diff src/Modules/NAP/ModuleHCL.cc @ 0:582cbe817f2c

- Initial add of support code and modules. Not everything is working yet.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Modules/NAP/ModuleHCL.cc	Fri Feb 12 12:31:23 2010 +0000
@@ -0,0 +1,110 @@
+// Copyright 2007-2010, Thomas Walters
+//
+// AIM-C: A C++ implementation of the Auditory Image Model
+// http://www.acousticscale.org/AIMC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+/*!
+ * \file
+ * \brief Halfwave rectification, compression and lowpass filtering.
+ *
+ * \author Tom Walters <[e-mail]>
+ * \date created 2007/03/07
+ * \version \$Id: ModuleHCL.cc 4 2010-02-03 18:44:58Z tcw $
+ */
+
+#include <math.h>
+
+#include "Modules/NAP/ModuleHCL.h"
+
+namespace aimc {
+ModuleHCL::ModuleHCL(Parameters *parameters) : Module(parameters) {
+  module_identifier_ = "hcl";
+  module_type_ = "nap";
+  module_description_ = "Halfwave rectification, compression "
+                        "and lowpass filtering";
+  module_version_ = "$Id: ModuleHCL.cc 4 2010-02-03 18:44:58Z tcw $";
+
+  parameters_->SetDefault("nap.do_lowpass", "false");
+  parameters_->SetDefault("nap.do_log_compression", "false");
+  parameters_->SetDefault("nap.lowpass_cutoff", "1200.0");
+  parameters_->SetDefault("nap.lowpass_order", "2");
+
+  do_lowpass_ = parameters_->GetBool("nap.do_lowpass");
+  do_log_ = parameters_->GetBool("nap.do_log_compression");
+  lowpass_cutoff_ = parameters_->GetFloat("nap.lowpass_cutoff");
+  lowpass_order_ = parameters_->GetInt("nap.lowpass_order");
+}
+
+ModuleHCL::~ModuleHCL() {
+}
+
+bool ModuleHCL::InitializeInternal(const SignalBank &input) {
+  time_constant_ = 1.0f / (2.0f * M_PI * lowpass_cutoff_);
+  channel_count_ = input.channel_count();
+  output_.Initialize(input);
+  Reset();
+  return true;
+}
+
+void ModuleHCL::Reset() {
+  xn_ = 0.0f;
+  yn_ = 0.0f;
+  yns_.clear();
+  yns_.resize(channel_count_);
+  for (int c = 0; c < channel_count_; ++c) {
+    yns_[c].resize(lowpass_order_, 0.0f);
+  }
+}
+
+/* With do_log, the signal is first scaled up so that values <1.0 become
+ * negligible. This just rescales the sample values to fill the range of a
+ * 16-bit signed integer, then we lose the bottom bit of resolution. If the
+ * signal was sampled at 16-bit resolution, there shouldn't be anything to
+ * speak of there anyway. If it was sampled using a higher resolution, then
+ * some data will be discarded.
+ */
+void ModuleHCL::Process(const SignalBank &input) {
+  output_.set_start_time(input.start_time());
+  for (int c = 0; c < input.channel_count(); ++c) {
+    for (int i = 0; i < input.buffer_length(); ++i) {
+      if (input[c][i] < 0.0f) {
+        output_.set_sample(c, i, 0.0f);
+      } else {
+        float s = input[c][i];
+        if (do_log_) {
+          s *= pow(2.0f,15);
+          if (s < 1.0f) s = 1.0f;
+          s = 20.0f * log10(s);
+        }
+        output_.set_sample(c, i, s);
+      }
+    }
+    if (do_lowpass_) {
+      float b = exp( -1.0f / (input.sample_rate() * time_constant_));
+      float gain = 1.0f / (1.0f - b);
+      for (int j = 0; j < lowpass_order_; j++) {
+        for (int k = 0; k < output_.buffer_length(); ++k) {
+          xn_ = output_[c][k];
+          yn_ = xn_ + b * yns_[c][j];
+          yns_[c][j] = yn_;
+          output_.set_sample(c, k, yn_ / gain);
+        }
+      }
+    }
+  }
+  PushOutput();
+}
+}  // namespace aimc