examples/common/sdl_sound.c

   1 /*
   2  * SDL_sound Decoder Helpers
   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 routines for helping to decode audio using SDL_sound.
  26  * There's very little OpenAL-specific code here.
  27  */
  28 #include "sdl_sound.h"
  29
  30 #include <string.h>
  31 #include <stdlib.h>
  32 #include <stdio.h>
  33 #include <signal.h>
  34 #include <assert.h>
  35
  36 #include <SDL_sound.h>
  37
  38 #include "AL/al.h"
  39 #include "AL/alc.h"
  40 #include "AL/alext.h"
  41
  42 #include "alhelpers.h"
  43
  44
  45 static int done_init = 0;
  46
  47 FilePtr openAudioFile(const char *fname, size_t buftime_ms)
  48 {
  49     FilePtr file;
  50     ALuint rate;
  51     Uint32 bufsize;
  52     ALenum chans, type;
  53
  54     /* We need to make sure SDL_sound is initialized. */
  55     if(!done_init)
  56     {
  57         Sound_Init();
  58         done_init = 1;
  59     }
  60
  61     file = Sound_NewSampleFromFile(fname, NULL, 0);
  62     if(!file)
  63     {
  64         fprintf(stderr, "Failed to open %s: %s\n", fname, Sound_GetError());
  65         return NULL;
  66     }
  67
  68     if(getAudioInfo(file, &rate, &chans, &type) != 0)
  69     {
  70         Sound_FreeSample(file);
  71         return NULL;
  72     }
  73
  74     bufsize = FramesToBytes((ALsizei)(buftime_ms/1000.0*rate), chans, type);
  75     if(Sound_SetBufferSize(file, bufsize) == 0)
  76     {
  77         fprintf(stderr, "Failed to set buffer size to %u bytes: %s\n", bufsize, Sound_GetError());
  78         Sound_FreeSample(file);
  79         return NULL;
  80     }
  81
  82     return file;
  83 }
  84
  85 void closeAudioFile(FilePtr file)
  86 {
  87     if(file)
  88         Sound_FreeSample(file);
  89 }
  90
  91
  92 int getAudioInfo(FilePtr file, ALuint *rate, ALenum *channels, ALenum *type)
  93 {
  94     if(file->actual.channels == 1)
  95         *channels = AL_MONO_SOFT;
  96     else if(file->actual.channels == 2)
  97         *channels = AL_STEREO_SOFT;
  98     else
  99     {
 100         fprintf(stderr, "Unsupported channel count: %d\n", file->actual.channels);
 101         return 1;
 102     }
 103
 104     if(file->actual.format == AUDIO_U8)
 105         *type = AL_UNSIGNED_BYTE_SOFT;
 106     else if(file->actual.format == AUDIO_S8)
 107         *type = AL_BYTE_SOFT;
 108     else if(file->actual.format == AUDIO_U16LSB || file->actual.format == AUDIO_U16MSB)
 109         *type = AL_UNSIGNED_SHORT_SOFT;
 110     else if(file->actual.format == AUDIO_S16LSB || file->actual.format == AUDIO_S16MSB)
 111         *type = AL_SHORT_SOFT;
 112     else
 113     {
 114         fprintf(stderr, "Unsupported sample format: 0x%04x\n", file->actual.format);
 115         return 1;
 116     }
 117
 118     *rate = file->actual.rate;
 119
 120     return 0;
 121 }
 122
 123
 124 uint8_t *getAudioData(FilePtr file, size_t *length)
 125 {
 126     *length = Sound_Decode(file);
 127     if(*length == 0)
 128         return NULL;
 129     if((file->actual.format == AUDIO_U16LSB && AUDIO_U16LSB != AUDIO_U16SYS) ||
 130        (file->actual.format == AUDIO_U16MSB && AUDIO_U16MSB != AUDIO_U16SYS) ||
 131        (file->actual.format == AUDIO_S16LSB && AUDIO_S16LSB != AUDIO_S16SYS) ||
 132        (file->actual.format == AUDIO_S16MSB && AUDIO_S16MSB != AUDIO_S16SYS))
 133     {
 134         /* Swap bytes if the decoded endianness doesn't match the system. */
 135         char *buffer = file->buffer;
 136         size_t i;
 137         for(i = 0;i < *length;i+=2)
 138         {
 139             char b = buffer[i];
 140             buffer[i] = buffer[i+1];
 141             buffer[i+1] = b;
 142         }
 143     }
 144     return file->buffer;
 145 }
 146
 147 void *decodeAudioStream(FilePtr file, size_t *length)
 148 {
 149     Uint32 got;
 150     char *mem;
 151
 152     got = Sound_DecodeAll(file);
 153     if(got == 0)
 154     {
 155         *length = 0;
 156         return NULL;
 157     }
 158
 159     mem = malloc(got);
 160     memcpy(mem, file->buffer, got);
 161
 162     *length = got;
 163     return mem;
 164 }