alc/panning.cpp

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 1999-2010 by authors.
   4  * This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  *  License along with this library; if not, write to the
  16  *  Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  * Or go to http://www.gnu.org/copyleft/lgpl.html
  19  */
  20
  21 #include "config.h"
  22
  23 #include <algorithm>
  24 #include <array>
  25 #include <chrono>
  26 #include <cmath>
  27 #include <cstdio>
  28 #include <cstring>
  29 #include <functional>
  30 #include <iterator>
  31 #include <memory>
  32 #include <new>
  33 #include <numeric>
  34 #include <string>
  35
  36 #include "AL/al.h"
  37 #include "AL/alc.h"
  38 #include "AL/alext.h"
  39
  40 #include "al/auxeffectslot.h"
  41 #include "alcmain.h"
  42 #include "alconfig.h"
  43 #include "almalloc.h"
  44 #include "alnumeric.h"
  45 #include "aloptional.h"
  46 #include "alspan.h"
  47 #include "alstring.h"
  48 #include "alu.h"
  49 #include "ambdec.h"
  50 #include "ambidefs.h"
  51 #include "bformatdec.h"
  52 #include "bs2b.h"
  53 #include "devformat.h"
  54 #include "hrtf.h"
  55 #include "logging.h"
  56 #include "math_defs.h"
  57 #include "opthelpers.h"
  58 #include "uhjfilter.h"
  59
  60
  61 constexpr std::array<float,MAX_AMBI_CHANNELS> AmbiScale::FromN3D;
  62 constexpr std::array<float,MAX_AMBI_CHANNELS> AmbiScale::FromSN3D;
  63 constexpr std::array<float,MAX_AMBI_CHANNELS> AmbiScale::FromFuMa;
  64 constexpr std::array<uint8_t,MAX_AMBI_CHANNELS> AmbiIndex::FromFuMa;
  65 constexpr std::array<uint8_t,MAX_AMBI_CHANNELS> AmbiIndex::FromACN;
  66 constexpr std::array<uint8_t,MAX_AMBI2D_CHANNELS> AmbiIndex::From2D;
  67 constexpr std::array<uint8_t,MAX_AMBI_CHANNELS> AmbiIndex::From3D;
  68
  69
  70 namespace {
  71
  72 using namespace std::placeholders;
  73 using std::chrono::seconds;
  74 using std::chrono::nanoseconds;
  75
  76 inline const char *GetLabelFromChannel(Channel channel)
  77 {
  78     switch(channel)
  79     {
  80         case FrontLeft: return "front-left";
  81         case FrontRight: return "front-right";
  82         case FrontCenter: return "front-center";
  83         case LFE: return "lfe";
  84         case BackLeft: return "back-left";
  85         case BackRight: return "back-right";
  86         case BackCenter: return "back-center";
  87         case SideLeft: return "side-left";
  88         case SideRight: return "side-right";
  89
  90         case UpperFrontLeft: return "upper-front-left";
  91         case UpperFrontRight: return "upper-front-right";
  92         case UpperBackLeft: return "upper-back-left";
  93         case UpperBackRight: return "upper-back-right";
  94         case LowerFrontLeft: return "lower-front-left";
  95         case LowerFrontRight: return "lower-front-right";
  96         case LowerBackLeft: return "lower-back-left";
  97         case LowerBackRight: return "lower-back-right";
  98
  99         case Aux0: return "aux-0";
 100         case Aux1: return "aux-1";
 101         case Aux2: return "aux-2";
 102         case Aux3: return "aux-3";
 103         case Aux4: return "aux-4";
 104         case Aux5: return "aux-5";
 105         case Aux6: return "aux-6";
 106         case Aux7: return "aux-7";
 107         case Aux8: return "aux-8";
 108         case Aux9: return "aux-9";
 109         case Aux10: return "aux-10";
 110         case Aux11: return "aux-11";
 111         case Aux12: return "aux-12";
 112         case Aux13: return "aux-13";
 113         case Aux14: return "aux-14";
 114         case Aux15: return "aux-15";
 115
 116         case MaxChannels: break;
 117     }
 118     return "(unknown)";
 119 }
 120
 121
 122 void AllocChannels(ALCdevice *device, const ALuint main_chans, const ALuint real_chans)
 123 {
 124     TRACE("Channel config, Main: %u, Real: %u\n", main_chans, real_chans);
 125
 126     /* Allocate extra channels for any post-filter output. */
 127     const ALuint num_chans{main_chans + real_chans};
 128
 129     TRACE("Allocating %u channels, %zu bytes\n", num_chans,
 130         num_chans*sizeof(device->MixBuffer[0]));
 131     device->MixBuffer.resize(num_chans);
 132     al::span<FloatBufferLine> buffer{device->MixBuffer.data(), device->MixBuffer.size()};
 133
 134     device->Dry.Buffer = buffer.first(main_chans);
 135     buffer = buffer.subspan(main_chans);
 136     if(real_chans != 0)
 137     {
 138         device->RealOut.Buffer = buffer.first(real_chans);
 139         buffer = buffer.subspan(real_chans);
 140     }
 141     else
 142         device->RealOut.Buffer = device->Dry.Buffer;
 143 }
 144
 145
 146 struct ChannelMap {
 147     Channel ChanName;
 148     ALfloat Config[MAX_AMBI2D_CHANNELS];
 149 };
 150
 151 bool MakeSpeakerMap(ALCdevice *device, const AmbDecConf *conf, ALuint (&speakermap)[MAX_OUTPUT_CHANNELS])
 152 {
 153     auto map_spkr = [device](const AmbDecConf::SpeakerConf &speaker) -> ALuint
 154     {
 155         /* NOTE: AmbDec does not define any standard speaker names, however
 156          * for this to work we have to by able to find the output channel
 157          * the speaker definition corresponds to. Therefore, OpenAL Soft
 158          * requires these channel labels to be recognized:
 159          *
 160          * LF = Front left
 161          * RF = Front right
 162          * LS = Side left
 163          * RS = Side right
 164          * LB = Back left
 165          * RB = Back right
 166          * CE = Front center
 167          * CB = Back center
 168          *
 169          * Additionally, surround51 will acknowledge back speakers for side
 170          * channels, and surround51rear will acknowledge side speakers for
 171          * back channels, to avoid issues with an ambdec expecting 5.1 to
 172          * use the side channels when the device is configured for back,
 173          * and vice-versa.
