1 / _keyFrameRatio.filtered() < _keyFrameSpreadFrames)
         {
-            T -= _keyFrameSizeAvgKbits.Value() * _keyFrameRatio.Value();
+            T -= _keyFrameSizeAvgKbits.filtered() * _keyFrameRatio.filtered();
         }
         else
         {
-            T -= _keyFrameSizeAvgKbits.Value() / _keyFrameSpreadFrames;
+            T -= _keyFrameSizeAvgKbits.filtered() / _keyFrameSpreadFrames;
         }
         _keyFrameCount--;
     }
@@ -232,11 +235,11 @@ FrameDropper::DropFrame()
         _dropCount = 0;
     }
 
-    if (_dropRatio.Value() >= 0.5f) // Drops per keep
+    if (_dropRatio.filtered() >= 0.5f) // Drops per keep
     {
         // limit is the number of frames we should drop between each kept frame
         // to keep our drop ratio. limit is positive in this case.
-        float denom = 1.0f - _dropRatio.Value();
+        float denom = 1.0f - _dropRatio.filtered();
         if (denom < 1e-5)
         {
             denom = (float)1e-5;
@@ -252,7 +255,7 @@ FrameDropper::DropFrame()
         if (_dropCount < 0)
         {
             // Reset the _dropCount since it was negative and should be positive.
-            if (_dropRatio.Value() > 0.4f)
+            if (_dropRatio.filtered() > 0.4f)
             {
                 _dropCount = -_dropCount;
             }
@@ -274,12 +277,13 @@ FrameDropper::DropFrame()
             return false;
         }
     }
-    else if (_dropRatio.Value() > 0.0f && _dropRatio.Value() < 0.5f) // Keeps per drop
+    else if (_dropRatio.filtered() > 0.0f &&
+        _dropRatio.filtered() < 0.5f) // Keeps per drop
     {
         // limit is the number of frames we should keep between each drop
         // in order to keep the drop ratio. limit is negative in this case,
         // and the _dropCount is also negative.
-        float denom = _dropRatio.Value();
+        float denom = _dropRatio.filtered();
         if (denom < 1e-5)
         {
             denom = (float)1e-5;
@@ -289,7 +293,7 @@ FrameDropper::DropFrame()
         {
             // Reset the _dropCount since we have a positive
             // _dropCount, and it should be negative.
-            if (_dropRatio.Value() < 0.6f)
+            if (_dropRatio.filtered() < 0.6f)
             {
                 _dropCount = -_dropCount;
             }
@@ -350,7 +354,7 @@ FrameDropper::ActualFrameRate(uint32_t inputFrameRate) const
     {
         return static_cast<float>(inputFrameRate);
     }
-    return inputFrameRate * (1.0f - _dropRatio.Value());
+    return inputFrameRate * (1.0f - _dropRatio.filtered());
 }
 
 // Put a cap on the accumulator, i.e., don't let it grow beyond some level.
diff --git a/modules/video_coding/utility/include/exp_filter.h b/modules/video_coding/utility/include/exp_filter.h
deleted file mode 100644
index d8c37a30..00000000
--- a/modules/video_coding/utility/include/exp_filter.h
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_EXP_FILTER_H_
-#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_EXP_FILTER_H_
-
-namespace webrtc
-{
-
-/**********************/
-/* ExpFilter class    */
-/**********************/
-
-class VCMExpFilter
-{
-public:
-    VCMExpFilter(float alpha, float max = -1.0) : _alpha(alpha), _filtered(-1.0), _max(max) {}
-
-    // Resets the filter to its initial state, and resets alpha to the given value
-    //
-    // Input:
-    //          - alpha     : the new value of the filter factor base.
-    void Reset(float alpha);
-
-    // Applies the filter with the given exponent on the provided sample
-    //
-    // Input:
-    //          - exp       : Exponent T in y(k) = alpha^T * y(k-1) + (1 - alpha^T) * x(k)
-    //          - sample    : x(k) in the above filter equation
-    float Apply(float exp, float sample);
-
-    // Return current filtered value: y(k)
-    //
-    // Return value         : The current filter output
-    float Value() const;
-
-    // Change the filter factor base
-    //
-    // Input:
-    //          - alpha     : The new filter factor base.
-    void UpdateBase(float alpha);
-
-private:
-    float          _alpha;     // Filter factor base
-    float          _filtered;  // Current filter output
-    const float    _max;
-}; // end of ExpFilter class
-
-}  // namespace webrtc
-
-#endif // WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_EXP_FILTER_H_
diff --git a/modules/video_coding/utility/include/frame_dropper.h b/modules/video_coding/utility/include/frame_dropper.h
index 4c1c168c..8eebd784 100644
--- a/modules/video_coding/utility/include/frame_dropper.h
+++ b/modules/video_coding/utility/include/frame_dropper.h
@@ -11,7 +11,7 @@
 #ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_FRAME_DROPPER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_FRAME_DROPPER_H_
 
-#include "webrtc/modules/video_coding/utility/include/exp_filter.h"
+#include "webrtc/base/exp_filter.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc
@@ -72,23 +72,23 @@ private:
     void UpdateRatio();
     void CapAccumulator();
 
-    VCMExpFilter       _keyFrameSizeAvgKbits;
-    VCMExpFilter       _keyFrameRatio;
-    float           _keyFrameSpreadFrames;
-    int32_t     _keyFrameCount;
-    float           _accumulator;
-    float           _accumulatorMax;
-    float           _targetBitRate;
-    bool            _dropNext;
-    VCMExpFilter       _dropRatio;
-    int32_t     _dropCount;
-    float           _windowSize;
-    float           _incoming_frame_rate;
-    bool            _wasBelowMax;
-    bool            _enabled;
-    bool            _fastMode;
-    float           _cap_buffer_size;
-    float           _max_time_drops;
+    rtc::ExpFilter _keyFrameSizeAvgKbits;
+    rtc::ExpFilter _keyFrameRatio;
+    float _keyFrameSpreadFrames;
+    int32_t _keyFrameCount;
+    float _accumulator;
+    float _accumulatorMax;
+    float _targetBitRate;
+    bool _dropNext;
+    rtc::ExpFilter _dropRatio;
+    int32_t _dropCount;
+    float _windowSize;
+    float _incoming_frame_rate;
+    bool _wasBelowMax;
+    bool _enabled;
+    bool _fastMode;
+    float _cap_buffer_size;
+    float _max_time_drops;
 }; // end of VCMFrameDropper class
 
 }  // namespace webrtc
diff --git a/modules/video_coding/utility/video_coding_utility.gyp b/modules/video_coding/utility/video_coding_utility.gyp
index 24f88800..2f0202b1 100644
--- a/modules/video_coding/utility/video_coding_utility.gyp
+++ b/modules/video_coding/utility/video_coding_utility.gyp
@@ -18,9 +18,7 @@
         '<(webrtc_root)/system_wrappers/source/system_wrappers.gyp:system_wrappers',
       ],
       'sources': [
-        'include/exp_filter.h',
         'include/frame_dropper.h',
-        'exp_filter.cc',
         'frame_dropper.cc',
       ],
     },