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 #include <SDL2/SDL.h>
  36
  37
  38 namespace {
  39
  40 #ifdef _WIN32
  41 #define DEVNAME_PREFIX "OpenAL Soft on "
  42 #else
  43 #define DEVNAME_PREFIX ""
  44 #endif
  45
  46 constexpr char defaultDeviceName[] = DEVNAME_PREFIX "Default Device";
  47
  48 struct Sdl2Backend final : public BackendBase {
  49     Sdl2Backend(DeviceBase *device) noexcept : BackendBase{device} { }
  50     ~Sdl2Backend() override;
  51
  52     void audioCallback(Uint8 *stream, int len) noexcept;
  53     static void audioCallbackC(void *ptr, Uint8 *stream, int len) noexcept
  54     { static_cast<Sdl2Backend*>(ptr)->audioCallback(stream, len); }
  55
  56     void open(const char *name) override;
  57     bool reset() override;
  58     void start() override;
  59     void stop() override;
  60
  61     SDL_AudioDeviceID mDeviceID{0u};
  62     uint mFrameSize{0};
  63
  64     uint mFrequency{0u};
  65     DevFmtChannels mFmtChans{};
  66     DevFmtType     mFmtType{};
  67     uint mUpdateSize{0u};
  68
  69     DEF_NEWDEL(Sdl2Backend)
  70 };
  71
  72 Sdl2Backend::~Sdl2Backend()
  73 {
  74     if(mDeviceID)
  75         SDL_CloseAudioDevice(mDeviceID);
  76     mDeviceID = 0;
  77 }
  78
  79 void Sdl2Backend::audioCallback(Uint8 *stream, int len) noexcept
  80 {
  81     const auto ulen = static_cast<unsigned int>(len);
  82     assert((ulen % mFrameSize) == 0);
  83     mDevice->renderSamples(stream, ulen / mFrameSize, mDevice->channelsFromFmt());
  84 }
  85
  86 void Sdl2Backend::open(const char *name)
  87 {
  88     SDL_AudioSpec want{}, have{};
  89
  90     want.freq = static_cast<int>(mDevice->Frequency);
  91     switch(mDevice->FmtType)
  92     {
  93     case DevFmtUByte: want.format = AUDIO_U8; break;
  94     case DevFmtByte: want.format = AUDIO_S8; break;
  95     case DevFmtUShort: want.format = AUDIO_U16SYS; break;
  96     case DevFmtShort: want.format = AUDIO_S16SYS; break;
  97     case DevFmtUInt: /* fall-through */
  98     case DevFmtInt: want.format = AUDIO_S32SYS; break;
  99     case DevFmtFloat: want.format = AUDIO_F32; break;
 100     }
 101     want.channels = (mDevice->FmtChans == DevFmtMono) ? 1 : 2;
 102     want.samples = static_cast<Uint16>(minu(mDevice->UpdateSize, 8192));
 103     want.callback = &Sdl2Backend::audioCallbackC;
 104     want.userdata = this;
 105
 106     /* Passing nullptr to SDL_OpenAudioDevice opens a default, which isn't
 107      * necessarily the first in the list.
