changeset 684:49af9a8d5a53

Initial translation of SAI code to C++.

This only implements the simple (as opposed to the layered) SAI, as
implemented in SAI_Run.m.

--- a/trunk/carfac/SConstruct	Wed May 29 20:33:06 2013 +0000
+++ b/trunk/carfac/SConstruct	Fri May 31 21:46:48 2013 +0000
@@ -43,22 +43,6 @@
 import commands
 import os
 
-carfac_sources = [
-    'carfac_common.cc',
-    'agc_params.h',
-    'agc_coeffs.h',
-    'agc_state.h',
-    'carfac_output.cc',
-    'car_params.h',
-    'car_coeffs.h',
-    'ihc_params.h',
-    'car_state.h',
-    'ihc_coeffs.h',
-    'ihc_state.h',
-    'ear.cc',
-    'carfac.cc'
-    ]
-
 env = Environment(CPPPATH=[os.environ['EIGEN_PATH']])
 GCC_VERSION = commands.getoutput(env['CXX'] + ' -dumpversion')
 if GCC_VERSION.startswith('4.6'):
@@ -66,6 +50,22 @@
 else:
   env.MergeFlags(['-std=c++11'])
 
+carfac_sources = [
+    'agc_coeffs.h',
+    'agc_params.h',
+    'agc_state.h',
+    'car_coeffs.h',
+    'carfac.cc',
+    'carfac_common.cc',
+    'carfac_output.cc',
+    'car_params.h',
+    'car_state.h',
+    'ear.cc',
+    'ihc_coeffs.h',
+    'ihc_params.h',
+    'ihc_state.h',
+    'sai.cc',
+    ]
 env.Library(target = 'carfac', source = carfac_sources)
 
 env.Command('tmp/libgtest.a', [],
@@ -75,8 +75,12 @@
                 'cd tmp && cmake . && make',
             ])
 
-test_program = env.Program(target = 'carfac_test',
-                           source = ['carfac_test.cc'],
+test_sources = [
+    'carfac_test.cc',
+    'sai_test.cc',
+    ]
+test_program = env.Program(target = 'test',
+                           source = test_sources,
                            LIBS = ['carfac', 'gtest', 'gtest_main', 'pthread'],
                            LIBPATH = ['.', 'tmp'])
 test_alias = Alias('test', [test_program], test_program[0].abspath)

--- a/trunk/carfac/carfac_common.h	Wed May 29 20:33:06 2013 +0000
+++ b/trunk/carfac/carfac_common.h	Fri May 31 21:46:48 2013 +0000
@@ -60,6 +60,7 @@
 // A typedef is used to define a one-dimensional Eigen array with the same
 // precision level as FPType.
 typedef Eigen::Array<FPType, Dynamic, 1> FloatArray;
+typedef Eigen::Array<FPType, Dynamic, Dynamic> Float2dArray;
 
 // A fixed value of PI is defined throughout the project.
 static const FPType kPi = 3.141592653589793238;

