Rename neteq4 folder to neteq

Keep the old neteq4/audio_decoder_unittests.isolate while waiting for
a hard-coded reference to change.

This CL effectively reverts r6257 "Rename neteq4 folder to neteq".

BUG=2996
TBR=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/21629004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6367 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq/accelerate.cc b/webrtc/modules/audio_coding/neteq/accelerate.cc
new file mode 100644
index 0000000..6acd778
--- /dev/null
+++ b/webrtc/modules/audio_coding/neteq/accelerate.cc
@@ -0,0 +1,88 @@
+/*
+ *  Copyright (c) 2012 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/audio_coding/neteq/accelerate.h"
+
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
+
+namespace webrtc {
+
+Accelerate::ReturnCodes Accelerate::Process(
+    const int16_t* input,
+    size_t input_length,
+    AudioMultiVector* output,
+    int16_t* length_change_samples) {
+  // Input length must be (almost) 30 ms.
+  static const int k15ms = 120;  // 15 ms = 120 samples at 8 kHz sample rate.
+  if (num_channels_ == 0 || static_cast<int>(input_length) / num_channels_ <
+      (2 * k15ms - 1) * fs_mult_) {
+    // Length of input data too short to do accelerate. Simply move all data
+    // from input to output.
+    output->PushBackInterleaved(input, input_length);
+    return kError;
+  }
+  return TimeStretch::Process(input, input_length, output,
+                              length_change_samples);
+}
+
+void Accelerate::SetParametersForPassiveSpeech(size_t /*len*/,
+                                               int16_t* best_correlation,
+                                               int* /*peak_index*/) const {
+  // When the signal does not contain any active speech, the correlation does
+  // not matter. Simply set it to zero.
+  *best_correlation = 0;
+}
+
+Accelerate::ReturnCodes Accelerate::CheckCriteriaAndStretch(
+    const int16_t* input, size_t input_length, size_t peak_index,
+    int16_t best_correlation, bool active_speech,
+    AudioMultiVector* output) const {
+  // Check for strong correlation or passive speech.
+  if ((best_correlation > kCorrelationThreshold) || !active_speech) {
+    // Do accelerate operation by overlap add.
+
+    // Pre-calculate common multiplication with |fs_mult_|.
+    // 120 corresponds to 15 ms.
+    size_t fs_mult_120 = fs_mult_ * 120;
+
+    assert(fs_mult_120 >= peak_index);  // Should be handled in Process().
+    // Copy first part; 0 to 15 ms.
+    output->PushBackInterleaved(input, fs_mult_120 * num_channels_);
+    // Copy the |peak_index| starting at 15 ms to |temp_vector|.
+    AudioMultiVector temp_vector(num_channels_);
+    temp_vector.PushBackInterleaved(&input[fs_mult_120 * num_channels_],
+                                    peak_index * num_channels_);
+    // Cross-fade |temp_vector| onto the end of |output|.
+    output->CrossFade(temp_vector, peak_index);
+    // Copy the last unmodified part, 15 ms + pitch period until the end.
+    output->PushBackInterleaved(
+        &input[(fs_mult_120 + peak_index) * num_channels_],
+        input_length - (fs_mult_120 + peak_index) * num_channels_);
+
+    if (active_speech) {
+      return kSuccess;
+    } else {
+      return kSuccessLowEnergy;
+    }
+  } else {
+    // Accelerate not allowed. Simply move all data from decoded to outData.
+    output->PushBackInterleaved(input, input_length);
+    return kNoStretch;
+  }
+}
+
+Accelerate* AccelerateFactory::Create(
+    int sample_rate_hz,
+    size_t num_channels,
+    const BackgroundNoise& background_noise) const {
+  return new Accelerate(sample_rate_hz, num_channels, background_noise);
+}
+
+}  // namespace webrtc