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 "modules/audio_coding/neteq/preemptive_expand.h"
12
13 #include <algorithm>
14
15 #include "api/array_view.h"
16 #include "modules/audio_coding/neteq/audio_multi_vector.h"
17 #include "modules/audio_coding/neteq/time_stretch.h"
18
19 namespace webrtc {
20
Process(const int16_t * input,size_t input_length,size_t old_data_length,AudioMultiVector * output,size_t * length_change_samples)21 PreemptiveExpand::ReturnCodes PreemptiveExpand::Process(
22 const int16_t* input,
23 size_t input_length,
24 size_t old_data_length,
25 AudioMultiVector* output,
26 size_t* length_change_samples) {
27 old_data_length_per_channel_ = old_data_length;
28 // Input length must be (almost) 30 ms.
29 // Also, the new part must be at least |overlap_samples_| elements.
30 static const size_t k15ms = 120; // 15 ms = 120 samples at 8 kHz sample rate.
31 if (num_channels_ == 0 ||
32 input_length / num_channels_ < (2 * k15ms - 1) * fs_mult_ ||
33 old_data_length >= input_length / num_channels_ - overlap_samples_) {
34 // Length of input data too short to do preemptive expand. Simply move all
35 // data from input to output.
36 output->PushBackInterleaved(
37 rtc::ArrayView<const int16_t>(input, input_length));
38 return kError;
39 }
40 const bool kFastMode = false; // Fast mode is not available for PE Expand.
41 return TimeStretch::Process(input, input_length, kFastMode, output,
42 length_change_samples);
43 }
44
SetParametersForPassiveSpeech(size_t len,int16_t * best_correlation,size_t * peak_index) const45 void PreemptiveExpand::SetParametersForPassiveSpeech(size_t len,
46 int16_t* best_correlation,
47 size_t* peak_index) const {
48 // When the signal does not contain any active speech, the correlation does
49 // not matter. Simply set it to zero.
50 *best_correlation = 0;
51
52 // For low energy expansion, the new data can be less than 15 ms,
53 // but we must ensure that best_correlation is not larger than the length of
54 // the new data.
55 // but we must ensure that best_correlation is not larger than the new data.
56 *peak_index = std::min(*peak_index, len - old_data_length_per_channel_);
57 }
58
CheckCriteriaAndStretch(const int16_t * input,size_t input_length,size_t peak_index,int16_t best_correlation,bool active_speech,bool,AudioMultiVector * output) const59 PreemptiveExpand::ReturnCodes PreemptiveExpand::CheckCriteriaAndStretch(
60 const int16_t* input,
61 size_t input_length,
62 size_t peak_index,
63 int16_t best_correlation,
64 bool active_speech,
65 bool /*fast_mode*/,
66 AudioMultiVector* output) const {
67 // Pre-calculate common multiplication with |fs_mult_|.
68 // 120 corresponds to 15 ms.
69 size_t fs_mult_120 = static_cast<size_t>(fs_mult_ * 120);
70 // Check for strong correlation (>0.9 in Q14) and at least 15 ms new data,
71 // or passive speech.
72 if (((best_correlation > kCorrelationThreshold) &&
73 (old_data_length_per_channel_ <= fs_mult_120)) ||
74 !active_speech) {
75 // Do accelerate operation by overlap add.
76
77 // Set length of the first part, not to be modified.
78 size_t unmodified_length =
79 std::max(old_data_length_per_channel_, fs_mult_120);
80 // Copy first part, including cross-fade region.
81 output->PushBackInterleaved(rtc::ArrayView<const int16_t>(
82 input, (unmodified_length + peak_index) * num_channels_));
83 // Copy the last |peak_index| samples up to 15 ms to |temp_vector|.
84 AudioMultiVector temp_vector(num_channels_);
85 temp_vector.PushBackInterleaved(rtc::ArrayView<const int16_t>(
86 &input[(unmodified_length - peak_index) * num_channels_],
87 peak_index * num_channels_));
88 // Cross-fade |temp_vector| onto the end of |output|.
89 output->CrossFade(temp_vector, peak_index);
90 // Copy the last unmodified part, 15 ms + pitch period until the end.
91 output->PushBackInterleaved(rtc::ArrayView<const int16_t>(
92 &input[unmodified_length * num_channels_],
93 input_length - unmodified_length * num_channels_));
94
95 if (active_speech) {
96 return kSuccess;
97 } else {
98 return kSuccessLowEnergy;
99 }
100 } else {
101 // Accelerate not allowed. Simply move all data from decoded to outData.
102 output->PushBackInterleaved(
103 rtc::ArrayView<const int16_t>(input, input_length));
104 return kNoStretch;
105 }
106 }
107
Create(int sample_rate_hz,size_t num_channels,const BackgroundNoise & background_noise,size_t overlap_samples) const108 PreemptiveExpand* PreemptiveExpandFactory::Create(
109 int sample_rate_hz,
110 size_t num_channels,
111 const BackgroundNoise& background_noise,
112 size_t overlap_samples) const {
113 return new PreemptiveExpand(sample_rate_hz, num_channels, background_noise,
114 overlap_samples);
115 }
116
117 } // namespace webrtc
118