 174          */
 175         Channel ch{};
 176         if(speaker.Name == "LF")
 177             ch = FrontLeft;
 178         else if(speaker.Name == "RF")
 179             ch = FrontRight;
 180         else if(speaker.Name == "CE")
 181             ch = FrontCenter;
 182         else if(speaker.Name == "LS")
 183         {
 184             if(device->FmtChans == DevFmtX51Rear)
 185                 ch = BackLeft;
 186             else
 187                 ch = SideLeft;
 188         }
 189         else if(speaker.Name == "RS")
 190         {
 191             if(device->FmtChans == DevFmtX51Rear)
 192                 ch = BackRight;
 193             else
 194                 ch = SideRight;
 195         }
 196         else if(speaker.Name == "LB")
 197         {
 198             if(device->FmtChans == DevFmtX51)
 199                 ch = SideLeft;
 200             else
 201                 ch = BackLeft;
 202         }
 203         else if(speaker.Name == "RB")
 204         {
 205             if(device->FmtChans == DevFmtX51)
 206                 ch = SideRight;
 207             else
 208                 ch = BackRight;
 209         }
 210         else if(speaker.Name == "CB")
 211             ch = BackCenter;
 212         else
 213         {
 214             const char *name{speaker.Name.c_str()};
 215             unsigned int n;
 216             char c;
 217
 218             if(sscanf(name, "AUX%u%c", &n, &c) == 1 && n < 16)
 219                 ch = static_cast<Channel>(Aux0+n);
 220             else
 221             {
 222                 ERR("AmbDec speaker label \"%s\" not recognized\n", name);
 223                 return INVALID_CHANNEL_INDEX;
 224             }
 225         }
 226         const ALuint chidx{GetChannelIdxByName(device->RealOut, ch)};
 227         if(chidx == INVALID_CHANNEL_INDEX)
 228             ERR("Failed to lookup AmbDec speaker label %s\n", speaker.Name.c_str());
 229         return chidx;
 230     };
 231     std::transform(conf->Speakers.begin(), conf->Speakers.end(), std::begin(speakermap), map_spkr);
 232     /* Return success if no invalid entries are found. */
 233     auto spkrmap_end = std::begin(speakermap) + conf->Speakers.size();
 234     return std::find(std::begin(speakermap), spkrmap_end, INVALID_CHANNEL_INDEX) == spkrmap_end;
 235 }
 236
 237
 238 constexpr ChannelMap MonoCfg[1] = {
 239     { FrontCenter, { 1.0f } },
 240 }, StereoCfg[2] = {
 241     { FrontLeft,   { 5.00000000e-1f,  2.88675135e-1f,  5.52305643e-2f } },
 242     { FrontRight,  { 5.00000000e-1f, -2.88675135e-1f,  5.52305643e-2f } },
 243 }, QuadCfg[4] = {
 244     { BackLeft,    { 3.53553391e-1f,  2.04124145e-1f, -2.04124145e-1f } },
 245     { FrontLeft,   { 3.53553391e-1f,  2.04124145e-1f,  2.04124145e-1f } },
 246     { FrontRight,  { 3.53553391e-1f, -2.04124145e-1f,  2.04124145e-1f } },
 247     { BackRight,   { 3.53553391e-1f, -2.04124145e-1f, -2.04124145e-1f } },
 248 }, X51SideCfg[4] = {
 249     { SideLeft,    { 3.33000782e-1f,  1.89084803e-1f, -2.00042375e-1f, -2.12307769e-2f, -1.14579885e-2f } },
 250     { FrontLeft,   { 1.88542860e-1f,  1.27709292e-1f,  1.66295695e-1f,  7.30571517e-2f,  2.10901184e-2f } },
 251     { FrontRight,  { 1.88542860e-1f, -1.27709292e-1f,  1.66295695e-1f, -7.30571517e-2f,  2.10901184e-2f } },
 252     { SideRight,   { 3.33000782e-1f, -1.89084803e-1f, -2.00042375e-1f,  2.12307769e-2f, -1.14579885e-2f } },
 253 }, X51RearCfg[4] = {
 254     { BackLeft,    { 3.33000782e-1f,  1.89084803e-1f, -2.00042375e-1f, -2.12307769e-2f, -1.14579885e-2f } },
 255     { FrontLeft,   { 1.88542860e-1f,  1.27709292e-1f,  1.66295695e-1f,  7.30571517e-2f,  2.10901184e-2f } },
 256     { FrontRight,  { 1.88542860e-1f, -1.27709292e-1f,  1.66295695e-1f, -7.30571517e-2f,  2.10901184e-2f } },
 257     { BackRight,   { 3.33000782e-1f, -1.89084803e-1f, -2.00042375e-1f,  2.12307769e-2f, -1.14579885e-2f } },
 258 }, X61Cfg[6] = {
 259     { SideLeft,    { 2.04460341e-1f,  2.17177926e-1f, -4.39996780e-2f, -2.60790269e-2f, -6.87239792e-2f } },
 260     { FrontLeft,   { 1.58923161e-1f,  9.21772680e-2f,  1.59658796e-1f,  6.66278083e-2f,  3.84686854e-2f } },
 261     { FrontRight,  { 1.58923161e-1f, -9.21772680e-2f,  1.59658796e-1f, -6.66278083e-2f,  3.84686854e-2f } },
 262     { SideRight,   { 2.04460341e-1f, -2.17177926e-1f, -4.39996780e-2f,  2.60790269e-2f, -6.87239792e-2f } },
 263     { BackCenter,  { 2.50001688e-1f,  0.00000000e+0f, -2.50000094e-1f,  0.00000000e+0f,  6.05133395e-2f } },
 264 }, X71Cfg[6] = {
 265     { BackLeft,    { 2.04124145e-1f,  1.08880247e-1f, -1.88586120e-1f, -1.29099444e-1f,  7.45355993e-2f,  3.73460789e-2f,  0.00000000e+0f } },
 266     { SideLeft,    { 2.04124145e-1f,  2.17760495e-1f,  0.00000000e+0f,  0.00000000e+0f, -1.49071198e-1f, -3.73460789e-2f,  0.00000000e+0f } },
 267     { FrontLeft,   { 2.04124145e-1f,  1.08880247e-1f,  1.88586120e-1f,  1.29099444e-1f,  7.45355993e-2f,  3.73460789e-2f,  0.00000000e+0f } },
 268     { FrontRight,  { 2.04124145e-1f, -1.08880247e-1f,  1.88586120e-1f, -1.29099444e-1f,  7.45355993e-2f, -3.73460789e-2f,  0.00000000e+0f } },
 269     { SideRight,   { 2.04124145e-1f, -2.17760495e-1f,  0.00000000e+0f,  0.00000000e+0f, -1.49071198e-1f,  3.73460789e-2f,  0.00000000e+0f } },
 270     { BackRight,   { 2.04124145e-1f, -1.08880247e-1f, -1.88586120e-1f,  1.29099444e-1f,  7.45355993e-2f, -3.73460789e-2f,  0.00000000e+0f } },
 271 };
 272
 273 void InitNearFieldCtrl(ALCdevice *device, ALfloat ctrl_dist, ALuint order,
 274     const al::span<const ALuint,MAX_AMBI_ORDER+1> chans_per_order)
 275 {
 276     /* NFC is only used when AvgSpeakerDist is greater than 0. */
 277     const char *devname{device->DeviceName.c_str()};
 278     if(!GetConfigValueBool(devname, "decoder", "nfc", 0) || !(ctrl_dist > 0.0f))
 279         return;
 280
 281     device->AvgSpeakerDist = clampf(ctrl_dist, 0.1f, 10.0f);
 282     TRACE("Using near-field reference distance: %.2f meters\n", device->AvgSpeakerDist);
 283
 284     auto iter = std::copy(chans_per_order.begin(), chans_per_order.begin()+order+1,
 285         std::begin(device->NumChannelsPerOrder));
 286     std::fill(iter, std::end(device->NumChannelsPerOrder), 0u);
 287 }
 288
 289 void InitDistanceComp(ALCdevice *device, const AmbDecConf *conf,
 290     const ALuint (&speakermap)[MAX_OUTPUT_CHANNELS])
 291 {
 292     auto get_max = std::bind(maxf, _1,
 293         std::bind(std::mem_fn(&AmbDecConf::SpeakerConf::Distance), _2));
 294     const ALfloat maxdist{
 295         std::accumulate(conf->Speakers.begin(), conf->Speakers.end(), float{0.0f}, get_max)};
 296
 297     const char *devname{device->DeviceName.c_str()};
 298     if(!GetConfigValueBool(devname, "decoder", "distance-comp", 1) || !(maxdist > 0.0f))
 299         return;
 300
 301     const auto distSampleScale = static_cast<ALfloat>(device->Frequency)/SPEEDOFSOUNDMETRESPERSEC;
 302     const auto ChanDelay = device->ChannelDelay.as_span();
 303     size_t total{0u};
 304     for(size_t i{0u};i < conf->Speakers.size();i++)
 305     {
 306         const AmbDecConf::SpeakerConf &speaker = conf->Speakers[i];
 307         const ALuint chan{speakermap[i]};
 308
 309         /* Distance compensation only delays in steps of the sample rate. This
 310          * is a bit less accurate since the delay time falls to the nearest
 311          * sample time, but it's far simpler as it doesn't have to deal with
 312          * phase offsets. This means at 48khz, for instance, the distance delay
 313          * will be in steps of about 7 millimeters.
