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    size_t input_length,
22    size_t old_data_length,
23    AudioMultiVector* output,
24    size_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 size_t 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  const bool kFastMode = false;  // Fast mode is not available for PE Expand.
38  return TimeStretch::Process(input, input_length, kFastMode, output,
39                              length_change_samples);
40}
41
42void PreemptiveExpand::SetParametersForPassiveSpeech(size_t len,
43                                                     int16_t* best_correlation,
44                                                     size_t* peak_index) const {
45  // When the signal does not contain any active speech, the correlation does
46  // not matter. Simply set it to zero.
47  *best_correlation = 0;
48
49  // For low energy expansion, the new data can be less than 15 ms,
50  // but we must ensure that best_correlation is not larger than the length of
51  // the new data.
52  // but we must ensure that best_correlation is not larger than the new data.
53  *peak_index = std::min(*peak_index,
54                         len - old_data_length_per_channel_);
55}
56
57PreemptiveExpand::ReturnCodes PreemptiveExpand::CheckCriteriaAndStretch(
58    const int16_t* input,
59    size_t input_length,
60    size_t peak_index,
61    int16_t best_correlation,
62    bool active_speech,
63    bool /*fast_mode*/,
64    AudioMultiVector* output) const {
65  // Pre-calculate common multiplication with |fs_mult_|.
66  // 120 corresponds to 15 ms.
67  size_t fs_mult_120 = static_cast<size_t>(fs_mult_ * 120);
68  // Check for strong correlation (>0.9 in Q14) and at least 15 ms new data,
69  // or passive speech.
70  if (((best_correlation > kCorrelationThreshold) &&
71      (old_data_length_per_channel_ <= fs_mult_120)) ||
72      !active_speech) {
73    // Do accelerate operation by overlap add.
74
75    // Set length of the first part, not to be modified.
76    size_t unmodified_length = std::max(old_data_length_per_channel_,
77                                        fs_mult_120);
78    // Copy first part, including cross-fade region.
79    output->PushBackInterleaved(
80        input, (unmodified_length + peak_index) * num_channels_);
81    // Copy the last |peak_index| samples up to 15 ms to |temp_vector|.
82    AudioMultiVector temp_vector(num_channels_);
83    temp_vector.PushBackInterleaved(
84        &input[(unmodified_length - peak_index) * num_channels_],
85        peak_index * num_channels_);
86    // Cross-fade |temp_vector| onto the end of |output|.
87    output->CrossFade(temp_vector, peak_index);
88    // Copy the last unmodified part, 15 ms + pitch period until the end.
89    output->PushBackInterleaved(
90        &input[unmodified_length * num_channels_],
91        input_length - unmodified_length * num_channels_);
92
93    if (active_speech) {
94      return kSuccess;
95    } else {
96      return kSuccessLowEnergy;
97    }
98  } else {
99    // Accelerate not allowed. Simply move all data from decoded to outData.
100    output->PushBackInterleaved(input, input_length);
101    return kNoStretch;
102  }
103}
104
105PreemptiveExpand* PreemptiveExpandFactory::Create(
106    int sample_rate_hz,
107    size_t num_channels,
108    const BackgroundNoise& background_noise,
109    size_t overlap_samples) const {
110  return new PreemptiveExpand(
111      sample_rate_hz, num_channels, background_noise, overlap_samples);
112}
113
114}  // namespace webrtc
115