alc/backends/sdl2.cpp

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2018 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 "backends/sdl2.h"
  24
  25 #include <cassert>
  26 #include <cstdlib>
  27 #include <cstring>
  28 #include <string>
  29
  30 #include "AL/al.h"
  31
  32 #include "alcmain.h"
  33 #include "alexcpt.h"
  34 #include "almalloc.h"
  35 #include "alu.h"
  36 #include "logging.h"
  37
  38 #include <SDL2/SDL.h>
  39
  40
  41 namespace {
  42
  43 #ifdef _WIN32
  44 #define DEVNAME_PREFIX "OpenAL Soft on "
  45 #else
  46 #define DEVNAME_PREFIX ""
  47 #endif
  48
  49 constexpr ALCchar defaultDeviceName[] = DEVNAME_PREFIX "Default Device";
  50
  51 struct Sdl2Backend final : public BackendBase {
  52     Sdl2Backend(ALCdevice *device) noexcept : BackendBase{device} { }
  53     ~Sdl2Backend() override;
  54
  55     void audioCallback(Uint8 *stream, int len) noexcept;
  56     static void audioCallbackC(void *ptr, Uint8 *stream, int len) noexcept
  57     { static_cast<Sdl2Backend*>(ptr)->audioCallback(stream, len); }
  58
  59     void open(const ALCchar *name) override;
  60     bool reset() override;
  61     void start() override;
  62     void stop() override;
  63
  64     SDL_AudioDeviceID mDeviceID{0u};
  65     ALuint mFrameSize{0};
  66
  67     ALuint mFrequency{0u};
  68     DevFmtChannels mFmtChans{};
  69     DevFmtType     mFmtType{};
  70     ALuint mUpdateSize{0u};
  71
  72     DEF_NEWDEL(Sdl2Backend)
  73 };
  74
  75 Sdl2Backend::~Sdl2Backend()
  76 {
  77     if(mDeviceID)
  78         SDL_CloseAudioDevice(mDeviceID);
  79     mDeviceID = 0;
  80 }
  81
  82 void Sdl2Backend::audioCallback(Uint8 *stream, int len) noexcept
  83 {
  84     const auto ulen = static_cast<unsigned int>(len);
  85     assert((ulen % mFrameSize) == 0);
  86     mDevice->renderSamples(stream, ulen / mFrameSize, mDevice->channelsFromFmt());
  87 }
  88
  89 void Sdl2Backend::open(const ALCchar *name)
  90 {
  91     SDL_AudioSpec want{}, have{};
  92
  93     want.freq = static_cast<int>(mDevice->Frequency);
  94     switch(mDevice->FmtType)
  95     {
  96     case DevFmtUByte: want.format = AUDIO_U8; break;
  97     case DevFmtByte: want.format = AUDIO_S8; break;
  98     case DevFmtUShort: want.format = AUDIO_U16SYS; break;
  99     case DevFmtShort: want.format = AUDIO_S16SYS; break;
 100     case DevFmtUInt: /* fall-through */
 101     case DevFmtInt: want.format = AUDIO_S32SYS; break;
 102     case DevFmtFloat: want.format = AUDIO_F32; break;
 103     }
 104     want.channels = (mDevice->FmtChans == DevFmtMono) ? 1 : 2;
 105     want.samples = static_cast<Uint16>(mDevice->UpdateSize);
 106     want.callback = &Sdl2Backend::audioCallbackC;
 107     want.userdata = this;
 108
 109     /* Passing nullptr to SDL_OpenAudioDevice opens a default, which isn't
 110      * necessarily the first in the list.