 314          */
 315         ALfloat delay{std::floor((maxdist - speaker.Distance)*distSampleScale + 0.5f)};
 316         if(delay > ALfloat{MAX_DELAY_LENGTH-1})
 317         {
 318             ERR("Delay for speaker \"%s\" exceeds buffer length (%f > %d)\n",
 319                 speaker.Name.c_str(), delay, MAX_DELAY_LENGTH-1);
 320             delay = ALfloat{MAX_DELAY_LENGTH-1};
 321         }
 322
 323         ChanDelay[chan].Length = static_cast<ALuint>(delay);
 324         ChanDelay[chan].Gain = speaker.Distance / maxdist;
 325         TRACE("Channel %u \"%s\" distance compensation: %u samples, %f gain\n", chan,
 326             speaker.Name.c_str(), ChanDelay[chan].Length, ChanDelay[chan].Gain);
 327
 328         /* Round up to the next 4th sample, so each channel buffer starts
 329          * 16-byte aligned.
 330          */
 331         total += RoundUp(ChanDelay[chan].Length, 4);
 332     }
 333
 334     if(total > 0)
 335     {
 336         device->ChannelDelay.setSampleCount(total);
 337         ChanDelay[0].Buffer = device->ChannelDelay.getSamples();
 338         auto set_bufptr = [](const DistanceComp::DistData &last, const DistanceComp::DistData &cur) -> DistanceComp::DistData
 339         {
 340             DistanceComp::DistData ret{cur};
 341             ret.Buffer = last.Buffer + RoundUp(last.Length, 4);
 342             return ret;
 343         };
 344         std::partial_sum(ChanDelay.begin(), ChanDelay.end(), ChanDelay.begin(), set_bufptr);
 345     }
 346 }
 347
 348
 349 auto GetAmbiScales(AmbiNorm scaletype) noexcept -> const std::array<float,MAX_AMBI_CHANNELS>&
 350 {
 351     if(scaletype == AmbiNorm::FuMa) return AmbiScale::FromFuMa;
 352     if(scaletype == AmbiNorm::SN3D) return AmbiScale::FromSN3D;
 353     return AmbiScale::FromN3D;
 354 }
 355
 356 auto GetAmbiLayout(AmbiLayout layouttype) noexcept -> const std::array<uint8_t,MAX_AMBI_CHANNELS>&
 357 {
 358     if(layouttype == AmbiLayout::FuMa) return AmbiIndex::FromFuMa;
 359     return AmbiIndex::FromACN;
 360 }
 361
 362
 363 void InitPanning(ALCdevice *device)
 364 {
 365     al::span<const ChannelMap> chanmap;
 366     ALuint coeffcount{};
 367
 368     switch(device->FmtChans)
 369     {
 370         case DevFmtMono:
 371             chanmap = MonoCfg;
 372             coeffcount = 1;
 373             break;
 374
 375         case DevFmtStereo:
 376             chanmap = StereoCfg;
 377             coeffcount = 3;
 378             break;
 379
 380         case DevFmtQuad:
 381             chanmap = QuadCfg;
 382             coeffcount = 3;
 383             break;
 384
 385         case DevFmtX51:
 386             chanmap = X51SideCfg;
 387             coeffcount = 5;
 388             break;
 389
 390         case DevFmtX51Rear:
 391             chanmap = X51RearCfg;
 392             coeffcount = 5;
 393             break;
 394
 395         case DevFmtX61:
 396             chanmap = X61Cfg;
 397             coeffcount = 5;
 398             break;
 399
 400         case DevFmtX71:
 401             chanmap = X71Cfg;
 402             coeffcount = 7;
 403             break;
 404
 405         case DevFmtAmbi3D:
 406             break;
 407     }
 408
 409     if(device->FmtChans == DevFmtAmbi3D)
 410     {
 411         const char *devname{device->DeviceName.c_str()};
 412         const std::array<uint8_t,MAX_AMBI_CHANNELS> &acnmap = GetAmbiLayout(device->mAmbiLayout);
 413         const std::array<float,MAX_AMBI_CHANNELS> &n3dscale = GetAmbiScales(device->mAmbiScale);
 414
 415         /* For DevFmtAmbi3D, the ambisonic order is already set. */
 416         const size_t count{AmbiChannelsFromOrder(device->mAmbiOrder)};
 417         std::transform(acnmap.begin(), acnmap.begin()+count, std::begin(device->Dry.AmbiMap),
 418             [&n3dscale](const uint8_t &acn) noexcept -> BFChannelConfig
 419             { return BFChannelConfig{1.0f/n3dscale[acn], acn}; }
 420         );
 421         AllocChannels(device, static_cast<ALuint>(count), 0);
 422
 423         ALfloat nfc_delay{ConfigValueFloat(devname, "decoder", "nfc-ref-delay").value_or(0.0f)};
 424         if(nfc_delay > 0.0f)
 425         {
 426             static const ALuint chans_per_order[MAX_AMBI_ORDER+1]{ 1, 3, 5, 7 };
 427             InitNearFieldCtrl(device, nfc_delay * SPEEDOFSOUNDMETRESPERSEC, device->mAmbiOrder,
 428                 chans_per_order);
 429         }
 430     }
 431     else
 432     {
 433         ChannelDec chancoeffs[MAX_OUTPUT_CHANNELS]{};
 434         ALuint idxmap[MAX_OUTPUT_CHANNELS]{};
 435         for(size_t i{0u};i < chanmap.size();++i)
 436         {
 437             const ALuint idx{GetChannelIdxByName(device->RealOut, chanmap[i].ChanName)};
 438             if(idx == INVALID_CHANNEL_INDEX)
 439             {
 440                 ERR("Failed to find %s channel in device\n",
 441                     GetLabelFromChannel(chanmap[i].ChanName));
 442                 continue;
 443             }
 444             idxmap[i] = idx;
 445             std::copy_n(chanmap[i].Config, coeffcount, chancoeffs[i]);
 446         }
 447
 448         /* For non-DevFmtAmbi3D, set the ambisonic order given the mixing
 449          * channel count. Built-in speaker decoders are always 2D, so just
 450          * reverse that calculation.
