QUIC - use size_t for kMaxInitialRoundTripTimeUs.
[chromium-blink-merge.git] / media / base / channel_mixer.cc
blob3de63fe8bf1582a947d3e82c2fe330c823d5c267
1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 // MSVC++ requires this to be set before any other includes to get M_SQRT1_2.
6 #define _USE_MATH_DEFINES
8 #include "media/base/channel_mixer.h"
10 #include <algorithm>
11 #include <cmath>
13 #include "base/logging.h"
14 #include "media/audio/audio_parameters.h"
15 #include "media/base/audio_bus.h"
16 #include "media/base/vector_math.h"
18 namespace media {
20 // Default scale factor for mixing two channels together. We use a different
21 // value for stereo -> mono and mono -> stereo mixes.
22 static const float kEqualPowerScale = static_cast<float>(M_SQRT1_2);
24 static void ValidateLayout(ChannelLayout layout) {
25 CHECK_NE(layout, CHANNEL_LAYOUT_NONE);
26 CHECK_NE(layout, CHANNEL_LAYOUT_MAX);
27 CHECK_NE(layout, CHANNEL_LAYOUT_UNSUPPORTED);
28 CHECK_NE(layout, CHANNEL_LAYOUT_DISCRETE);
30 // Verify there's at least one channel. Should always be true here by virtue
31 // of not being one of the invalid layouts, but lets double check to be sure.
32 int channel_count = ChannelLayoutToChannelCount(layout);
33 DCHECK_GT(channel_count, 0);
35 // If we have more than one channel, verify a symmetric layout for sanity.
36 // The unit test will verify all possible layouts, so this can be a DCHECK.
37 // Symmetry allows simplifying the matrix building code by allowing us to
38 // assume that if one channel of a pair exists, the other will too.
39 if (channel_count > 1) {
40 DCHECK((ChannelOrder(layout, LEFT) >= 0 &&
41 ChannelOrder(layout, RIGHT) >= 0) ||
42 (ChannelOrder(layout, SIDE_LEFT) >= 0 &&
43 ChannelOrder(layout, SIDE_RIGHT) >= 0) ||
44 (ChannelOrder(layout, BACK_LEFT) >= 0 &&
45 ChannelOrder(layout, BACK_RIGHT) >= 0) ||
46 (ChannelOrder(layout, LEFT_OF_CENTER) >= 0 &&
47 ChannelOrder(layout, RIGHT_OF_CENTER) >= 0))
48 << "Non-symmetric channel layout encountered.";
49 } else {
50 DCHECK_EQ(layout, CHANNEL_LAYOUT_MONO);
53 return;
56 class MatrixBuilder {
57 public:
58 MatrixBuilder(ChannelLayout input_layout, int input_channels,
59 ChannelLayout output_layout, int output_channels)
60 : input_layout_(input_layout),
61 input_channels_(input_channels),
62 output_layout_(output_layout),
63 output_channels_(output_channels) {
64 // Special case for 5.0, 5.1 with back channels when upmixed to 7.0, 7.1,
65 // which should map the back LR to side LR.
66 if (input_layout_ == CHANNEL_LAYOUT_5_0_BACK &&
67 output_layout_ == CHANNEL_LAYOUT_7_0) {
68 input_layout_ = CHANNEL_LAYOUT_5_0;
69 } else if (input_layout_ == CHANNEL_LAYOUT_5_1_BACK &&
70 output_layout_ == CHANNEL_LAYOUT_7_1) {
71 input_layout_ = CHANNEL_LAYOUT_5_1;
75 ~MatrixBuilder() { }
77 // Create the transformation matrix of input channels to output channels.
78 // Updates the empty matrix with the transformation, and returns true
79 // if the transformation is just a remapping of channels (no mixing).
80 bool CreateTransformationMatrix(std::vector< std::vector<float> >* matrix);
82 private:
83 // Result transformation of input channels to output channels
84 std::vector< std::vector<float> >* matrix_;
86 // Input and output channel layout provided during construction.
87 ChannelLayout input_layout_;
88 int input_channels_;
89 ChannelLayout output_layout_;
90 int output_channels_;
92 // Helper variable for tracking which inputs are currently unaccounted,
93 // should be empty after construction completes.
94 std::vector<Channels> unaccounted_inputs_;
96 // Helper methods for managing unaccounted input channels.
97 void AccountFor(Channels ch);
98 bool IsUnaccounted(Channels ch);
100 // Helper methods for checking if |ch| exists in either |input_layout_| or
101 // |output_layout_| respectively.
