examples/alloopback.c

   1 /*
   2  * OpenAL Loopback Example
   3  *
   4  * Copyright (c) 2013 by Chris Robinson <chris.kcat@gmail.com>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 /* This file contains an example for using the loopback device for custom
  26  * output handling.
  27  */
  28
  29 #include <assert.h>
  30 #include <math.h>
  31 #include <stdio.h>
  32
  33 #define SDL_MAIN_HANDLED
  34 #include "SDL.h"
  35 #include "SDL_audio.h"
  36 #include "SDL_error.h"
  37 #include "SDL_stdinc.h"
  38
  39 #include "AL/al.h"
  40 #include "AL/alc.h"
  41 #include "AL/alext.h"
  42
  43 #include "common/alhelpers.h"
  44
  45 #ifndef SDL_AUDIO_MASK_BITSIZE
  46 #define SDL_AUDIO_MASK_BITSIZE (0xFF)
  47 #endif
  48 #ifndef SDL_AUDIO_BITSIZE
  49 #define SDL_AUDIO_BITSIZE(x) (x & SDL_AUDIO_MASK_BITSIZE)
  50 #endif
  51
  52 #ifndef M_PI
  53 #define M_PI    (3.14159265358979323846)
  54 #endif
  55
  56 typedef struct {
  57     ALCdevice *Device;
  58     ALCcontext *Context;
  59
  60     ALCsizei FrameSize;
  61 } PlaybackInfo;
  62
  63 static LPALCLOOPBACKOPENDEVICESOFT alcLoopbackOpenDeviceSOFT;
  64 static LPALCISRENDERFORMATSUPPORTEDSOFT alcIsRenderFormatSupportedSOFT;
  65 static LPALCRENDERSAMPLESSOFT alcRenderSamplesSOFT;
  66
  67
  68 void SDLCALL RenderSDLSamples(void *userdata, Uint8 *stream, int len)
  69 {
  70     PlaybackInfo *playback = (PlaybackInfo*)userdata;
  71     alcRenderSamplesSOFT(playback->Device, stream, len/playback->FrameSize);
  72 }
  73
  74
  75 static const char *ChannelsName(ALCenum chans)
  76 {
  77     switch(chans)
  78     {
  79     case ALC_MONO_SOFT: return "Mono";
  80     case ALC_STEREO_SOFT: return "Stereo";
  81     case ALC_QUAD_SOFT: return "Quadraphonic";
  82     case ALC_5POINT1_SOFT: return "5.1 Surround";
  83     case ALC_6POINT1_SOFT: return "6.1 Surround";
  84     case ALC_7POINT1_SOFT: return "7.1 Surround";
  85     }
  86     return "Unknown Channels";
  87 }
  88
  89 static const char *TypeName(ALCenum type)
  90 {
  91     switch(type)
  92     {
  93     case ALC_BYTE_SOFT: return "S8";
  94     case ALC_UNSIGNED_BYTE_SOFT: return "U8";
  95     case ALC_SHORT_SOFT: return "S16";
  96     case ALC_UNSIGNED_SHORT_SOFT: return "U16";
  97     case ALC_INT_SOFT: return "S32";
  98     case ALC_UNSIGNED_INT_SOFT: return "U32";
  99     case ALC_FLOAT_SOFT: return "Float32";
 100     }
 101     return "Unknown Type";
 102 }
 103
 104 /* Creates a one second buffer containing a sine wave, and returns the new
 105  * buffer ID. */
 106 static ALuint CreateSineWave(void)
 107 {
 108     ALshort data[44100*4];
 109     ALuint buffer;
 110     ALenum err;
 111     ALuint i;
 112
 113     for(i = 0;i < 44100*4;i++)
 114         data[i] = (ALshort)(sin(i/44100.0 * 1000.0 * 2.0*M_PI) * 32767.0);
 115
 116     /* Buffer the audio data into a new buffer object. */
 117     buffer = 0;
 118     alGenBuffers(1, &buffer);
 119     alBufferData(buffer, AL_FORMAT_MONO16, data, sizeof(data), 44100);
 120
 121     /* Check if an error occured, and clean up if so. */
 122     err = alGetError();
 123     if(err != AL_NO_ERROR)
 124     {
 125         fprintf(stderr, "OpenAL Error: %s\n", alGetString(err));
 126         if(alIsBuffer(buffer))
 127             alDeleteBuffers(1, &buffer);
 128         return 0;
 129     }
 130
 131     return buffer;
 132 }
 133
 134
 135 int main(int argc, char *argv[])
 136 {
 137     PlaybackInfo playback = { NULL, NULL, 0 };
 138     SDL_AudioSpec desired, obtained;
 139     ALuint source, buffer;
 140     ALCint attrs[16];
 141     ALenum state;
 142     (void)argc;
 143     (void)argv;
 144
 145     SDL_SetMainReady();
 146
 147     /* Print out error if extension is missing. */
 148     if(!alcIsExtensionPresent(NULL, "ALC_SOFT_loopback"))
 149     {
 150         fprintf(stderr, "Error: ALC_SOFT_loopback not supported!\n");
 151         return 1;
 152     }
 153
 154     /* Define a macro to help load the function pointers. */
 155 #define LOAD_PROC(T, x)  ((x) = FUNCTION_CAST(T, alcGetProcAddress(NULL, #x)))
 156     LOAD_PROC(LPALCLOOPBACKOPENDEVICESOFT, alcLoopbackOpenDeviceSOFT);
 157     LOAD_PROC(LPALCISRENDERFORMATSUPPORTEDSOFT, alcIsRenderFormatSupportedSOFT);
 158     LOAD_PROC(LPALCRENDERSAMPLESSOFT, alcRenderSamplesSOFT);
 159 #undef LOAD_PROC
 160
 161     if(SDL_Init(SDL_INIT_AUDIO) == -1)
 162     {
 163         fprintf(stderr, "Failed to init SDL audio: %s\n", SDL_GetError());
 164         return 1;
 165     }
 166