 451          */
 452         device->mAmbiOrder = (coeffcount-1) / 2;
 453
 454         std::transform(AmbiIndex::From2D.begin(), AmbiIndex::From2D.begin()+coeffcount,
 455             std::begin(device->Dry.AmbiMap),
 456             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
 457         );
 458         AllocChannels(device, coeffcount, device->channelsFromFmt());
 459
 460         TRACE("Enabling %s-order%s ambisonic decoder\n",
 461             (coeffcount > 5) ? "third" :
 462             (coeffcount > 3) ? "second" : "first",
 463             ""
 464         );
 465         device->AmbiDecoder = al::make_unique<BFormatDec>(coeffcount,
 466             static_cast<ALsizei>(chanmap.size()), chancoeffs, idxmap);
 467     }
 468 }
 469
 470 void InitCustomPanning(ALCdevice *device, bool hqdec, const AmbDecConf *conf,
 471     const ALuint (&speakermap)[MAX_OUTPUT_CHANNELS])
 472 {
 473     static const ALuint chans_per_order2d[MAX_AMBI_ORDER+1] = { 1, 2, 2, 2 };
 474     static const ALuint chans_per_order3d[MAX_AMBI_ORDER+1] = { 1, 3, 5, 7 };
 475
 476     if(!hqdec && conf->FreqBands != 1)
 477         ERR("Basic renderer uses the high-frequency matrix as single-band (xover_freq = %.0fhz)\n",
 478             conf->XOverFreq);
 479
 480     const ALuint order{(conf->ChanMask > AMBI_2ORDER_MASK) ? 3u :
 481         (conf->ChanMask > AMBI_1ORDER_MASK) ? 2u : 1u};
 482     device->mAmbiOrder = order;
 483
 484     ALuint count;
 485     if((conf->ChanMask&AMBI_PERIPHONIC_MASK))
 486     {
 487         count = static_cast<ALuint>(AmbiChannelsFromOrder(order));
 488         std::transform(AmbiIndex::From3D.begin(), AmbiIndex::From3D.begin()+count,
 489             std::begin(device->Dry.AmbiMap),
 490             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
 491         );
 492     }
 493     else
 494     {
 495         count = static_cast<ALuint>(Ambi2DChannelsFromOrder(order));
 496         std::transform(AmbiIndex::From2D.begin(), AmbiIndex::From2D.begin()+count,
 497             std::begin(device->Dry.AmbiMap),
 498             [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
 499         );
 500     }
 501     AllocChannels(device, count, device->channelsFromFmt());
 502
 503     TRACE("Enabling %s-band %s-order%s ambisonic decoder\n",
 504         (!hqdec || conf->FreqBands == 1) ? "single" : "dual",
 505         (conf->ChanMask > AMBI_2ORDER_MASK) ? "third" :
 506         (conf->ChanMask > AMBI_1ORDER_MASK) ? "second" : "first",
 507         (conf->ChanMask&AMBI_PERIPHONIC_MASK) ? " periphonic" : ""
 508     );
 509     device->AmbiDecoder = al::make_unique<BFormatDec>(conf, hqdec, count, device->Frequency,
 510         speakermap);
 511
 512     auto accum_spkr_dist = std::bind(std::plus<float>{}, _1,
 513         std::bind(std::mem_fn(&AmbDecConf::SpeakerConf::Distance), _2));
 514     const ALfloat avg_dist{
 515         std::accumulate(conf->Speakers.begin(), conf->Speakers.end(), 0.0f, accum_spkr_dist) /
 516         static_cast<ALfloat>(conf->Speakers.size())};
 517     InitNearFieldCtrl(device, avg_dist, order,
 518         (conf->ChanMask&AMBI_PERIPHONIC_MASK) ? chans_per_order3d : chans_per_order2d);
 519
 520     InitDistanceComp(device, conf, speakermap);
 521 }
 522
 523 void InitHrtfPanning(ALCdevice *device)
 524 {
 525     static const AngularPoint AmbiPoints[]{
 526         { Deg2Rad(  0.000000f), Deg2Rad(   0.000000f) },
 527         { Deg2Rad(  0.000000f), Deg2Rad( 180.000000f) },
 528         { Deg2Rad(  0.000000f), Deg2Rad( -90.000000f) },
 529         { Deg2Rad(  0.000000f), Deg2Rad(  90.000000f) },
 530         { Deg2Rad( 90.000000f), Deg2Rad(   0.000000f) },
 531         { Deg2Rad(-90.000000f), Deg2Rad(   0.000000f) },
 532         { Deg2Rad( 45.000000f), Deg2Rad( -90.000000f) },
 533         { Deg2Rad(-45.000000f), Deg2Rad( -90.000000f) },
 534         { Deg2Rad( 45.000000f), Deg2Rad(  90.000000f) },
 535         { Deg2Rad(-45.000000f), Deg2Rad(  90.000000f) },
 536         { Deg2Rad( 45.000000f), Deg2Rad(   0.000000f) },
 537         { Deg2Rad(-45.000000f), Deg2Rad(   0.000000f) },
 538         { Deg2Rad( 45.000000f), Deg2Rad( 180.000000f) },
 539         { Deg2Rad(-45.000000f), Deg2Rad( 180.000000f) },
 540         { Deg2Rad(  0.000000f), Deg2Rad( -45.000000f) },
 541         { Deg2Rad(  0.000000f), Deg2Rad(  45.000000f) },
 542         { Deg2Rad(  0.000000f), Deg2Rad(-135.000000f) },
 543         { Deg2Rad(  0.000000f), Deg2Rad( 135.000000f) },
 544         { Deg2Rad( 35.264390f), Deg2Rad( -45.000000f) },
 545         { Deg2Rad(-35.264390f), Deg2Rad( -45.000000f) },
 546         { Deg2Rad( 35.264390f), Deg2Rad(  45.000000f) },
 547         { Deg2Rad(-35.264390f), Deg2Rad(  45.000000f) },
 548         { Deg2Rad( 35.264390f), Deg2Rad(-135.000000f) },
 549         { Deg2Rad(-35.264390f), Deg2Rad(-135.000000f) },
 550         { Deg2Rad( 35.264390f), Deg2Rad( 135.000000f) },
 551         { Deg2Rad(-35.264390f), Deg2Rad( 135.000000f) },
 552     };
 553     static const float AmbiMatrix[][MAX_AMBI_CHANNELS]{
