comfort_noise.cc (5144B)
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/comfort_noise.h" 12 13 #include <cstddef> 14 #include <cstdint> 15 #include <memory> 16 17 #include "api/array_view.h" 18 #include "modules/audio_coding/codecs/cng/webrtc_cng.h" 19 #include "modules/audio_coding/neteq/audio_multi_vector.h" 20 #include "modules/audio_coding/neteq/audio_vector.h" 21 #include "modules/audio_coding/neteq/decoder_database.h" 22 #include "modules/audio_coding/neteq/dsp_helper.h" 23 #include "modules/audio_coding/neteq/sync_buffer.h" 24 #include "rtc_base/checks.h" 25 #include "rtc_base/logging.h" 26 27 namespace webrtc { 28 29 void ComfortNoise::Reset() { 30 first_call_ = true; 31 } 32 33 int ComfortNoise::UpdateParameters(const Packet& packet) { 34 // Get comfort noise decoder. 35 if (decoder_database_->SetActiveCngDecoder(packet.payload_type) != kOK) { 36 return kUnknownPayloadType; 37 } 38 ComfortNoiseDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder(); 39 RTC_DCHECK(cng_decoder); 40 cng_decoder->UpdateSid(packet.payload); 41 return kOK; 42 } 43 44 int ComfortNoise::Generate(size_t requested_length, AudioMultiVector* output) { 45 // TODO(hlundin): Change to an enumerator and skip assert. 46 RTC_DCHECK(fs_hz_ == 8000 || fs_hz_ == 16000 || fs_hz_ == 32000 || 47 fs_hz_ == 48000); 48 // Not adapted for multi-channel yet. 49 if (output->Channels() != 1) { 50 RTC_LOG(LS_ERROR) << "No multi-channel support"; 51 return kMultiChannelNotSupported; 52 } 53 54 size_t number_of_samples = requested_length; 55 bool new_period = false; 56 if (first_call_) { 57 // Generate noise and overlap slightly with old data. 58 number_of_samples = requested_length + overlap_length_; 59 new_period = true; 60 } 61 output->AssertSize(number_of_samples); 62 // Get the decoder from the database. 63 ComfortNoiseDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder(); 64 if (!cng_decoder) { 65 RTC_LOG(LS_ERROR) << "Unknwown payload type"; 66 return kUnknownPayloadType; 67 } 68 69 std::unique_ptr<int16_t[]> temp(new int16_t[number_of_samples]); 70 if (!cng_decoder->Generate(ArrayView<int16_t>(temp.get(), number_of_samples), 71 new_period)) { 72 // Error returned. 73 output->Zeros(requested_length); 74 RTC_LOG(LS_ERROR) 75 << "ComfortNoiseDecoder::Genererate failed to generate comfort noise"; 76 return kInternalError; 77 } 78 (*output)[0].OverwriteAt(temp.get(), number_of_samples, 0); 79 80 if (first_call_) { 81 // Set tapering window parameters. Values are in Q15. 82 int16_t muting_window; // Mixing factor for overlap data. 83 int16_t muting_window_increment; // Mixing factor increment (negative). 84 int16_t unmuting_window; // Mixing factor for comfort noise. 85 int16_t unmuting_window_increment; // Mixing factor increment. 86 if (fs_hz_ == 8000) { 87 muting_window = DspHelper::kMuteFactorStart8kHz; 88 muting_window_increment = DspHelper::kMuteFactorIncrement8kHz; 89 unmuting_window = DspHelper::kUnmuteFactorStart8kHz; 90 unmuting_window_increment = DspHelper::kUnmuteFactorIncrement8kHz; 91 } else if (fs_hz_ == 16000) { 92 muting_window = DspHelper::kMuteFactorStart16kHz; 93 muting_window_increment = DspHelper::kMuteFactorIncrement16kHz; 94 unmuting_window = DspHelper::kUnmuteFactorStart16kHz; 95 unmuting_window_increment = DspHelper::kUnmuteFactorIncrement16kHz; 96 } else if (fs_hz_ == 32000) { 97 muting_window = DspHelper::kMuteFactorStart32kHz; 98 muting_window_increment = DspHelper::kMuteFactorIncrement32kHz; 99 unmuting_window = DspHelper::kUnmuteFactorStart32kHz; 100 unmuting_window_increment = DspHelper::kUnmuteFactorIncrement32kHz; 101 } else { // fs_hz_ == 48000 102 muting_window = DspHelper::kMuteFactorStart48kHz; 103 muting_window_increment = DspHelper::kMuteFactorIncrement48kHz; 104 unmuting_window = DspHelper::kUnmuteFactorStart48kHz; 105 unmuting_window_increment = DspHelper::kUnmuteFactorIncrement48kHz; 106 } 107 108 // Do overlap-add between new vector and overlap. 109 size_t start_ix = sync_buffer_->Size() - overlap_length_; 110 for (size_t i = 0; i < overlap_length_; i++) { 111 /* overlapVec[i] = WinMute * overlapVec[i] + WinUnMute * outData[i] */ 112 // The expression (*output)[0][i] is the i-th element in the first 113 // channel. 114 (*sync_buffer_)[0][start_ix + i] = 115 (((*sync_buffer_)[0][start_ix + i] * muting_window) + 116 ((*output)[0][i] * unmuting_window) + 16384) >> 117 15; 118 muting_window += muting_window_increment; 119 unmuting_window += unmuting_window_increment; 120 } 121 // Remove `overlap_length_` samples from the front of `output` since they 122 // were mixed into `sync_buffer_` above. 123 output->PopFront(overlap_length_); 124 } 125 first_call_ = false; 126 return kOK; 127 } 128 129 } // namespace webrtc