 167     /* Set up SDL audio with our requested format and callback. */
 168     desired.channels = 2;
 169     desired.format = AUDIO_S16SYS;
 170     desired.freq = 44100;
 171     desired.padding = 0;
 172     desired.samples = 4096;
 173     desired.callback = RenderSDLSamples;
 174     desired.userdata = &playback;
 175     if(SDL_OpenAudio(&desired, &obtained) != 0)
 176     {
 177         SDL_Quit();
 178         fprintf(stderr, "Failed to open SDL audio: %s\n", SDL_GetError());
 179         return 1;
 180     }
 181
 182     /* Set up our OpenAL attributes based on what we got from SDL. */
 183     attrs[0] = ALC_FORMAT_CHANNELS_SOFT;
 184     if(obtained.channels == 1)
 185         attrs[1] = ALC_MONO_SOFT;
 186     else if(obtained.channels == 2)
 187         attrs[1] = ALC_STEREO_SOFT;
 188     else
 189     {
 190         fprintf(stderr, "Unhandled SDL channel count: %d\n", obtained.channels);
 191         goto error;
 192     }
 193
 194     attrs[2] = ALC_FORMAT_TYPE_SOFT;
 195     if(obtained.format == AUDIO_U8)
 196         attrs[3] = ALC_UNSIGNED_BYTE_SOFT;
 197     else if(obtained.format == AUDIO_S8)
 198         attrs[3] = ALC_BYTE_SOFT;
 199     else if(obtained.format == AUDIO_U16SYS)
 200         attrs[3] = ALC_UNSIGNED_SHORT_SOFT;
 201     else if(obtained.format == AUDIO_S16SYS)
 202         attrs[3] = ALC_SHORT_SOFT;
 203     else if(obtained.format == AUDIO_S32SYS)
 204         attrs[3] = ALC_INT_SOFT;
 205     else if(obtained.format == AUDIO_F32SYS)
 206         attrs[3] = ALC_FLOAT_SOFT;
 207     else
 208     {
 209         fprintf(stderr, "Unhandled SDL format: 0x%04x\n", obtained.format);
 210         goto error;
 211     }
 212
 213     attrs[4] = ALC_FREQUENCY;
 214     attrs[5] = obtained.freq;
 215
 216     attrs[6] = 0; /* end of list */
 217
 218     playback.FrameSize = obtained.channels * SDL_AUDIO_BITSIZE(obtained.format) / 8;
 219
 220     /* Initialize OpenAL loopback device, using our format attributes. */
 221     playback.Device = alcLoopbackOpenDeviceSOFT(NULL);
 222     if(!playback.Device)
 223     {
 224         fprintf(stderr, "Failed to open loopback device!\n");
 225         goto error;
 226     }
 227     /* Make sure the format is supported before setting them on the device. */
 228     if(alcIsRenderFormatSupportedSOFT(playback.Device, attrs[5], attrs[1], attrs[3]) == ALC_FALSE)
 229     {
 230         fprintf(stderr, "Render format not supported: %s, %s, %dhz\n",
 231                         ChannelsName(attrs[1]), TypeName(attrs[3]), attrs[5]);
 232         goto error;
 233     }
 234     playback.Context = alcCreateContext(playback.Device, attrs);
 235     if(!playback.Context || alcMakeContextCurrent(playback.Context) == ALC_FALSE)
 236     {
 237         fprintf(stderr, "Failed to set an OpenAL audio context\n");
 238         goto error;
 239     }
 240
 241     /* Start SDL playing. Our callback (thus alcRenderSamplesSOFT) will now
 242      * start being called regularly to update the AL playback state. */
 243     SDL_PauseAudio(0);
 244
 245     /* Load the sound into a buffer. */
 246     buffer = CreateSineWave();
 247     if(!buffer)
 248     {
 249         SDL_CloseAudio();
 250         alcDestroyContext(playback.Context);
 251         alcCloseDevice(playback.Device);
 252         SDL_Quit();
 253         return 1;
 254     }
 255
 256     /* Create the source to play the sound with. */
 257     source = 0;
 258     alGenSources(1, &source);
 259     alSourcei(source, AL_BUFFER, (ALint)buffer);
 260     assert(alGetError()==AL_NO_ERROR && "Failed to setup sound source");
 261
 262     /* Play the sound until it finishes. */
 263     alSourcePlay(source);
 264     do {
 265         al_nssleep(10000000);
 266         alGetSourcei(source, AL_SOURCE_STATE, &state);
 267     } while(alGetError() == AL_NO_ERROR && state == AL_PLAYING);
 268
 269     /* All done. Delete resources, and close OpenAL. */
 270     alDeleteSources(1, &source);
 271     alDeleteBuffers(1, &buffer);
 272
 273     /* Stop SDL playing. */
 274     SDL_PauseAudio(1);
 275
 276     /* Close up OpenAL and SDL. */
 277     SDL_CloseAudio();
 278     alcDestroyContext(playback.Context);
 279     alcCloseDevice(playback.Device);
 280     SDL_Quit();
 281
 282     return 0;
 283
 284 error:
 285     SDL_CloseAudio();
 286     if(playback.Context)
 287         alcDestroyContext(playback.Context);
 288     if(playback.Device)
 289         alcCloseDevice(playback.Device);
 290     SDL_Quit();
 291
 292     return 1;
 293 }