 554         { 3.84615387e-02f,  0.00000000e+00f,  0.00000000e+00f,  6.66173389e-02f,  0.00000000e+00f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  8.60662966e-02f },
 555         { 3.84615387e-02f,  0.00000000e+00f,  0.00000000e+00f, -6.66173389e-02f,  0.00000000e+00f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  8.60662966e-02f },
 556         { 3.84615387e-02f,  6.66173389e-02f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f, -8.60662966e-02f },
 557         { 3.84615387e-02f, -6.66173389e-02f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f, -8.60662966e-02f },
 558         { 3.84615379e-02f,  0.00000000e+00f,  6.66173384e-02f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f,  9.93807988e-02f,  0.00000000e+00f,  0.00000000e+00f },
 559         { 3.84615379e-02f,  0.00000000e+00f, -6.66173384e-02f,  0.00000000e+00f,  0.00000000e+00f,  0.00000000e+00f,  9.93807988e-02f,  0.00000000e+00f,  0.00000000e+00f },
 560         { 3.84615383e-02f,  4.71055721e-02f,  4.71055717e-02f,  0.00000000e+00f,  0.00000000e+00f,  6.83467647e-02f,  2.48451995e-02f,  0.00000000e+00f, -4.30331483e-02f },
 561         { 3.84615383e-02f,  4.71055721e-02f, -4.71055717e-02f,  0.00000000e+00f,  0.00000000e+00f, -6.83467647e-02f,  2.48451995e-02f,  0.00000000e+00f, -4.30331483e-02f },
 562         { 3.84615383e-02f, -4.71055721e-02f,  4.71055717e-02f,  0.00000000e+00f,  0.00000000e+00f, -6.83467647e-02f,  2.48451995e-02f,  0.00000000e+00f, -4.30331483e-02f },
 563         { 3.84615383e-02f, -4.71055721e-02f, -4.71055717e-02f,  0.00000000e+00f,  0.00000000e+00f,  6.83467647e-02f,  2.48451995e-02f,  0.00000000e+00f, -4.30331483e-02f },
 564         { 3.84615383e-02f,  0.00000000e+00f,  4.71055717e-02f,  4.71055721e-02f,  0.00000000e+00f,  0.00000000e+00f,  2.48451995e-02f,  6.83467647e-02f,  4.30331483e-02f },
 565         { 3.84615383e-02f,  0.00000000e+00f, -4.71055717e-02f,  4.71055721e-02f,  0.00000000e+00f,  0.00000000e+00f,  2.48451995e-02f, -6.83467647e-02f,  4.30331483e-02f },
 566         { 3.84615383e-02f,  0.00000000e+00f,  4.71055717e-02f, -4.71055721e-02f,  0.00000000e+00f,  0.00000000e+00f,  2.48451995e-02f, -6.83467647e-02f,  4.30331483e-02f },
 567         { 3.84615383e-02f,  0.00000000e+00f, -4.71055717e-02f, -4.71055721e-02f,  0.00000000e+00f,  0.00000000e+00f,  2.48451995e-02f,  6.83467647e-02f,  4.30331483e-02f },
 568         { 3.84615387e-02f,  4.71055721e-02f,  0.00000000e+00f,  4.71055721e-02f,  6.83467654e-02f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  0.00000000e+00f },
 569         { 3.84615387e-02f, -4.71055721e-02f,  0.00000000e+00f,  4.71055721e-02f, -6.83467654e-02f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  0.00000000e+00f },
 570         { 3.84615387e-02f,  4.71055721e-02f,  0.00000000e+00f, -4.71055721e-02f, -6.83467654e-02f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  0.00000000e+00f },
 571         { 3.84615387e-02f, -4.71055721e-02f,  0.00000000e+00f, -4.71055721e-02f,  6.83467654e-02f,  0.00000000e+00f, -4.96903997e-02f,  0.00000000e+00f,  0.00000000e+00f },
 572         { 3.84615385e-02f,  3.84615384e-02f,  3.84615386e-02f,  3.84615384e-02f,  4.55645099e-02f,  4.55645100e-02f,  0.00000000e+00f,  4.55645100e-02f,  0.00000000e+00f },
 573         { 3.84615385e-02f,  3.84615384e-02f, -3.84615386e-02f,  3.84615384e-02f,  4.55645099e-02f, -4.55645100e-02f,  0.00000000e+00f, -4.55645100e-02f,  0.00000000e+00f },
 574         { 3.84615385e-02f, -3.84615384e-02f,  3.84615386e-02f,  3.84615384e-02f, -4.55645099e-02f, -4.55645100e-02f,  0.00000000e+00f,  4.55645100e-02f,  0.00000000e+00f },
 575         { 3.84615385e-02f, -3.84615384e-02f, -3.84615386e-02f,  3.84615384e-02f, -4.55645099e-02f,  4.55645100e-02f,  0.00000000e+00f, -4.55645100e-02f,  0.00000000e+00f },
 576         { 3.84615385e-02f,  3.84615384e-02f,  3.84615386e-02f, -3.84615384e-02f, -4.55645099e-02f,  4.55645100e-02f,  0.00000000e+00f, -4.55645100e-02f,  0.00000000e+00f },
 577         { 3.84615385e-02f,  3.84615384e-02f, -3.84615386e-02f, -3.84615384e-02f, -4.55645099e-02f, -4.55645100e-02f,  0.00000000e+00f,  4.55645100e-02f,  0.00000000e+00f },
 578         { 3.84615385e-02f, -3.84615384e-02f,  3.84615386e-02f, -3.84615384e-02f,  4.55645099e-02f, -4.55645100e-02f,  0.00000000e+00f, -4.55645100e-02f,  0.00000000e+00f },
 579         { 3.84615385e-02f, -3.84615384e-02f, -3.84615386e-02f, -3.84615384e-02f,  4.55645099e-02f,  4.55645100e-02f,  0.00000000e+00f,  4.55645100e-02f,  0.00000000e+00f },
 580     };
 581     static const float AmbiOrderHFGain1O[MAX_AMBI_ORDER+1]{
 582         3.60555128e+00f, 2.08166600e+00f
 583     }, AmbiOrderHFGain2O[MAX_AMBI_ORDER+1]{
 584         2.68741925e+00f, 2.08166600e+00f, 1.07496770e+00f
 585     };
 586     static const ALuint ChansPerOrder[MAX_AMBI_ORDER+1]{ 1, 3, 5, 7 };
 587     const float *AmbiOrderHFGain{AmbiOrderHFGain1O};
 588
 589     static_assert(al::size(AmbiPoints) == al::size(AmbiMatrix), "Ambisonic HRTF mismatch");
 590
 591     /* Don't bother with HOA when using full HRTF rendering. Nothing needs it,
 592      * and it eases the CPU/memory load.
