1 /*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include "config.h"
30
31 #if ENABLE(WEB_AUDIO)
32
33 #include "platform/audio/HRTFElevation.h"
34
35 #include <math.h>
36 #include <algorithm>
37 #include "platform/audio/AudioBus.h"
38 #include "platform/audio/HRTFPanner.h"
39 #include "wtf/ThreadingPrimitives.h"
40 #include "wtf/text/StringHash.h"
41
42 namespace blink {
43
44 const unsigned HRTFElevation::AzimuthSpacing = 15;
45 const unsigned HRTFElevation::NumberOfRawAzimuths = 360 / AzimuthSpacing;
46 const unsigned HRTFElevation::InterpolationFactor = 8;
47 const unsigned HRTFElevation::NumberOfTotalAzimuths = NumberOfRawAzimuths * InterpolationFactor;
48
49 // Total number of components of an HRTF database.
50 const size_t TotalNumberOfResponses = 240;
51
52 // Number of frames in an individual impulse response.
53 const size_t ResponseFrameSize = 256;
54
55 // Sample-rate of the spatialization impulse responses as stored in the resource file.
56 // The impulse responses may be resampled to a different sample-rate (depending on the audio hardware) when they are loaded.
57 const float ResponseSampleRate = 44100;
58
59 #if USE(CONCATENATED_IMPULSE_RESPONSES)
60
61 // This table maps the index into the elevation table with the corresponding angle. See
62 // https://bugs.webkit.org/show_bug.cgi?id=98294#c9 for the elevation angles and their order in the
63 // concatenated response.
64 const int ElevationIndexTableSize = 10;
65 const int ElevationIndexTable[ElevationIndexTableSize] = {
66 0, 15, 30, 45, 60, 75, 90, 315, 330, 345
67 };
68
69 // Lazily load a concatenated HRTF database for given subject and store it in a
70 // local hash table to ensure quick efficient future retrievals.
getConcatenatedImpulseResponsesForSubject(const String & subjectName)71 static PassRefPtr<AudioBus> getConcatenatedImpulseResponsesForSubject(const String& subjectName)
72 {
73 typedef HashMap<String, RefPtr<AudioBus> > AudioBusMap;
74 DEFINE_STATIC_LOCAL(AudioBusMap, audioBusMap, ());
75 DEFINE_STATIC_LOCAL(Mutex, mutex, ());
76
77 MutexLocker locker(mutex);
78 RefPtr<AudioBus> bus;
79 AudioBusMap::iterator iterator = audioBusMap.find(subjectName);
80 if (iterator == audioBusMap.end()) {
81 RefPtr<AudioBus> concatenatedImpulseResponses(AudioBus::loadPlatformResource(subjectName.utf8().data(), ResponseSampleRate));
82 ASSERT(concatenatedImpulseResponses);
83 if (!concatenatedImpulseResponses)
84 return nullptr;
85
86 bus = concatenatedImpulseResponses;
87 audioBusMap.set(subjectName, bus);
88 } else
89 bus = iterator->value;
90
91 size_t responseLength = bus->length();
92 size_t expectedLength = static_cast<size_t>(TotalNumberOfResponses * ResponseFrameSize);
93
94 // Check number of channels and length. For now these are fixed and known.
95 bool isBusGood = responseLength == expectedLength && bus->numberOfChannels() == 2;
96 ASSERT(isBusGood);
97 if (!isBusGood)
98 return nullptr;
99
100 return bus;
101 }
102 #endif
103
calculateKernelsForAzimuthElevation(int azimuth,int elevation,float sampleRate,const String & subjectName,RefPtr<HRTFKernel> & kernelL,RefPtr<HRTFKernel> & kernelR)104 bool HRTFElevation::calculateKernelsForAzimuthElevation(int azimuth, int elevation, float sampleRate, const String& subjectName,
105 RefPtr<HRTFKernel>& kernelL, RefPtr<HRTFKernel>& kernelR)
106 {
107 // Valid values for azimuth are 0 -> 345 in 15 degree increments.