--- a/trunk/carfac/carfac_test.cc	Wed May 29 20:33:06 2013 +0000
+++ b/trunk/carfac/carfac_test.cc	Fri May 31 21:46:48 2013 +0000
@@ -23,7 +23,8 @@
 #include <string>
 #include <fstream>
 #include <vector>
-#include <gtest/gtest.h>
+
+#include "gtest/gtest.h"
 #include "car_params.h"
 #include "ihc_params.h"
 #include "agc_params.h"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trunk/carfac/sai.cc	Fri May 31 21:46:48 2013 +0000
@@ -0,0 +1,100 @@
+// Copyright 2013, Google, Inc.
+// Author: Ron Weiss <[e-mail]>
+//
+// This C++ file is part of an implementation of Lyon's cochlear model:
+// "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+// to supplement Lyon's upcoming book "Human and Machine Hearing"
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <assert.h>
+
+#include "sai.h"
+
+SAI::SAI(const SAIParams& params) : params_(params) {
+  assert(params_.window_width > params_.width &&
+         "SAI window_width must be larger than width.");
+
+  int buffer_width = params_.width +
+      static_cast<int>((1 + static_cast<float>(params_.n_window_pos - 1)/2) *
+                       params_.window_width);
+  input_buffer_.setZero(params_.n_ch, buffer_width);
+  output_buffer_.setZero(params_.n_ch, params_.width);
+
+  window_.setLinSpaced(params_.window_width, kPi / params_.window_width, kPi)
+      .sin();
+}
+
+void SAI::RunSegment(const std::vector<FloatArray>& input,
+                     Float2dArray* output_frame) {
+  assert(!input.empty() || input.size() <= params_.window_width &&
+         "Unexpected input size.");
+  assert(input[0].size() == params_.n_ch &&
+         "Unexpected input frame size.");
+
+  // Append new data to the input buffer.
+  int n_shift = input.size();
+  int shift_width = input_buffer_.cols() - n_shift;
+  input_buffer_.topLeftCorner(params_.n_ch, shift_width).swap(
+      input_buffer_.block(0, n_shift, params_.n_ch, shift_width));
+  for (int i = 0; i < input.size(); ++i) {
+    input_buffer_.block(0, shift_width + i, input[i].size(), 1) = input[i];
+  }
+  // Zero-pad the buffer if necessary.
+  if (input.size() < params_.window_width) {
+    int pad_width = params_.window_width - input.size();
+    input_buffer_.topRightCorner(params_.n_ch, pad_width).setZero();
+  }
+
+  StabilizeSegment(input_buffer_, &output_buffer_);
+  *output_frame = output_buffer_;
+}
+
+void SAI::StabilizeSegment(const Float2dArray& input_buffer,
+                           Float2dArray* output_buffer) const {
+  // Windows are always approximately 50% overlapped.
+  float window_hop = params_.window_width / 2;
+  int window_start = (input_buffer.cols() - params_.window_width) -
+      (params_.n_window_pos - 1) * window_hop;
+  int window_range_start = window_start - params_.future_lags - 1;
+  int offset_range_start = window_start - params_.width;
+  assert(offset_range_start >= 0);
+  for (int i = 0; i < params_.n_ch; ++i) {
+    // TODO(ronw): Rename this here and in the Matlab code since the
+    // input doesn't have to contain naps.
+    const FloatArray& nap_wave = input_buffer.row(i);
+    // TODO(ronw): Smooth row.
+
+    for (int w = 0; w < params_.n_window_pos; ++w) {
+      int current_window_offset = w * window_hop;
+      // Choose a trigger point.
+      int trigger_time;
+      const FloatArray& trigger_window =
+          nap_wave.segment(window_range_start + current_window_offset,
+                           params_.window_width);
+      FPType peak_val = (trigger_window * window_).maxCoeff(&trigger_time);
+      if (peak_val <= 0) {
+        peak_val = window_.maxCoeff(&trigger_time);
+      }
+      trigger_time += current_window_offset;
+
+      // Blend the window following the trigger into the output
+      // buffer, weighted according to the the trigger strength (0.05
+      // to near 1.0).
+      FPType alpha = (0.025 + peak_val) / (0.5 + peak_val);
+      output_buffer->row(i) *= 1 - alpha;
+      output_buffer->row(i) += alpha *
+          nap_wave.segment(trigger_time + offset_range_start, params_.width);
+    }
+  }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trunk/carfac/sai.h	Fri May 31 21:46:48 2013 +0000
@@ -0,0 +1,81 @@
+// Copyright 2013, Google, Inc.
+// Author: Ron Weiss <[e-mail]>
+//
+// This C++ file is part of an implementation of Lyon's cochlear model:
+// "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+// to supplement Lyon's upcoming book "Human and Machine Hearing"
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CARFAC_SAI_H_
+#define CARFAC_SAI_H_
+
+#include <vector>
+
+// TODO(ronw): Rename this file to common.h
+#include "carfac_common.h"
+
+// Design parameters for a single SAI.
+struct SAIParams {
+  // Number of channels (height) of the SAI.
+  int n_ch;
+
+  // TODO(ronw): Consider parameterizing this as past_lags and
+  // future_lags, with width == past_lags + 1 + future_lags.
+  //
+  // Total width (i.e. number of lag samples) of the SAI.
+  int width;
+  // Number of lag samples that should come from the future.
+  int future_lags;
+  // Number of windows (triggers) to consider during each SAI frame.
+  int n_window_pos;
+
+  // TODO(ronw): more carefully define terms "window" and "frame"
+
+  // Size of the window to compute.
+  int window_width;
+
+  FPType channel_smoothing_scale;
+};
+
+class SAI {
+ public:
+  explicit SAI(const SAIParams& params);
+
+  // Fill output_frame with a params_.n_ch by params_.width SAI frame
+  // computed from the given input frames.
+  //
+  // The input should have dimensionality of params_.window_width by
+  // params_.n_ch.  Inputs containing too few frames are zero-padded.
+  // FIXME: Float2DArray input type would be less awkward.
+  void RunSegment(const std::vector<FloatArray>& input,
+                  Float2dArray* output_output_frame);
+
+ private:
+  // Process successive windows within input_buffer, choose trigger
+  // points, and blend each window into output_buffer.
+  void StabilizeSegment(const Float2dArray& input_buffer,
+                        Float2dArray* output_buffer) const;
+
+  SAIParams params_;
+  // Window function to apply before selecting a trigger point.
+  // Size: params_.window_width.
+  FloatArray window_;
+  // Buffer to store a large enough window of input frames to compute
+  // a full SAI frame.  Size: params_.n_ch by params_.buffer_width.
+  Float2dArray input_buffer_;
+  // Output frame buffer.  Size: params_.n_ch by params_.width.
+  Float2dArray output_buffer_;
+};
+
+#endif  // CARFAC_SAI_H_

