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213
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1 /*
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2 * SDL_sound -- An abstract sound format decoding API.
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3 * Copyright (C) 2001 Ryan C. Gordon.
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4 *
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5 * This library is free software; you can redistribute it and/or
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6 * modify it under the terms of the GNU Lesser General Public
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7 * License as published by the Free Software Foundation; either
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8 * version 2.1 of the License, or (at your option) any later version.
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9 *
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10 * This library is distributed in the hope that it will be useful,
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11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 * Lesser General Public License for more details.
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14 *
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15 * You should have received a copy of the GNU Lesser General Public
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16 * License along with this library; if not, write to the Free Software
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17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18 */
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19
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20 /*
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21 * Sun/NeXT .au decoder for SDL_sound.
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22 * Formats supported: 8 and 16 bit linear PCM, 8 bit µ-law.
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23 * Files without valid header are assumed to be 8 bit µ-law, 8kHz, mono.
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24 *
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25 * Please see the file COPYING in the source's root directory.
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26 *
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27 * This file written by Mattias Engdegĺrd. (f91-men@nada.kth.se)
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28 */
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29
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30 #if HAVE_CONFIG_H
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31 # include <config.h>
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32 #endif
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33
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34 #ifdef SOUND_SUPPORTS_AU
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35
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36 #include <stdio.h>
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37 #include <stdlib.h>
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38 #include <string.h>
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39 #include <assert.h>
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40
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41 #include "SDL_sound.h"
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42
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43 #define __SDL_SOUND_INTERNAL__
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44 #include "SDL_sound_internal.h"
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45
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46 static int AU_init(void);
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47 static void AU_quit(void);
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48 static int AU_open(Sound_Sample *sample, const char *ext);
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49 static void AU_close(Sound_Sample *sample);
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50 static Uint32 AU_read(Sound_Sample *sample);
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51
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52 /*
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53 * Sometimes the extension ".snd" is used for these files (mostly on the NeXT),
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54 * and the magic number comes from this. However it may clash with other
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55 * formats and is somewhat of an anachronism, so only .au is used here.
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56 */
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57 static const char *extensions_au[] = { "AU", NULL };
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58 const Sound_DecoderFunctions __Sound_DecoderFunctions_AU =
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59 {
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60 {
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61 extensions_au,
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62 "Sun/NeXT audio file format",
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63 "Mattias Engdegĺrd <f91-men@nada.kth.se>",
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64 "http://www.icculus.org/SDL_sound/"
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65 },
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66
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67 AU_init,
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68 AU_quit,
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69 AU_open,
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70 AU_close,
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71 AU_read
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72 };
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73
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74 /* no init/deinit needed */
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75 static int AU_init(void)
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76 {
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77 return(1);
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78 }
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79
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80 static void AU_quit(void)
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81 {
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82 /* no-op. */
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83 }
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84
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85 struct au_file_hdr
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86 {
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87 Uint32 magic;
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88 Uint32 hdr_size;
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89 Uint32 data_size;
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90 Uint32 encoding;
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91 Uint32 sample_rate;
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92 Uint32 channels;
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93 };
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94
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95 #define HDR_SIZE 24
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96
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97 enum
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98 {
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99 AU_ENC_ULAW_8 = 1, /* 8-bit ISDN µ-law */
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100 AU_ENC_LINEAR_8 = 2, /* 8-bit linear PCM */
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101 AU_ENC_LINEAR_16 = 3, /* 16-bit linear PCM */
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102
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103 /* the rest are unsupported (I have never seen them in the wild) */
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104 AU_ENC_LINEAR_24 = 4, /* 24-bit linear PCM */
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105 AU_ENC_LINEAR_32 = 5, /* 32-bit linear PCM */
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106 AU_ENC_FLOAT = 6, /* 32-bit IEEE floating point */
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107 AU_ENC_DOUBLE = 7, /* 64-bit IEEE floating point */
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108 /* more Sun formats, not supported either */
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109 AU_ENC_ADPCM_G721 = 23,
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110 AU_ENC_ADPCM_G722 = 24,
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111 AU_ENC_ADPCM_G723_3 = 25,
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112 AU_ENC_ADPCM_G723_5 = 26,
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113 AU_ENC_ALAW_8 = 27
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114 };
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115
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116 struct audec
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117 {
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118 unsigned remaining;
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119 int encoding;
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120 };
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121
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122
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123 #define AU_MAGIC 0x646E732E /* ".snd", in ASCII */
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124
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125 static int AU_open(Sound_Sample *sample, const char *ext)
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126 {
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127 Sound_SampleInternal *internal = sample->opaque;
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128 SDL_RWops *rw = internal->rw;
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129 int r, skip, hsize, i;
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130 struct au_file_hdr hdr;
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131 char c;
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132 struct audec *dec = malloc(sizeof *dec);
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133 BAIL_IF_MACRO(dec == NULL, ERR_OUT_OF_MEMORY, 0);
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134 internal->decoder_private = dec;
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135
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136 r = SDL_RWread(rw, &hdr, 1, HDR_SIZE);
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137 if (r < HDR_SIZE)
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138 {
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139 Sound_SetError("No .au file (bad header)");
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140 free(dec);
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141 return 0;
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142 }
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143
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144 if (SDL_SwapLE32(hdr.magic) == AU_MAGIC)
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145 {
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146 /* valid magic */
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147 dec->encoding = SDL_SwapBE32(hdr.encoding);
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148 switch(dec->encoding)
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149 {
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150 case AU_ENC_ULAW_8:
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151 /* Convert 8-bit µ-law to 16-bit linear on the fly. This is
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152 slightly wasteful if the audio driver must convert them
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153 back, but µ-law only devices are rare (mostly _old_ Suns) */
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154 sample->actual.format = AUDIO_S16SYS;
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155 break;
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156
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157 case AU_ENC_LINEAR_8:
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158 sample->actual.format = AUDIO_S8;
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159 break;
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160
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161 case AU_ENC_LINEAR_16:
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162 sample->actual.format = AUDIO_S16MSB;
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163 break;
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164
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165 default:
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166 Sound_SetError("Unsupported .au encoding");
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167 free(dec);
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168 return 0;
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169 }
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170
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171 sample->actual.rate = SDL_SwapBE32(hdr.sample_rate);
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172 sample->actual.channels = SDL_SwapBE32(hdr.channels);
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173 dec->remaining = SDL_SwapBE32(hdr.data_size);
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174 hsize = SDL_SwapBE32(hdr.hdr_size);
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175
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176 /* skip remaining part of header (input may be unseekable) */
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177 for (i = HDR_SIZE; i < hsize; i++)
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178 SDL_RWread(rw, &c, 1, 1);
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179 }
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180
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181 else if (__Sound_strcasecmp(ext, "au") == 0)
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182 {
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183 /*
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184 * A number of files in the wild have the .au extension but no valid
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185 * header; these are traditionally assumed to be 8kHz µ-law. Handle
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186 * them here only if the extension is recognized.