108 // Valid values for elevation are -45 -> +90 in 15 degree increments.
109
110 bool isAzimuthGood = azimuth >= 0 && azimuth <= 345 && (azimuth / 15) * 15 == azimuth;
111 ASSERT(isAzimuthGood);
112 if (!isAzimuthGood)
113 return false;
114
115 bool isElevationGood = elevation >= -45 && elevation <= 90 && (elevation / 15) * 15 == elevation;
116 ASSERT(isElevationGood);
117 if (!isElevationGood)
118 return false;
119
120 // Construct the resource name from the subject name, azimuth, and elevation, for example:
121 // "IRC_Composite_C_R0195_T015_P000"
122 // Note: the passed in subjectName is not a string passed in via JavaScript or the web.
123 // It's passed in as an internal ASCII identifier and is an implementation detail.
124 int positiveElevation = elevation < 0 ? elevation + 360 : elevation;
125
126 #if USE(CONCATENATED_IMPULSE_RESPONSES)
127 RefPtr<AudioBus> bus(getConcatenatedImpulseResponsesForSubject(subjectName));
128
129 if (!bus)
130 return false;
131
132 // Just sequentially search the table to find the correct index.
133 int elevationIndex = -1;
134
135 for (int k = 0; k < ElevationIndexTableSize; ++k) {
136 if (ElevationIndexTable[k] == positiveElevation) {
137 elevationIndex = k;
138 break;
139 }
140 }
141
142 bool isElevationIndexGood = (elevationIndex >= 0) && (elevationIndex < ElevationIndexTableSize);
143 ASSERT(isElevationIndexGood);
144 if (!isElevationIndexGood)
145 return false;
146
147 // The concatenated impulse response is a bus containing all
148 // the elevations per azimuth, for all azimuths by increasing
149 // order. So for a given azimuth and elevation we need to compute
150 // the index of the wanted audio frames in the concatenated table.
151 unsigned index = ((azimuth / AzimuthSpacing) * HRTFDatabase::NumberOfRawElevations) + elevationIndex;
152 bool isIndexGood = index < TotalNumberOfResponses;
153 ASSERT(isIndexGood);
154 if (!isIndexGood)
155 return false;
156
157 // Extract the individual impulse response from the concatenated
158 // responses and potentially sample-rate convert it to the desired
159 // (hardware) sample-rate.
160 unsigned startFrame = index * ResponseFrameSize;
161 unsigned stopFrame = startFrame + ResponseFrameSize;
162 RefPtr<AudioBus> preSampleRateConvertedResponse(AudioBus::createBufferFromRange(bus.get(), startFrame, stopFrame));
163 RefPtr<AudioBus> response(AudioBus::createBySampleRateConverting(preSampleRateConvertedResponse.get(), false, sampleRate));
164 AudioChannel* leftEarImpulseResponse = response->channel(AudioBus::ChannelLeft);
165 AudioChannel* rightEarImpulseResponse = response->channel(AudioBus::ChannelRight);
166 #else
167 String resourceName = String::format("IRC_%s_C_R0195_T%03d_P%03d", subjectName.utf8().data(), azimuth, positiveElevation);
168
169 RefPtr<AudioBus> impulseResponse(AudioBus::loadPlatformResource(resourceName.utf8().data(), sampleRate));
170
171 ASSERT(impulseResponse.get());
172 if (!impulseResponse.get())
173 return false;
174
175 size_t responseLength = impulseResponse->length();
176 size_t expectedLength = static_cast<size_t>(256 * (sampleRate / 44100.0));
177
178 // Check number of channels and length. For now these are fixed and known.
179 bool isBusGood = responseLength == expectedLength && impulseResponse->numberOfChannels() == 2;
180 ASSERT(isBusGood);
181 if (!isBusGood)
182 return false;
183
184 AudioChannel* leftEarImpulseResponse = impulseResponse->channelByType(AudioBus::ChannelLeft);
185 AudioChannel* rightEarImpulseResponse = impulseResponse->channelByType(AudioBus::ChannelRight);
186 #endif
187
188 // Note that depending on the fftSize returned by the panner, we may be truncating the impulse response we just loaded in.
