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 "sdl2.h"
  24
  25 #include <cassert>
  26 #include <cstdlib>
  27 #include <cstring>
  28 #include <string>
  29
  30 #include "almalloc.h"
  31 #include "alnumeric.h"
  32 #include "core/device.h"
  33 #include "core/logging.h"
  34
  35 _Pragma("GCC diagnostic push")
  36 _Pragma("GCC diagnostic ignored \"-Wold-style-cast\"")
  37 #include "SDL.h"
  38 _Pragma("GCC diagnostic pop")
  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 char defaultDeviceName[] = DEVNAME_PREFIX "Default Device";
  50
  51 struct Sdl2Backend final : public BackendBase {
  52     Sdl2Backend(DeviceBase *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 char *name) override;
  60     bool reset() override;
  61     void start() override;
  62     void stop() override;
  63
  64     SDL_AudioDeviceID mDeviceID{0u};
  65     uint mFrameSize{0};
  66
  67     uint mFrequency{0u};
  68     DevFmtChannels mFmtChans{};
  69     DevFmtType     mFmtType{};
  70     uint 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 char *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>(minu(mDevice->UpdateSize, 8192));
 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     SDL_AudioDeviceID devid;
 113     if(!name || strcmp(name, defaultDeviceName) == 0)
 114         devid = SDL_OpenAudioDevice(nullptr, SDL_FALSE, &want, &have, 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             devid = SDL_OpenAudioDevice(name+prefix_len, SDL_FALSE, &want, &have,
 120                 SDL_AUDIO_ALLOW_ANY_CHANGE);
 121         else
 122             devid = SDL_OpenAudioDevice(name, SDL_FALSE, &want, &have, SDL_AUDIO_ALLOW_ANY_CHANGE);
 123     }
 124     if(!devid)
 125         throw al::backend_exception{al::backend_error::NoDevice, "%s", SDL_GetError()};
 126
 127     DevFmtChannels devchans{};
 128     if(have.channels >= 2)
 129         devchans = DevFmtStereo;
 130     else if(have.channels == 1)
 131         devchans = DevFmtMono;
 132     else
 133     {
 134         SDL_CloseAudioDevice(devid);
 135         throw al::backend_exception{al::backend_error::DeviceError,
 136             "Unhandled SDL channel count: %d", int{have.channels}};
 137     }
 138
 139     DevFmtType devtype{};
 140     switch(have.format)
 141     {
 142     case AUDIO_U8:     devtype = DevFmtUByte;  break;
 143     case AUDIO_S8:     devtype = DevFmtByte;   break;
 144     case AUDIO_U16SYS: devtype = DevFmtUShort; break;
 145     case AUDIO_S16SYS: devtype = DevFmtShort;  break;
 146     case AUDIO_S32SYS: devtype = DevFmtInt;    break;
 147     case AUDIO_F32SYS: devtype = DevFmtFloat;  break;
 148     default:
 149         SDL_CloseAudioDevice(devid);
 150         throw al::backend_exception{al::backend_error::DeviceError, "Unhandled SDL format: 0x%04x",
 151             have.format};
 152     }
 153
 154     if(mDeviceID)
 155         SDL_CloseAudioDevice(mDeviceID);
 156     mDeviceID = devid;
 157
 158     mFrameSize = BytesFromDevFmt(devtype) * have.channels;
 159     mFrequency = static_cast<uint>(have.freq);
 160     mFmtChans = devchans;
 161     mFmtType = devtype;
 162     mUpdateSize = have.samples;
 163
 164     mDevice->DeviceName = name ? name : defaultDeviceName;
 165 }
 166
 167 bool Sdl2Backend::reset()
 168 {
 169     mDevice->Frequency = mFrequency;
 170     mDevice->FmtChans = mFmtChans;
 171     mDevice->FmtType = mFmtType;
 172     mDevice->UpdateSize = mUpdateSize;
 173     mDevice->BufferSize = mUpdateSize * 2; /* SDL always (tries to) use two periods. */
 174     setDefaultWFXChannelOrder();
 175     return true;
 176 }
 177
 178 void Sdl2Backend::start()
 179 { SDL_PauseAudioDevice(mDeviceID, 0); }
 180
 181 void Sdl2Backend::stop()
 182 { SDL_PauseAudioDevice(mDeviceID, 1); }
 183
 184 } // namespace
 185
 186 BackendFactory &SDL2BackendFactory::getFactory()
 187 {
 188     static SDL2BackendFactory factory{};
 189     return factory;
 190 }
 191
 192 bool SDL2BackendFactory::init()
 193 { return (SDL_InitSubSystem(SDL_INIT_AUDIO) == 0); }
 194
 195 bool SDL2BackendFactory::querySupport(BackendType type)
 196 { return type == BackendType::Playback; }
 197
 198 std::string SDL2BackendFactory::probe(BackendType type)
 199 {
 200     std::string outnames;
 201
 202     if(type != BackendType::Playback)
 203         return outnames;
 204
 205     int num_devices{SDL_GetNumAudioDevices(SDL_FALSE)};
 206
 207     /* Includes null char. */
 208     outnames.append(defaultDeviceName, sizeof(defaultDeviceName));
 209     for(int i{0};i < num_devices;++i)
 210     {
 211         std::string name{DEVNAME_PREFIX};
 212         name += SDL_GetAudioDeviceName(i, SDL_FALSE);
 213         if(!name.empty())
 214             outnames.append(name.c_str(), name.length()+1);
 215     }
 216     return outnames;
 217 }
 218
 219 BackendPtr SDL2BackendFactory::createBackend(DeviceBase *device, BackendType type)
 220 {
 221     if(type == BackendType::Playback)
 222         return BackendPtr{new Sdl2Backend{device}};
 223     return nullptr;
 224 }