 593      */
 594     device->mRenderMode = HrtfRender;
 595     ALuint ambi_order{1};
 596     if(auto modeopt = ConfigValueStr(device->DeviceName.c_str(), nullptr, "hrtf-mode"))
 597     {
 598         struct HrtfModeEntry {
 599             char name[8];
 600             RenderMode mode;
 601             ALuint order;
 602         };
 603         static const HrtfModeEntry hrtf_modes[]{
 604             { "full", HrtfRender, 1 },
 605             { "ambi1", NormalRender, 1 },
 606             { "ambi2", NormalRender, 2 },
 607         };
 608
 609         const char *mode{modeopt->c_str()};
 610         if(al::strcasecmp(mode, "basic") == 0 || al::strcasecmp(mode, "ambi3") == 0)
 611         {
 612             ERR("HRTF mode \"%s\" deprecated, substituting \"%s\"\n", mode, "ambi2");
 613             mode = "ambi2";
 614         }
 615
 616         auto match_entry = [mode](const HrtfModeEntry &entry) -> bool
 617         { return al::strcasecmp(mode, entry.name) == 0; };
 618         auto iter = std::find_if(std::begin(hrtf_modes), std::end(hrtf_modes), match_entry);
 619         if(iter == std::end(hrtf_modes))
 620             ERR("Unexpected hrtf-mode: %s\n", mode);
 621         else
 622         {
 623             device->mRenderMode = iter->mode;
 624             ambi_order = iter->order;
 625         }
 626     }
 627     TRACE("%u%s order %sHRTF rendering enabled, using \"%s\"\n", ambi_order,
 628         (((ambi_order%100)/10) == 1) ? "th" :
 629         ((ambi_order%10) == 1) ? "st" :
 630         ((ambi_order%10) == 2) ? "nd" :
 631         ((ambi_order%10) == 3) ? "rd" : "th",
 632         (device->mRenderMode == HrtfRender) ? "+ Full " : "",
 633         device->HrtfName.c_str());
 634
 635     if(ambi_order >= 2)
 636         AmbiOrderHFGain = AmbiOrderHFGain2O;
 637     else if(ambi_order == 1)
 638         AmbiOrderHFGain = AmbiOrderHFGain1O;
 639     device->mAmbiOrder = ambi_order;
 640
 641     const size_t count{AmbiChannelsFromOrder(ambi_order)};
 642     device->mHrtfState = DirectHrtfState::Create(count);
 643
 644     std::transform(AmbiIndex::From3D.begin(), AmbiIndex::From3D.begin()+count,
 645         std::begin(device->Dry.AmbiMap),
 646         [](const uint8_t &index) noexcept { return BFChannelConfig{1.0f, index}; }
 647     );
 648     AllocChannels(device, static_cast<ALuint>(count), device->channelsFromFmt());
 649
 650     BuildBFormatHrtf(device->mHrtf, device->mHrtfState.get(), AmbiPoints, AmbiMatrix,
 651         AmbiOrderHFGain);
 652
 653     HrtfEntry *Hrtf{device->mHrtf};
 654     InitNearFieldCtrl(device, Hrtf->field[0].distance, ambi_order, ChansPerOrder);
 655 }
 656
 657 void InitUhjPanning(ALCdevice *device)
 658 {
 659     /* UHJ is always 2D first-order. */
 660     constexpr size_t count{Ambi2DChannelsFromOrder(1)};
 661
 662     device->mAmbiOrder = 1;
 663
 664     auto acnmap_end = AmbiIndex::FromFuMa.begin() + count;
 665     std::transform(AmbiIndex::FromFuMa.begin(), acnmap_end, std::begin(device->Dry.AmbiMap),
 666         [](const uint8_t &acn) noexcept -> BFChannelConfig
 667         { return BFChannelConfig{1.0f/AmbiScale::FromFuMa[acn], acn}; }
 668     );
 669     AllocChannels(device, ALuint{count}, device->channelsFromFmt());
 670 }
 671
 672 } // namespace
 673
 674 void aluInitRenderer(ALCdevice *device, ALint hrtf_id, HrtfRequestMode hrtf_appreq, HrtfRequestMode hrtf_userreq)
 675 {
 676     /* Hold the HRTF the device last used, in case it's used again. */
 677     HrtfEntry *old_hrtf{device->mHrtf};
 678
 679     device->mHrtfState = nullptr;
 680     device->mHrtf = nullptr;
 681     device->HrtfName.clear();
 682     device->mRenderMode = NormalRender;
 683
 684     if(device->FmtChans != DevFmtStereo)
 685     {
 686         if(old_hrtf)
 687             old_hrtf->DecRef();
 688         old_hrtf = nullptr;
 689         if(hrtf_appreq == Hrtf_Enable)
 690             device->HrtfStatus = ALC_HRTF_UNSUPPORTED_FORMAT_SOFT;
 691
 692         const char *layout{nullptr};
 693         switch(device->FmtChans)
 694         {
 695             case DevFmtQuad: layout = "quad"; break;
 696             case DevFmtX51: /* fall-through */
 697             case DevFmtX51Rear: layout = "surround51"; break;
 698             case DevFmtX61: layout = "surround61"; break;
 699             case DevFmtX71: layout = "surround71"; break;
 700             /* Mono, Stereo, and Ambisonics output don't use custom decoders. */
 701             case DevFmtMono:
 702             case DevFmtStereo:
 703             case DevFmtAmbi3D:
 704                 break;
 705         }
 706
 707         const char *devname{device->DeviceName.c_str()};
 708         ALuint speakermap[MAX_OUTPUT_CHANNELS];
 709         AmbDecConf *pconf{nullptr};
 710         AmbDecConf conf{};
 711         if(layout)
 712         {
 713             if(auto decopt = ConfigValueStr(devname, "decoder", layout))
 714             {
 715                 if(!conf.load(decopt->c_str()))
 716                     ERR("Failed to load layout file %s\n", decopt->c_str());
 717                 else if(conf.Speakers.size() > MAX_OUTPUT_CHANNELS)
 718                     ERR("Unsupported speaker count %zu (max %d)\n", conf.Speakers.size(),
 719                         MAX_OUTPUT_CHANNELS);
 720                 else if(conf.ChanMask > AMBI_3ORDER_MASK)
 721                     ERR("Unsupported channel mask 0x%04x (max 0x%x)\n", conf.ChanMask,
 722                         AMBI_3ORDER_MASK);
 723                 else if(MakeSpeakerMap(device, &conf, speakermap))