189 const size_t fftSize = HRTFPanner::fftSizeForSampleRate(sampleRate);
190 kernelL = HRTFKernel::create(leftEarImpulseResponse, fftSize, sampleRate);
191 kernelR = HRTFKernel::create(rightEarImpulseResponse, fftSize, sampleRate);
192
193 return true;
194 }
195
196 // The range of elevations for the IRCAM impulse responses varies depending on azimuth, but the minimum elevation appears to always be -45.
197 //
198 // Here's how it goes:
199 static int maxElevations[] = {
200 // Azimuth
201 //
202 90, // 0
203 45, // 15
204 60, // 30
205 45, // 45
206 75, // 60
207 45, // 75
208 60, // 90
209 45, // 105
210 75, // 120
211 45, // 135
212 60, // 150
213 45, // 165
214 75, // 180
215 45, // 195
216 60, // 210
217 45, // 225
218 75, // 240
219 45, // 255
220 60, // 270
221 45, // 285
222 75, // 300
223 45, // 315
224 60, // 330
225 45 // 345
226 };
227
createForSubject(const String & subjectName,int elevation,float sampleRate)228 PassOwnPtr<HRTFElevation> HRTFElevation::createForSubject(const String& subjectName, int elevation, float sampleRate)
229 {
230 bool isElevationGood = elevation >= -45 && elevation <= 90 && (elevation / 15) * 15 == elevation;
231 ASSERT(isElevationGood);
232 if (!isElevationGood)
233 return nullptr;
234
235 OwnPtr<HRTFKernelList> kernelListL = adoptPtr(new HRTFKernelList(NumberOfTotalAzimuths));
236 OwnPtr<HRTFKernelList> kernelListR = adoptPtr(new HRTFKernelList(NumberOfTotalAzimuths));
237
238 // Load convolution kernels from HRTF files.
239 int interpolatedIndex = 0;
240 for (unsigned rawIndex = 0; rawIndex < NumberOfRawAzimuths; ++rawIndex) {
241 // Don't let elevation exceed maximum for this azimuth.
242 int maxElevation = maxElevations[rawIndex];
243 int actualElevation = std::min(elevation, maxElevation);
244
245 bool success = calculateKernelsForAzimuthElevation(rawIndex * AzimuthSpacing, actualElevation, sampleRate, subjectName, kernelListL->at(interpolatedIndex), kernelListR->at(interpolatedIndex));
246 if (!success)
247 return nullptr;
248
249 interpolatedIndex += InterpolationFactor;
250 }
251
252 // Now go back and interpolate intermediate azimuth values.
253 for (unsigned i = 0; i < NumberOfTotalAzimuths; i += InterpolationFactor) {
254 int j = (i + InterpolationFactor) % NumberOfTotalAzimuths;
255
256 // Create the interpolated convolution kernels and delays.
