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 17 namespace webrtc { 18 19 PreemptiveExpand::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 41 void 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 56 PreemptiveExpand::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 } 100 101 PreemptiveExpand* 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