 108      */
 109     SDL_AudioDeviceID devid;
 110     if(!name || strcmp(name, defaultDeviceName) == 0)
 111         devid = SDL_OpenAudioDevice(nullptr, SDL_FALSE, &want, &have, SDL_AUDIO_ALLOW_ANY_CHANGE);
 112     else
 113     {
 114         const size_t prefix_len = strlen(DEVNAME_PREFIX);
 115         if(strncmp(name, DEVNAME_PREFIX, prefix_len) == 0)
 116             devid = SDL_OpenAudioDevice(name+prefix_len, SDL_FALSE, &want, &have,
 117                 SDL_AUDIO_ALLOW_ANY_CHANGE);
 118         else
 119             devid = SDL_OpenAudioDevice(name, SDL_FALSE, &want, &have, SDL_AUDIO_ALLOW_ANY_CHANGE);
 120     }
 121     if(!devid)
 122         throw al::backend_exception{al::backend_error::NoDevice, "%s", SDL_GetError()};
 123
 124     DevFmtChannels devchans{};
 125     if(have.channels >= 2)
 126         devchans = DevFmtStereo;
 127     else if(have.channels == 1)
 128         devchans = DevFmtMono;
 129     else
 130     {
 131         SDL_CloseAudioDevice(devid);
 132         throw al::backend_exception{al::backend_error::DeviceError,
 133             "Unhandled SDL channel count: %d", int{have.channels}};
 134     }
 135
 136     DevFmtType devtype{};
 137     switch(have.format)
 138     {
 139     case AUDIO_U8:     devtype = DevFmtUByte;  break;
 140     case AUDIO_S8:     devtype = DevFmtByte;   break;
 141     case AUDIO_U16SYS: devtype = DevFmtUShort; break;
 142     case AUDIO_S16SYS: devtype = DevFmtShort;  break;
 143     case AUDIO_S32SYS: devtype = DevFmtInt;    break;
 144     case AUDIO_F32SYS: devtype = DevFmtFloat;  break;
 145     default:
 146         SDL_CloseAudioDevice(devid);
 147         throw al::backend_exception{al::backend_error::DeviceError, "Unhandled SDL format: 0x%04x",
 148             have.format};
 149     }
 150
 151     if(mDeviceID)
 152         SDL_CloseAudioDevice(mDeviceID);
 153     mDeviceID = devid;
 154
 155     mFrameSize = BytesFromDevFmt(devtype) * have.channels;
 156     mFrequency = static_cast<uint>(have.freq);
 157     mFmtChans = devchans;
 158     mFmtType = devtype;
 159     mUpdateSize = have.samples;
 160
 161     mDevice->DeviceName = name ? name : defaultDeviceName;
 162 }
 163
 164 bool Sdl2Backend::reset()
 165 {
 166     mDevice->Frequency = mFrequency;
 167     mDevice->FmtChans = mFmtChans;
 168     mDevice->FmtType = mFmtType;
 169     mDevice->UpdateSize = mUpdateSize;
 170     mDevice->BufferSize = mUpdateSize * 2; /* SDL always (tries to) use two periods. */
 171     setDefaultWFXChannelOrder();
 172     return true;
 173 }
 174
 175 void Sdl2Backend::start()
 176 { SDL_PauseAudioDevice(mDeviceID, 0); }
 177
 178 void Sdl2Backend::stop()
 179 { SDL_PauseAudioDevice(mDeviceID, 1); }
 180
 181 } // namespace
 182
 183 BackendFactory &SDL2BackendFactory::getFactory()
 184 {
 185     static SDL2BackendFactory factory{};
 186     return factory;
 187 }
 188
 189 bool SDL2BackendFactory::init()
 190 { return (SDL_InitSubSystem(SDL_INIT_AUDIO) == 0); }
 191
 192 bool SDL2BackendFactory::querySupport(BackendType type)
 193 { return type == BackendType::Playback; }
 194
 195 std::string SDL2BackendFactory::probe(BackendType type)
 196 {
 197     std::string outnames;
 198
 199     if(type != BackendType::Playback)
 200         return outnames;
 201
 202     int num_devices{SDL_GetNumAudioDevices(SDL_FALSE)};
 203
 204     /* Includes null char. */
 205     outnames.append(defaultDeviceName, sizeof(defaultDeviceName));
 206     for(int i{0};i < num_devices;++i)
 207     {
 208         std::string name{DEVNAME_PREFIX};
 209         name += SDL_GetAudioDeviceName(i, SDL_FALSE);
 210         if(!name.empty())
 211             outnames.append(name.c_str(), name.length()+1);
 212     }
 213     return outnames;
 214 }
 215
 216 BackendPtr SDL2BackendFactory::createBackend(DeviceBase *device, BackendType type)
 217 {
 218     if(type == BackendType::Playback)
 219         return BackendPtr{new Sdl2Backend{device}};
 220     return nullptr;
 221 }