blocker.cc (8064B)
1 /* 2 * Copyright (c) 2014 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/codecs/opus/test/blocker.h" 12 13 #include <cstring> 14 15 #include "rtc_base/checks.h" 16 17 namespace { 18 19 // Adds `a` and `b` frame by frame into `result` (basically matrix addition). 20 void AddFrames(const float* const* a, 21 size_t a_start_index, 22 const float* const* b, 23 int b_start_index, 24 size_t num_frames, 25 size_t num_channels, 26 float* const* result, 27 size_t result_start_index) { 28 for (size_t i = 0; i < num_channels; ++i) { 29 for (size_t j = 0; j < num_frames; ++j) { 30 result[i][j + result_start_index] = 31 a[i][j + a_start_index] + b[i][j + b_start_index]; 32 } 33 } 34 } 35 36 // Copies `src` into `dst` channel by channel. 37 void CopyFrames(const float* const* src, 38 size_t src_start_index, 39 size_t num_frames, 40 size_t num_channels, 41 float* const* dst, 42 size_t dst_start_index) { 43 for (size_t i = 0; i < num_channels; ++i) { 44 memcpy(&dst[i][dst_start_index], &src[i][src_start_index], 45 num_frames * sizeof(dst[i][dst_start_index])); 46 } 47 } 48 49 // Moves `src` into `dst` channel by channel. 50 void MoveFrames(const float* const* src, 51 size_t src_start_index, 52 size_t num_frames, 53 size_t num_channels, 54 float* const* dst, 55 size_t dst_start_index) { 56 for (size_t i = 0; i < num_channels; ++i) { 57 memmove(&dst[i][dst_start_index], &src[i][src_start_index], 58 num_frames * sizeof(dst[i][dst_start_index])); 59 } 60 } 61 62 void ZeroOut(float* const* buffer, 63 size_t starting_idx, 64 size_t num_frames, 65 size_t num_channels) { 66 for (size_t i = 0; i < num_channels; ++i) { 67 memset(&buffer[i][starting_idx], 0, 68 num_frames * sizeof(buffer[i][starting_idx])); 69 } 70 } 71 72 // Pointwise multiplies each channel of `frames` with `window`. Results are 73 // stored in `frames`. 74 void ApplyWindow(const float* window, 75 size_t num_frames, 76 size_t num_channels, 77 float* const* frames) { 78 for (size_t i = 0; i < num_channels; ++i) { 79 for (size_t j = 0; j < num_frames; ++j) { 80 frames[i][j] = frames[i][j] * window[j]; 81 } 82 } 83 } 84 85 size_t gcd(size_t a, size_t b) { 86 size_t tmp; 87 while (b) { 88 tmp = a; 89 a = b; 90 b = tmp % b; 91 } 92 return a; 93 } 94 95 } // namespace 96 97 namespace webrtc { 98 99 Blocker::Blocker(size_t chunk_size, 100 size_t block_size, 101 size_t num_input_channels, 102 size_t num_output_channels, 103 const float* window, 104 size_t shift_amount, 105 BlockerCallback* callback) 106 : chunk_size_(chunk_size), 107 block_size_(block_size), 108 num_input_channels_(num_input_channels), 109 num_output_channels_(num_output_channels), 110 initial_delay_(block_size_ - gcd(chunk_size, shift_amount)), 111 frame_offset_(0), 112 input_buffer_(num_input_channels_, chunk_size_ + initial_delay_), 113 output_buffer_(chunk_size_ + initial_delay_, num_output_channels_), 114 input_block_(block_size_, num_input_channels_), 115 output_block_(block_size_, num_output_channels_), 116 window_(new float[block_size_]), 117 shift_amount_(shift_amount), 118 callback_(callback) { 119 RTC_CHECK_LE(num_output_channels_, num_input_channels_); 120 RTC_CHECK_LE(shift_amount_, block_size_); 121 122 memcpy(window_.get(), window, block_size_ * sizeof(*window_.get())); 123 input_buffer_.MoveReadPositionBackward(initial_delay_); 124 } 125 126 Blocker::~Blocker() = default; 127 128 // When block_size < chunk_size the input and output buffers look like this: 129 // 130 // delay* chunk_size chunk_size + delay* 131 // buffer: <-------------|---------------------|---------------|> 132 // _a_ _b_ _c_ 133 // 134 // On each call to ProcessChunk(): 135 // 1. New input gets read into sections _b_ and _c_ of the input buffer. 