 724                     pconf = &conf;
 725             }
 726         }
 727
 728         if(!pconf)
 729             InitPanning(device);
 730         else
 731         {
 732             int hqdec{GetConfigValueBool(devname, "decoder", "hq-mode", 1)};
 733             InitCustomPanning(device, !!hqdec, pconf, speakermap);
 734         }
 735         if(device->AmbiDecoder)
 736             device->PostProcess = &ALCdevice::ProcessAmbiDec;
 737         return;
 738     }
 739
 740     bool headphones{device->IsHeadphones != AL_FALSE};
 741     if(device->Type != Loopback)
 742     {
 743         if(auto modeopt = ConfigValueStr(device->DeviceName.c_str(), nullptr, "stereo-mode"))
 744         {
 745             const char *mode{modeopt->c_str()};
 746             if(al::strcasecmp(mode, "headphones") == 0)
 747                 headphones = true;
 748             else if(al::strcasecmp(mode, "speakers") == 0)
 749                 headphones = false;
 750             else if(al::strcasecmp(mode, "auto") != 0)
 751                 ERR("Unexpected stereo-mode: %s\n", mode);
 752         }
 753     }
 754
 755     if(hrtf_userreq == Hrtf_Default)
 756     {
 757         bool usehrtf = (headphones && hrtf_appreq != Hrtf_Disable) ||
 758                        (hrtf_appreq == Hrtf_Enable);
 759         if(!usehrtf) goto no_hrtf;
 760
 761         device->HrtfStatus = ALC_HRTF_ENABLED_SOFT;
 762         if(headphones && hrtf_appreq != Hrtf_Disable)
 763             device->HrtfStatus = ALC_HRTF_HEADPHONES_DETECTED_SOFT;
 764     }
 765     else
 766     {
 767         if(hrtf_userreq != Hrtf_Enable)
 768         {
 769             if(hrtf_appreq == Hrtf_Enable)
 770                 device->HrtfStatus = ALC_HRTF_DENIED_SOFT;
 771             goto no_hrtf;
 772         }
 773         device->HrtfStatus = ALC_HRTF_REQUIRED_SOFT;
 774     }
 775
 776     if(device->HrtfList.empty())
 777         device->HrtfList = EnumerateHrtf(device->DeviceName.c_str());
 778
 779     if(hrtf_id >= 0 && static_cast<ALuint>(hrtf_id) < device->HrtfList.size())
 780     {
 781         const EnumeratedHrtf &entry = device->HrtfList[static_cast<ALuint>(hrtf_id)];
 782         HrtfEntry *hrtf{GetLoadedHrtf(entry.hrtf)};
 783         if(hrtf && hrtf->sampleRate == device->Frequency)
 784         {
 785             device->mHrtf = hrtf;
 786             device->HrtfName = entry.name;
 787         }
 788         else if(hrtf)
 789             hrtf->DecRef();
 790     }
 791
 792     if(!device->mHrtf)
 793     {
 794         auto find_hrtf = [device](const EnumeratedHrtf &entry) -> bool
 795         {
 796             HrtfEntry *hrtf{GetLoadedHrtf(entry.hrtf)};
 797             if(!hrtf) return false;
 798             if(hrtf->sampleRate != device->Frequency)
 799             {
 800                 hrtf->DecRef();
 801                 return false;
 802             }
 803             device->mHrtf = hrtf;
 804             device->HrtfName = entry.name;
 805             return true;
 806         };
 807         std::find_if(device->HrtfList.cbegin(), device->HrtfList.cend(), find_hrtf);
 808     }
 809
 810     if(device->mHrtf)
 811     {
 812         if(old_hrtf)
 813             old_hrtf->DecRef();
 814         old_hrtf = nullptr;
 815
 816         InitHrtfPanning(device);
 817         device->PostProcess = &ALCdevice::ProcessHrtf;
 818         return;
 819     }
 820     device->HrtfStatus = ALC_HRTF_UNSUPPORTED_FORMAT_SOFT;
 821
 822 no_hrtf:
 823     if(old_hrtf)
 824         old_hrtf->DecRef();
 825     old_hrtf = nullptr;
 826
 827     device->mRenderMode = StereoPair;
 828
 829     if(device->Type != Loopback)
 830     {
 831         if(auto cflevopt = ConfigValueInt(device->DeviceName.c_str(), nullptr, "cf_level"))
 832         {
 833             if(*cflevopt > 0 && *cflevopt <= 6)
 834             {
 835                 device->Bs2b = al::make_unique<bs2b>();
 836                 bs2b_set_params(device->Bs2b.get(), *cflevopt,
 837                     static_cast<int>(device->Frequency));
 838                 TRACE("BS2B enabled\n");
 839                 InitPanning(device);
 840                 device->PostProcess = &ALCdevice::ProcessBs2b;
 841                 return;
 842             }
 843         }
 844     }
 845
 846     if(auto encopt = ConfigValueStr(device->DeviceName.c_str(), nullptr, "stereo-encoding"))
 847     {
 848         const char *mode{encopt->c_str()};
 849         if(al::strcasecmp(mode, "uhj") == 0)
 850             device->mRenderMode = NormalRender;
 851         else if(al::strcasecmp(mode, "panpot") != 0)
 852             ERR("Unexpected stereo-encoding: %s\n", mode);
 853     }
 854     if(device->mRenderMode == NormalRender)
 855     {
 856         device->Uhj_Encoder = al::make_unique<Uhj2Encoder>();
 857         TRACE("UHJ enabled\n");
 858         InitUhjPanning(device);
 859         device->PostProcess = &ALCdevice::ProcessUhj;
 860         return;
 861     }
 862
 863     TRACE("Stereo rendering\n");
 864     InitPanning(device);
 865     device->PostProcess = &ALCdevice::ProcessAmbiDec;
 866 }
 867
 868
 869 void aluInitEffectPanning(ALeffectslot *slot, ALCdevice *device)
 870 {
 871     const size_t count{AmbiChannelsFromOrder(device->mAmbiOrder)};
 872     slot->MixBuffer.resize(count);
 873     slot->MixBuffer.shrink_to_fit();
 874
 875     auto acnmap_end = AmbiIndex::From3D.begin() + count;
 876     auto iter = std::transform(AmbiIndex::From3D.begin(), acnmap_end, slot->Wet.AmbiMap.begin(),