 111      */
 112     if(!name || strcmp(name, defaultDeviceName) == 0)
 113         mDeviceID = SDL_OpenAudioDevice(nullptr, SDL_FALSE, &want, &have,
 114             SDL_AUDIO_ALLOW_ANY_CHANGE);
 115     else
 116     {
 117         const size_t prefix_len = strlen(DEVNAME_PREFIX);
 118         if(strncmp(name, DEVNAME_PREFIX, prefix_len) == 0)
 119             mDeviceID = SDL_OpenAudioDevice(name+prefix_len, SDL_FALSE, &want, &have,
 120                 SDL_AUDIO_ALLOW_ANY_CHANGE);
 121         else
 122             mDeviceID = SDL_OpenAudioDevice(name, SDL_FALSE, &want, &have,
 123                 SDL_AUDIO_ALLOW_ANY_CHANGE);
 124     }
 125     if(mDeviceID == 0)
 126         throw al::backend_exception{ALC_INVALID_VALUE, "%s", SDL_GetError()};
 127
 128     mDevice->Frequency = static_cast<ALuint>(have.freq);
 129
 130     if(have.channels == 1)
 131         mDevice->FmtChans = DevFmtMono;
 132     else if(have.channels == 2)
 133         mDevice->FmtChans = DevFmtStereo;
 134     else
 135         throw al::backend_exception{ALC_INVALID_VALUE, "Unhandled SDL channel count: %d",
 136             int{have.channels}};
 137
 138     switch(have.format)
 139     {
 140     case AUDIO_U8:     mDevice->FmtType = DevFmtUByte;  break;
 141     case AUDIO_S8:     mDevice->FmtType = DevFmtByte;   break;
 142     case AUDIO_U16SYS: mDevice->FmtType = DevFmtUShort; break;
 143     case AUDIO_S16SYS: mDevice->FmtType = DevFmtShort;  break;
 144     case AUDIO_S32SYS: mDevice->FmtType = DevFmtInt;    break;
 145     case AUDIO_F32SYS: mDevice->FmtType = DevFmtFloat;  break;
 146     default:
 147         throw al::backend_exception{ALC_INVALID_VALUE, "Unhandled SDL format: 0x%04x",
 148             have.format};
 149     }
 150     mDevice->UpdateSize = have.samples;
 151     mDevice->BufferSize = have.samples * 2; /* SDL always (tries to) use two periods. */
 152
 153     mFrameSize = mDevice->frameSizeFromFmt();
 154     mFrequency = mDevice->Frequency;
 155     mFmtChans = mDevice->FmtChans;
 156     mFmtType = mDevice->FmtType;
 157     mUpdateSize = mDevice->UpdateSize;
 158
 159     mDevice->DeviceName = name ? name : defaultDeviceName;
 160 }
 161
 162 bool Sdl2Backend::reset()
 163 {
 164     mDevice->Frequency = mFrequency;
 165     mDevice->FmtChans = mFmtChans;
 166     mDevice->FmtType = mFmtType;
 167     mDevice->UpdateSize = mUpdateSize;
 168     mDevice->BufferSize = mUpdateSize * 2;
 169     setDefaultWFXChannelOrder();
 170     return true;
 171 }
 172
 173 void Sdl2Backend::start()
 174 { SDL_PauseAudioDevice(mDeviceID, 0); }
 175
 176 void Sdl2Backend::stop()
 177 { SDL_PauseAudioDevice(mDeviceID, 1); }
 178
 179 } // namespace
 180
 181 BackendFactory &SDL2BackendFactory::getFactory()
 182 {
 183     static SDL2BackendFactory factory{};
 184     return factory;
 185 }
 186
 187 bool SDL2BackendFactory::init()
 188 { return (SDL_InitSubSystem(SDL_INIT_AUDIO) == 0); }
 189
 190 bool SDL2BackendFactory::querySupport(BackendType type)
 191 { return type == BackendType::Playback; }
 192
 193 std::string SDL2BackendFactory::probe(BackendType type)
 194 {
 195     std::string outnames;
 196
 197     if(type != BackendType::Playback)
 198         return outnames;
 199
 200     int num_devices{SDL_GetNumAudioDevices(SDL_FALSE)};
 201
 202     /* Includes null char. */
 203     outnames.append(defaultDeviceName, sizeof(defaultDeviceName));
 204     for(int i{0};i < num_devices;++i)
 205     {
 206         std::string name{DEVNAME_PREFIX};
 207         name += SDL_GetAudioDeviceName(i, SDL_FALSE);
 208         if(!name.empty())
 209             outnames.append(name.c_str(), name.length()+1);
 210     }
 211     return outnames;
 212 }
 213
 214 BackendPtr SDL2BackendFactory::createBackend(ALCdevice *device, BackendType type)
 215 {
 216     if(type == BackendType::Playback)
 217         return BackendPtr{new Sdl2Backend{device}};
 218     return nullptr;
 219 }