136 // 2. We block starting from frame_offset. 137 // 3. We block until we reach a block `bl` that doesn't contain any frames 138 // from sections _a_ or _b_ of the input buffer. 139 // 4. We window the current block, fire the callback for processing, window 140 // again, and overlap/add to the output buffer. 141 // 5. We copy sections _a_ and _b_ of the output buffer into output. 142 // 6. For both the input and the output buffers, we copy section _c_ into 143 // section _a_. 144 // 7. We set the new frame_offset to be the difference between the first frame 145 // of `bl` and the border between sections _b_ and _c_. 146 // 147 // When block_size > chunk_size the input and output buffers look like this: 148 // 149 // chunk_size delay* chunk_size + delay* 150 // buffer: <-------------|---------------------|---------------|> 151 // _a_ _b_ _c_ 152 // 153 // On each call to ProcessChunk(): 154 // The procedure is the same as above, except for: 155 // 1. New input gets read into section _c_ of the input buffer. 156 // 3. We block until we reach a block `bl` that doesn't contain any frames 157 // from section _a_ of the input buffer. 158 // 5. We copy section _a_ of the output buffer into output. 159 // 6. For both the input and the output buffers, we copy sections _b_ and _c_ 160 // into section _a_ and _b_. 161 // 7. We set the new frame_offset to be the difference between the first frame 162 // of `bl` and the border between sections _a_ and _b_. 163 // 164 // * delay here refers to inintial_delay_ 165 // 166 // TODO(claguna): Look at using ring buffers to eliminate some copies. 167 void Blocker::ProcessChunk(const float* const* input, 168 size_t chunk_size, 169 size_t num_input_channels, 170 size_t num_output_channels, 171 float* const* output) { 172 RTC_CHECK_EQ(chunk_size, chunk_size_); 173 RTC_CHECK_EQ(num_input_channels, num_input_channels_); 174 RTC_CHECK_EQ(num_output_channels, num_output_channels_); 175 176 input_buffer_.Write(input, num_input_channels, chunk_size_); 177 size_t first_frame_in_block = frame_offset_; 178 179 // Loop through blocks. 180 while (first_frame_in_block < chunk_size_) { 181 input_buffer_.Read(input_block_.channels(), num_input_channels, 182 block_size_); 183 input_buffer_.MoveReadPositionBackward(block_size_ - shift_amount_); 184 185 ApplyWindow(window_.get(), block_size_, num_input_channels_, 186 input_block_.channels()); 187 callback_->ProcessBlock(input_block_.channels(), block_size_, 188 num_input_channels_, num_output_channels_, 189 output_block_.channels()); 190 ApplyWindow(window_.get(), block_size_, num_output_channels_, 191 output_block_.channels()); 192 193 AddFrames(output_buffer_.channels(), first_frame_in_block, 194 output_block_.channels(), 0, block_size_, num_output_channels_, 195 output_buffer_.channels(), first_frame_in_block); 196 197 first_frame_in_block += shift_amount_; 198 } 199 200 // Copy output buffer to output 201 CopyFrames(output_buffer_.channels(), 0, chunk_size_, num_output_channels_, 202 output, 0); 203 204 // Copy output buffer [chunk_size_, chunk_size_ + initial_delay] 205 // to output buffer [0, initial_delay], zero the rest. 206 MoveFrames(output_buffer_.channels(), chunk_size, initial_delay_, 207 num_output_channels_, output_buffer_.channels(), 0); 208 ZeroOut(output_buffer_.channels(), initial_delay_, chunk_size_, 209 num_output_channels_); 210 211 // Calculate new starting frames. 212 frame_offset_ = first_frame_in_block - chunk_size_; 213 } 214 215 } // namespace webrtc