view trunk/carfac/sai.cc @ 690:76f749d29b48

Fix memory leak in CARFAC.

Also get rid of most uses of auto, which tend to hurt readability
unless the type name is particularly long, especially when it masks
pointers.

// 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 <assert.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<ArrayX>& input,
                     ArrayXX* 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 ArrayXX& input_buffer,
                           ArrayXX* 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 ArrayX& 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 ArrayX& 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);
    }
  }
}