 877         [](const uint8_t &acn) noexcept -> BFChannelConfig
 878         { return BFChannelConfig{1.0f, acn}; }
 879     );
 880     std::fill(iter, slot->Wet.AmbiMap.end(), BFChannelConfig{});
 881     slot->Wet.Buffer = {slot->MixBuffer.data(), slot->MixBuffer.size()};
 882 }
 883
 884
 885 void CalcAmbiCoeffs(const float y, const float z, const float x, const float spread,
 886     const al::span<float,MAX_AMBI_CHANNELS> coeffs)
 887 {
 888     /* Zeroth-order */
 889     coeffs[0]  = 1.0f; /* ACN 0 = 1 */
 890     /* First-order */
 891     coeffs[1]  = 1.732050808f * y; /* ACN 1 = sqrt(3) * Y */
 892     coeffs[2]  = 1.732050808f * z; /* ACN 2 = sqrt(3) * Z */
 893     coeffs[3]  = 1.732050808f * x; /* ACN 3 = sqrt(3) * X */
 894     /* Second-order */
 895     coeffs[4]  = 3.872983346f * x * y;             /* ACN 4 = sqrt(15) * X * Y */
 896     coeffs[5]  = 3.872983346f * y * z;             /* ACN 5 = sqrt(15) * Y * Z */
 897     coeffs[6]  = 1.118033989f * (z*z*3.0f - 1.0f); /* ACN 6 = sqrt(5)/2 * (3*Z*Z - 1) */
 898     coeffs[7]  = 3.872983346f * x * z;             /* ACN 7 = sqrt(15) * X * Z */
 899     coeffs[8]  = 1.936491673f * (x*x - y*y);       /* ACN 8 = sqrt(15)/2 * (X*X - Y*Y) */
 900     /* Third-order */
 901     coeffs[9]  =  2.091650066f * y * (x*x*3.0f - y*y);  /* ACN  9 = sqrt(35/8) * Y * (3*X*X - Y*Y) */
 902     coeffs[10] = 10.246950766f * z * x * y;             /* ACN 10 = sqrt(105) * Z * X * Y */
 903     coeffs[11] =  1.620185175f * y * (z*z*5.0f - 1.0f); /* ACN 11 = sqrt(21/8) * Y * (5*Z*Z - 1) */
 904     coeffs[12] =  1.322875656f * z * (z*z*5.0f - 3.0f); /* ACN 12 = sqrt(7)/2 * Z * (5*Z*Z - 3) */
 905     coeffs[13] =  1.620185175f * x * (z*z*5.0f - 1.0f); /* ACN 13 = sqrt(21/8) * X * (5*Z*Z - 1) */
 906     coeffs[14] =  5.123475383f * z * (x*x - y*y);       /* ACN 14 = sqrt(105)/2 * Z * (X*X - Y*Y) */
 907     coeffs[15] =  2.091650066f * x * (x*x - y*y*3.0f);  /* ACN 15 = sqrt(35/8) * X * (X*X - 3*Y*Y) */
 908     /* Fourth-order */
 909     /* ACN 16 = sqrt(35)*3/2 * X * Y * (X*X - Y*Y) */
 910     /* ACN 17 = sqrt(35/2)*3/2 * (3*X*X - Y*Y) * Y * Z */
 911     /* ACN 18 = sqrt(5)*3/2 * X * Y * (7*Z*Z - 1) */
 912     /* ACN 19 = sqrt(5/2)*3/2 * Y * Z * (7*Z*Z - 3)  */
 913     /* ACN 20 = 3/8 * (35*Z*Z*Z*Z - 30*Z*Z + 3) */
 914     /* ACN 21 = sqrt(5/2)*3/2 * X * Z * (7*Z*Z - 3) */
 915     /* ACN 22 = sqrt(5)*3/4 * (X*X - Y*Y) * (7*Z*Z - 1) */
 916     /* ACN 23 = sqrt(35/2)*3/2 * (X*X - 3*Y*Y) * X * Z */
 917     /* ACN 24 = sqrt(35)*3/8 * (X*X*X*X - 6*X*X*Y*Y + Y*Y*Y*Y) */
 918
 919     if(spread > 0.0f)
 920     {
 921         /* Implement the spread by using a spherical source that subtends the
 922          * angle spread. See:
 923          * http://www.ppsloan.org/publications/StupidSH36.pdf - Appendix A3
 924          *
 925          * When adjusted for N3D normalization instead of SN3D, these
 926          * calculations are:
 927          *
 928          * ZH0 = -sqrt(pi) * (-1+ca);
 929          * ZH1 =  0.5*sqrt(pi) * sa*sa;
 930          * ZH2 = -0.5*sqrt(pi) * ca*(-1+ca)*(ca+1);
 931          * ZH3 = -0.125*sqrt(pi) * (-1+ca)*(ca+1)*(5*ca*ca - 1);
 932          * ZH4 = -0.125*sqrt(pi) * ca*(-1+ca)*(ca+1)*(7*ca*ca - 3);
 933          * ZH5 = -0.0625*sqrt(pi) * (-1+ca)*(ca+1)*(21*ca*ca*ca*ca - 14*ca*ca + 1);
 934          *
 935          * The gain of the source is compensated for size, so that the
 936          * loudness doesn't depend on the spread. Thus:
 937          *
 938          * ZH0 = 1.0f;
 939          * ZH1 = 0.5f * (ca+1.0f);
 940          * ZH2 = 0.5f * (ca+1.0f)*ca;
 941          * ZH3 = 0.125f * (ca+1.0f)*(5.0f*ca*ca - 1.0f);
 942          * ZH4 = 0.125f * (ca+1.0f)*(7.0f*ca*ca - 3.0f)*ca;
 943          * ZH5 = 0.0625f * (ca+1.0f)*(21.0f*ca*ca*ca*ca - 14.0f*ca*ca + 1.0f);
 944          */
 945         const float ca{std::cos(spread * 0.5f)};
 946         /* Increase the source volume by up to +3dB for a full spread. */
 947         const float scale{std::sqrt(1.0f + spread/al::MathDefs<float>::Tau())};
 948
 949         const float ZH0_norm{scale};
 950         const float ZH1_norm{scale * 0.5f * (ca+1.f)};
 951         const float ZH2_norm{scale * 0.5f * (ca+1.f)*ca};
 952         const float ZH3_norm{scale * 0.125f * (ca+1.f)*(5.f*ca*ca-1.f)};
 953
 954         /* Zeroth-order */
 955         coeffs[0]  *= ZH0_norm;
 956         /* First-order */
 957         coeffs[1]  *= ZH1_norm;
 958         coeffs[2]  *= ZH1_norm;
 959         coeffs[3]  *= ZH1_norm;
 960         /* Second-order */
 961         coeffs[4]  *= ZH2_norm;
 962         coeffs[5]  *= ZH2_norm;
 963         coeffs[6]  *= ZH2_norm;
 964         coeffs[7]  *= ZH2_norm;
 965         coeffs[8]  *= ZH2_norm;
 966         /* Third-order */
 967         coeffs[9]  *= ZH3_norm;
 968         coeffs[10] *= ZH3_norm;
 969         coeffs[11] *= ZH3_norm;
 970         coeffs[12] *= ZH3_norm;
 971         coeffs[13] *= ZH3_norm;
 972         coeffs[14] *= ZH3_norm;
 973         coeffs[15] *= ZH3_norm;
 974     }
 975 }
 976
 977 void ComputePanGains(const MixParams *mix, const float*RESTRICT coeffs, const float ingain,
 978     const al::span<float,MAX_OUTPUT_CHANNELS> gains)
 979 {
 980     auto ambimap = mix->AmbiMap.cbegin();
 981
 982     auto iter = std::transform(ambimap, ambimap+mix->Buffer.size(), gains.begin(),
 983         [coeffs,ingain](const BFChannelConfig &chanmap) noexcept -> float
 984         { return chanmap.Scale * coeffs[chanmap.Index] * ingain; }
 985     );
 986     std::fill(iter, gains.end(), 0.0f);
 987 }