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trunk/carfac/sai_test.cc	Fri May 31 21:46:48 2013 +0000
@@ -0,0 +1,95 @@
+// Copyright 2013, Google, Inc.
+// Author: Ron Weiss <[e-mail]>
+//
+// This C++ file is part of an implementation of Lyon's cochlear model:
+// "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+// to supplement Lyon's upcoming book "Human and Machine Hearing"
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "sai.h"
+
+#include <iostream>
+#include <vector>
+
+#include "gtest/gtest.h"
+
+using testing::Values;
+using std::vector;
+
+vector<FloatArray> CreateZeroSegment(int n_ch, int length) {
+  vector<FloatArray> segment;
+  for (int i = 0; i < length; ++i) {
+    segment.push_back(FloatArray::Zero(n_ch));
+  }
+  return segment;
+}
+
+bool HasPeakAt(const Float2dArray& frame, int index) {
+  if (index == 0) {
+    return frame(index) > frame(index + 1);
+  } else if (index == frame.size() - 1) {
+    return frame(index) > frame(index - 1);
+  }
+  return frame(index) > frame(index + 1) && frame(index) > frame(index - 1);
+}
+
+class SAIPeriodicInputTest
+    : public testing::TestWithParam<std::tr1::tuple<int, int>> {
+ protected:
+  void SetUp() {
+    period_ = std::tr1::get<0>(GetParam());
+    phase_ = std::tr1::get<1>(GetParam());
+  }
+
+  int period_;
+  int phase_;
+};
+
+TEST_P(SAIPeriodicInputTest, SingleChannelPulseTrain) {
+  vector<FloatArray> segment = CreateZeroSegment(1, 38);
+  for (int i = phase_; i < segment.size(); i += period_) {
+    segment[i](0) = 1;
+  }
+
+  SAIParams sai_params;
+  sai_params.window_width = segment.size();
+  sai_params.n_ch = 1;
+  sai_params.width = 15;
+  // Half of the SAI should come from the future.
+  // sai_params.future_lags = sai_params.width / 2;
+  sai_params.future_lags = 0;
+  sai_params.n_window_pos = 2;
+
+  SAI sai(sai_params);
+  Float2dArray sai_frame;
+  sai.RunSegment(segment, &sai_frame);
+
+  // The output should have peaks at the same positions, regardless of
+  // input phase.
+  for (int i = sai_frame.size() - 1; i >= 0 ; i -= period_) {
+    EXPECT_TRUE(HasPeakAt(sai_frame, i));
+  }
+
+  for (int i = 0; i < segment.size(); ++i) {
+    std::cout << segment[i](0) << " ";
+  }
+  std::cout << "\n";
+  for (int i = 0; i < sai_frame.size(); ++i) {
+    std::cout << sai_frame(i) << " ";
+  }
+  std::cout << "\n";
+}
+INSTANTIATE_TEST_CASE_P(PeriodicInputVariations, SAIPeriodicInputTest,
+                        testing::Combine(Values(25, 10, 5, 2),  // periods.
+                                         Values(0, 3)));  // phases.