102 bool HasInputChannel(Channels ch);
103 bool HasOutputChannel(Channels ch);
105 // Helper methods for updating |matrix_| with the proper value for
106 // mixing |input_ch| into |output_ch|. MixWithoutAccounting() does not
107 // remove the channel from |unaccounted_inputs_|.
108 void Mix(Channels input_ch, Channels output_ch, float scale);
109 void MixWithoutAccounting(Channels input_ch, Channels output_ch,
110 float scale);
112 DISALLOW_COPY_AND_ASSIGN(MatrixBuilder);
115 ChannelMixer::ChannelMixer(ChannelLayout input_layout,
116 ChannelLayout output_layout) {
117 Initialize(input_layout,
118 ChannelLayoutToChannelCount(input_layout),
119 output_layout,
120 ChannelLayoutToChannelCount(output_layout));
123 ChannelMixer::ChannelMixer(
124 const AudioParameters& input, const AudioParameters& output) {
125 Initialize(input.channel_layout(),
126 input.channels(),
127 output.channel_layout(),
128 output.channels());
131 void ChannelMixer::Initialize(
132 ChannelLayout input_layout, int input_channels,
133 ChannelLayout output_layout, int output_channels) {
134 // Stereo down mix should never be the output layout.
135 CHECK_NE(output_layout, CHANNEL_LAYOUT_STEREO_DOWNMIX);
137 // Verify that the layouts are supported
138 if (input_layout != CHANNEL_LAYOUT_DISCRETE)
139 ValidateLayout(input_layout);
140 if (output_layout != CHANNEL_LAYOUT_DISCRETE)
141 ValidateLayout(output_layout);
143 // Create the transformation matrix
144 MatrixBuilder matrix_builder(input_layout, input_channels,
145 output_layout, output_channels);
146 remapping_ = matrix_builder.CreateTransformationMatrix(&matrix_);
149 bool MatrixBuilder::CreateTransformationMatrix(
150 std::vector< std::vector<float> >* matrix) {
151 matrix_ = matrix;
153 // Size out the initial matrix.
154 matrix_->reserve(output_channels_);
155 for (int output_ch = 0; output_ch < output_channels_; ++output_ch)
156 matrix_->push_back(std::vector<float>(input_channels_, 0));
158 // First check for discrete case.
159 if (input_layout_ == CHANNEL_LAYOUT_DISCRETE ||
160 output_layout_ == CHANNEL_LAYOUT_DISCRETE) {
161 // If the number of input channels is more than output channels, then
162 // copy as many as we can then drop the remaining input channels.
163 // If the number of input channels is less than output channels, then
164 // copy them all, then zero out the remaining output channels.
165 int passthrough_channels = std::min(input_channels_, output_channels_);
166 for (int i = 0; i < passthrough_channels; ++i)
167 (*matrix_)[i][i] = 1;
169 return true;
172 // Route matching channels and figure out which ones aren't accounted for.
173 for (Channels ch = LEFT; ch < CHANNELS_MAX;
174 ch = static_cast<Channels>(ch + 1)) {
175 int input_ch_index = ChannelOrder(input_layout_, ch);
176 if (input_ch_index < 0)
177 continue;
179 int output_ch_index = ChannelOrder(output_layout_, ch);
180 if (output_ch_index < 0) {
181 unaccounted_inputs_.push_back(ch);
182 continue;
185 DCHECK_LT(static_cast<size_t>(output_ch_index), matrix_->size());
186 DCHECK_LT(static_cast<size_t>(input_ch_index),
187 (*matrix_)[output_ch_index].size());
188 (*matrix_)[output_ch_index][input_ch_index] = 1;
191 // If all input channels are accounted for, there's nothing left to do.
192 if (unaccounted_inputs_.empty()) {
193 // Since all output channels map directly to inputs we can optimize.
194 return true;
197 // Mix front LR into center.
198 if (IsUnaccounted(LEFT)) {
199 // When down mixing to mono from stereo, we need to be careful of full scale
200 // stereo mixes. Scaling by 1 / sqrt(2) here will likely lead to clipping
201 // so we use 1 / 2 instead.
202 float scale =
203 (output_layout_ == CHANNEL_LAYOUT_MONO && input_channels_ == 2) ?
204 0.5 : kEqualPowerScale;
205 Mix(LEFT, CENTER, scale);
206 Mix(RIGHT, CENTER, scale);
209 // Mix center into front LR.
210 if (IsUnaccounted(CENTER)) {
211 // When up mixing from mono, just do a copy to front LR.