257 for (unsigned jj = 1; jj < InterpolationFactor; ++jj) {
258 float x = float(jj) / float(InterpolationFactor); // interpolate from 0 -> 1
259
260 (*kernelListL)[i + jj] = HRTFKernel::createInterpolatedKernel(kernelListL->at(i).get(), kernelListL->at(j).get(), x);
261 (*kernelListR)[i + jj] = HRTFKernel::createInterpolatedKernel(kernelListR->at(i).get(), kernelListR->at(j).get(), x);
262 }
263 }
264
265 OwnPtr<HRTFElevation> hrtfElevation = adoptPtr(new HRTFElevation(kernelListL.release(), kernelListR.release(), elevation, sampleRate));
266 return hrtfElevation.release();
267 }
268
createByInterpolatingSlices(HRTFElevation * hrtfElevation1,HRTFElevation * hrtfElevation2,float x,float sampleRate)269 PassOwnPtr<HRTFElevation> HRTFElevation::createByInterpolatingSlices(HRTFElevation* hrtfElevation1, HRTFElevation* hrtfElevation2, float x, float sampleRate)
270 {
271 ASSERT(hrtfElevation1 && hrtfElevation2);
272 if (!hrtfElevation1 || !hrtfElevation2)
273 return nullptr;
274
275 ASSERT(x >= 0.0 && x < 1.0);
276
277 OwnPtr<HRTFKernelList> kernelListL = adoptPtr(new HRTFKernelList(NumberOfTotalAzimuths));
278 OwnPtr<HRTFKernelList> kernelListR = adoptPtr(new HRTFKernelList(NumberOfTotalAzimuths));
279
280 HRTFKernelList* kernelListL1 = hrtfElevation1->kernelListL();
281 HRTFKernelList* kernelListR1 = hrtfElevation1->kernelListR();
282 HRTFKernelList* kernelListL2 = hrtfElevation2->kernelListL();
283 HRTFKernelList* kernelListR2 = hrtfElevation2->kernelListR();
284
285 // Interpolate kernels of corresponding azimuths of the two elevations.
286 for (unsigned i = 0; i < NumberOfTotalAzimuths; ++i) {
287 (*kernelListL)[i] = HRTFKernel::createInterpolatedKernel(kernelListL1->at(i).get(), kernelListL2->at(i).get(), x);
288 (*kernelListR)[i] = HRTFKernel::createInterpolatedKernel(kernelListR1->at(i).get(), kernelListR2->at(i).get(), x);
289 }
290
291 // Interpolate elevation angle.
292 double angle = (1.0 - x) * hrtfElevation1->elevationAngle() + x * hrtfElevation2->elevationAngle();
293
294 OwnPtr<HRTFElevation> hrtfElevation = adoptPtr(new HRTFElevation(kernelListL.release(), kernelListR.release(), static_cast<int>(angle), sampleRate));
295 return hrtfElevation.release();
296 }
297
getKernelsFromAzimuth(double azimuthBlend,unsigned azimuthIndex,HRTFKernel * & kernelL,HRTFKernel * & kernelR,double & frameDelayL,double & frameDelayR)298 void HRTFElevation::getKernelsFromAzimuth(double azimuthBlend, unsigned azimuthIndex, HRTFKernel* &kernelL, HRTFKernel* &kernelR, double& frameDelayL, double& frameDelayR)
299 {
300 bool checkAzimuthBlend = azimuthBlend >= 0.0 && azimuthBlend < 1.0;
301 ASSERT(checkAzimuthBlend);
302 if (!checkAzimuthBlend)
303 azimuthBlend = 0.0;
304
305 unsigned numKernels = m_kernelListL->size();
306
307 bool isIndexGood = azimuthIndex < numKernels;
308 ASSERT(isIndexGood);
309 if (!isIndexGood) {
310 kernelL = 0;
311 kernelR = 0;
312 return;
313 }
314
315 // Return the left and right kernels.
316 kernelL = m_kernelListL->at(azimuthIndex).get();
317 kernelR = m_kernelListR->at(azimuthIndex).get();
318
319 frameDelayL = m_kernelListL->at(azimuthIndex)->frameDelay();
320 frameDelayR = m_kernelListR->at(azimuthIndex)->frameDelay();
321
322 int azimuthIndex2 = (azimuthIndex + 1) % numKernels;
323 double frameDelay2L = m_kernelListL->at(azimuthIndex2)->frameDelay();
324 double frameDelay2R = m_kernelListR->at(azimuthIndex2)->frameDelay();
325
326 // Linearly interpolate delays.
327 frameDelayL = (1.0 - azimuthBlend) * frameDelayL + azimuthBlend * frameDelay2L;
328 frameDelayR = (1.0 - azimuthBlend) * frameDelayR + azimuthBlend * frameDelay2R;
329 }
330
331 } // namespace blink
332
333 #endif // ENABLE(WEB_AUDIO)
334