1/*
2 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include "webrtc/modules/audio_coding/neteq/preemptive_expand.h"
12
13#include <algorithm>  // min, max
14
15#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
16
17namespace webrtc {
18
19PreemptiveExpand::ReturnCodes PreemptiveExpand::Process(
20    const int16_t* input,
21    int input_length,
22    int old_data_length,
23    AudioMultiVector* output,
24    int16_t* length_change_samples) {
25  old_data_length_per_channel_ = old_data_length;
26  // Input length must be (almost) 30 ms.
27  // Also, the new part must be at least |overlap_samples_| elements.
28  static const int k15ms = 120;  // 15 ms = 120 samples at 8 kHz sample rate.
29  if (num_channels_ == 0 ||
30      input_length / num_channels_ < (2 * k15ms - 1) * fs_mult_ ||
31      old_data_length >= input_length / num_channels_ - overlap_samples_) {
32    // Length of input data too short to do preemptive expand. Simply move all
33    // data from input to output.
34    output->PushBackInterleaved(input, input_length);
35    return kError;
36  }
37  return TimeStretch::Process(input, input_length, output,
38                              length_change_samples);
39}
40
41void PreemptiveExpand::SetParametersForPassiveSpeech(size_t len,
42                                                     int16_t* best_correlation,
43                                                     int* peak_index) const {
44  // When the signal does not contain any active speech, the correlation does
45  // not matter. Simply set it to zero.
46  *best_correlation = 0;
47
48  // For low energy expansion, the new data can be less than 15 ms,
49  // but we must ensure that best_correlation is not larger than the length of
50  // the new data.
51  // but we must ensure that best_correlation is not larger than the new data.
52  *peak_index = std::min(*peak_index,
53                         static_cast<int>(len - old_data_length_per_channel_));
54}
55
56PreemptiveExpand::ReturnCodes PreemptiveExpand::CheckCriteriaAndStretch(
57    const int16_t *input, size_t input_length, size_t peak_index,
58    int16_t best_correlation, bool active_speech,
59    AudioMultiVector* output) const {
60  // Pre-calculate common multiplication with |fs_mult_|.
61  // 120 corresponds to 15 ms.
62  int fs_mult_120 = fs_mult_ * 120;
63  assert(old_data_length_per_channel_ >= 0);  // Make sure it's been set.
64  // Check for strong correlation (>0.9 in Q14) and at least 15 ms new data,
65  // or passive speech.
66  if (((best_correlation > kCorrelationThreshold) &&
67      (old_data_length_per_channel_ <= fs_mult_120)) ||
68      !active_speech) {
69    // Do accelerate operation by overlap add.
70
71    // Set length of the first part, not to be modified.
72    size_t unmodified_length = std::max(old_data_length_per_channel_,
73                                        fs_mult_120);
74    // Copy first part, including cross-fade region.
75    output->PushBackInterleaved(
76        input, (unmodified_length + peak_index) * num_channels_);
77    // Copy the last |peak_index| samples up to 15 ms to |temp_vector|.
78    AudioMultiVector temp_vector(num_channels_);
79    temp_vector.PushBackInterleaved(
80        &input[(unmodified_length - peak_index) * num_channels_],
81        peak_index * num_channels_);
82    // Cross-fade |temp_vector| onto the end of |output|.
83    output->CrossFade(temp_vector, peak_index);
84    // Copy the last unmodified part, 15 ms + pitch period until the end.
85    output->PushBackInterleaved(
86        &input[unmodified_length * num_channels_],
87        input_length - unmodified_length * num_channels_);
88
89    if (active_speech) {
90      return kSuccess;
91    } else {
92      return kSuccessLowEnergy;
93    }
94  } else {
95    // Accelerate not allowed. Simply move all data from decoded to outData.
96    output->PushBackInterleaved(input, input_length);
97    return kNoStretch;
98  }
99}
100
101PreemptiveExpand* PreemptiveExpandFactory::Create(
102    int sample_rate_hz,
103    size_t num_channels,
104    const BackgroundNoise& background_noise,
105    int overlap_samples) const {
106  return new PreemptiveExpand(
107      sample_rate_hz, num_channels, background_noise, overlap_samples);
108}
109
110}  // namespace webrtc
111