212 float scale =
213 (input_layout_ == CHANNEL_LAYOUT_MONO) ? 1 : kEqualPowerScale;
214 MixWithoutAccounting(CENTER, LEFT, scale);
215 Mix(CENTER, RIGHT, scale);
218 // Mix back LR into: side LR || back center || front LR || front center.
219 if (IsUnaccounted(BACK_LEFT)) {
220 if (HasOutputChannel(SIDE_LEFT)) {
221 // If we have side LR, mix back LR into side LR, but instead if the input
222 // doesn't have side LR (but output does) copy back LR to side LR.
223 float scale = HasInputChannel(SIDE_LEFT) ? kEqualPowerScale : 1;
224 Mix(BACK_LEFT, SIDE_LEFT, scale);
225 Mix(BACK_RIGHT, SIDE_RIGHT, scale);
226 } else if (HasOutputChannel(BACK_CENTER)) {
227 // Mix back LR into back center.
228 Mix(BACK_LEFT, BACK_CENTER, kEqualPowerScale);
229 Mix(BACK_RIGHT, BACK_CENTER, kEqualPowerScale);
230 } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
231 // Mix back LR into front LR.
232 Mix(BACK_LEFT, LEFT, kEqualPowerScale);
233 Mix(BACK_RIGHT, RIGHT, kEqualPowerScale);
234 } else {
235 // Mix back LR into front center.
236 Mix(BACK_LEFT, CENTER, kEqualPowerScale);
237 Mix(BACK_RIGHT, CENTER, kEqualPowerScale);
241 // Mix side LR into: back LR || back center || front LR || front center.
242 if (IsUnaccounted(SIDE_LEFT)) {
243 if (HasOutputChannel(BACK_LEFT)) {
244 // If we have back LR, mix side LR into back LR, but instead if the input
245 // doesn't have back LR (but output does) copy side LR to back LR.
246 float scale = HasInputChannel(BACK_LEFT) ? kEqualPowerScale : 1;
247 Mix(SIDE_LEFT, BACK_LEFT, scale);
248 Mix(SIDE_RIGHT, BACK_RIGHT, scale);
249 } else if (HasOutputChannel(BACK_CENTER)) {
250 // Mix side LR into back center.
251 Mix(SIDE_LEFT, BACK_CENTER, kEqualPowerScale);
252 Mix(SIDE_RIGHT, BACK_CENTER, kEqualPowerScale);
253 } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
254 // Mix side LR into front LR.
255 Mix(SIDE_LEFT, LEFT, kEqualPowerScale);
256 Mix(SIDE_RIGHT, RIGHT, kEqualPowerScale);
257 } else {
258 // Mix side LR into front center.
259 Mix(SIDE_LEFT, CENTER, kEqualPowerScale);
260 Mix(SIDE_RIGHT, CENTER, kEqualPowerScale);
264 // Mix back center into: back LR || side LR || front LR || front center.
265 if (IsUnaccounted(BACK_CENTER)) {
266 if (HasOutputChannel(BACK_LEFT)) {
267 // Mix back center into back LR.
268 MixWithoutAccounting(BACK_CENTER, BACK_LEFT, kEqualPowerScale);
269 Mix(BACK_CENTER, BACK_RIGHT, kEqualPowerScale);
270 } else if (HasOutputChannel(SIDE_LEFT)) {
271 // Mix back center into side LR.
272 MixWithoutAccounting(BACK_CENTER, SIDE_LEFT, kEqualPowerScale);
273 Mix(BACK_CENTER, SIDE_RIGHT, kEqualPowerScale);
274 } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
275 // Mix back center into front LR.
276 // TODO(dalecurtis): Not sure about these values?
277 MixWithoutAccounting(BACK_CENTER, LEFT, kEqualPowerScale);
278 Mix(BACK_CENTER, RIGHT, kEqualPowerScale);
279 } else {
280 // Mix back center into front center.
281 // TODO(dalecurtis): Not sure about these values?
282 Mix(BACK_CENTER, CENTER, kEqualPowerScale);
286 // Mix LR of center into: front center || front LR.
287 if (IsUnaccounted(LEFT_OF_CENTER)) {
288 if (HasOutputChannel(LEFT)) {
289 // Mix LR of center into front LR.
290 Mix(LEFT_OF_CENTER, LEFT, kEqualPowerScale);
291 Mix(RIGHT_OF_CENTER, RIGHT, kEqualPowerScale);
292 } else {
293 // Mix LR of center into front center.
294 Mix(LEFT_OF_CENTER, CENTER, kEqualPowerScale);
295 Mix(RIGHT_OF_CENTER, CENTER, kEqualPowerScale);
299 // Mix LFE into: front LR || front center.
300 if (IsUnaccounted(LFE)) {
301 if (!HasOutputChannel(CENTER)) {
302 // Mix LFE into front LR.
303 MixWithoutAccounting(LFE, LEFT, kEqualPowerScale);
304 Mix(LFE, RIGHT, kEqualPowerScale);
305 } else {
306 // Mix LFE into front center.
307 Mix(LFE, CENTER, kEqualPowerScale);
311 // All channels should now be accounted for.
312 DCHECK(unaccounted_inputs_.empty());
314 // See if the output |matrix_| is simply a remapping matrix. If each input
315 // channel maps to a single output channel we can simply remap. Doing this
316 // programmatically is less fragile than logic checks on channel mappings.
317 for (int output_ch = 0; output_ch < output_channels_; ++output_ch) {
318 int input_mappings = 0;
319 for (int input_ch = 0; input_ch < input_channels_; ++input_ch) {
320 // We can only remap if each row contains a single scale of 1. I.e., each
321 // output channel is mapped from a single unscaled input channel.
322 if ((*matrix_)[output_ch][input_ch] != 1 || ++input_mappings > 1)
323 return false;
327 // If we've gotten here, |matrix_| is simply a remapping.
328 return true;
331 ChannelMixer::~ChannelMixer() {}
333 void ChannelMixer::Transform(const AudioBus* input, AudioBus* output) {
334 CHECK_EQ(matrix_.size(), static_cast<size_t>(output->channels()));
335 CHECK_EQ(matrix_[0].size(), static_cast<size_t>(input->channels()));
336 CHECK_EQ(input->frames(), output->frames());
338 // Zero initialize |output| so we're accumulating from zero.
339 output->Zero();
341 // If we're just remapping we can simply copy the correct input to output.
342 if (remapping_) {
343 for (int output_ch = 0; output_ch < output->channels(); ++output_ch) {
344 for (int input_ch = 0; input_ch < input->channels(); ++input_ch) {
345 float scale = matrix_[output_ch][input_ch];
346 if (scale > 0) {
347 DCHECK_EQ(scale, 1.0f);
348 memcpy(output->channel(output_ch), input->channel(input_ch),
349 sizeof(*output->channel(output_ch)) * output->frames());
350 break;
354 return;
357 for (int output_ch = 0; output_ch < output->channels(); ++output_ch) {
358 for (int input_ch = 0; input_ch < input->channels(); ++input_ch) {
359 float scale = matrix_[output_ch][input_ch];
360 // Scale should always be positive. Don't bother scaling by zero.
361 DCHECK_GE(scale, 0);
362 if (scale > 0) {
363 vector_math::FMAC(input->channel(input_ch), scale, output->frames(),
364 output->channel(output_ch));
370 void MatrixBuilder::AccountFor(Channels ch) {
371 unaccounted_inputs_.erase(std::find(
372 unaccounted_inputs_.begin(), unaccounted_inputs_.end(), ch));
375 bool MatrixBuilder::IsUnaccounted(Channels ch) {
376 return std::find(unaccounted_inputs_.begin(), unaccounted_inputs_.end(),
377 ch) != unaccounted_inputs_.end();
380 bool MatrixBuilder::HasInputChannel(Channels ch) {
381 return ChannelOrder(input_layout_, ch) >= 0;
384 bool MatrixBuilder::HasOutputChannel(Channels ch) {
385 return ChannelOrder(output_layout_, ch) >= 0;
388 void MatrixBuilder::Mix(Channels input_ch, Channels output_ch, float scale) {
389 MixWithoutAccounting(input_ch, output_ch, scale);
390 AccountFor(input_ch);
393 void MatrixBuilder::MixWithoutAccounting(Channels input_ch, Channels output_ch,
394 float scale) {
395 int input_ch_index = ChannelOrder(input_layout_, input_ch);
396 int output_ch_index = ChannelOrder(output_layout_, output_ch);
398 DCHECK(IsUnaccounted(input_ch));
399 DCHECK_GE(input_ch_index, 0);
400 DCHECK_GE(output_ch_index, 0);
402 DCHECK_EQ((*matrix_)[output_ch_index][input_ch_index], 0);
403 (*matrix_)[output_ch_index][input_ch_index] = scale;
406 } // namespace media