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187 */
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188
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189 SNDDBG(("AU: Invalid header, assuming raw 8kHz µ-law.\n"));
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190 /* if seeking fails, we lose 24 samples. big deal */
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191 SDL_RWseek(rw, -HDR_SIZE, SEEK_CUR);
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192 dec->encoding = AU_ENC_ULAW_8;
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193 dec->remaining = (Uint32)-1; /* no limit */
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194 sample->actual.format = AUDIO_S16SYS;
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195 sample->actual.rate = 8000;
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196 sample->actual.channels = 1;
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197 }
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198
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199 sample->flags = SOUND_SAMPLEFLAG_NONE;
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200
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201 SNDDBG(("AU: Accepting data stream.\n"));
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202 return 1;
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203 }
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204
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205
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206 static void AU_close(Sound_Sample *sample)
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207 {
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208 Sound_SampleInternal *internal = sample->opaque;
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209 free(internal->decoder_private);
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210 }
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211
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212 /* table to convert from µ-law encoding to signed 16-bit samples,
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213 generated by a throwaway perl script */
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214 static Sint16 ulaw_to_linear[256] = {
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215 -32124,-31100,-30076,-29052,-28028,-27004,-25980,-24956,
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216 -23932,-22908,-21884,-20860,-19836,-18812,-17788,-16764,
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217 -15996,-15484,-14972,-14460,-13948,-13436,-12924,-12412,
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218 -11900,-11388,-10876,-10364, -9852, -9340, -8828, -8316,
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219 -7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140,
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220 -5884, -5628, -5372, -5116, -4860, -4604, -4348, -4092,
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221 -3900, -3772, -3644, -3516, -3388, -3260, -3132, -3004,
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222 -2876, -2748, -2620, -2492, -2364, -2236, -2108, -1980,
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223 -1884, -1820, -1756, -1692, -1628, -1564, -1500, -1436,
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224 -1372, -1308, -1244, -1180, -1116, -1052, -988, -924,
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225 -876, -844, -812, -780, -748, -716, -684, -652,
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226 -620, -588, -556, -524, -492, -460, -428, -396,
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227 -372, -356, -340, -324, -308, -292, -276, -260,
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228 -244, -228, -212, -196, -180, -164, -148, -132,
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229 -120, -112, -104, -96, -88, -80, -72, -64,
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230 -56, -48, -40, -32, -24, -16, -8, 0,
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231 32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956,
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232 23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764,
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233 15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412,
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234 11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316,
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235 7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140,
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236 5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092,
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237 3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004,
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238 2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980,
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239 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436,
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240 1372, 1308, 1244, 1180, 1116, 1052, 988, 924,
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241 876, 844, 812, 780, 748, 716, 684, 652,
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242 620, 588, 556, 524, 492, 460, 428, 396,
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243 372, 356, 340, 324, 308, 292, 276, 260,
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244 244, 228, 212, 196, 180, 164, 148, 132,
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245 120, 112, 104, 96, 88, 80, 72, 64,
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246 56, 48, 40, 32, 24, 16, 8, 0
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247 };
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248
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249 static Uint32 AU_read(Sound_Sample *sample)
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250 {
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251 int ret;
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252 Sound_SampleInternal *internal = sample->opaque;
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253 struct audec *dec = internal->decoder_private;
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254 int maxlen;
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255 Uint8 *buf;
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256
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257 maxlen = internal->buffer_size;
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258 buf = internal->buffer;
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259 if (dec->encoding == AU_ENC_ULAW_8)
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260 {
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261 /* We read µ-law samples into the second half of the buffer, so
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262 we can expand them to 16-bit samples afterwards */
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263 maxlen >>= 1;
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264 buf += maxlen;
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265 }
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266
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267 if(maxlen > dec->remaining)
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268 maxlen = dec->remaining;
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269 ret = SDL_RWread(internal->rw, buf, 1, maxlen);
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270 if (ret == 0)
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271 sample->flags |= SOUND_SAMPLEFLAG_EOF;
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272 else if (ret == -1)
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273 sample->flags |= SOUND_SAMPLEFLAG_ERROR;
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274 else
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275 {
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276 dec->remaining -= ret;
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277 if (ret < maxlen)
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278 sample->flags |= SOUND_SAMPLEFLAG_EAGAIN;
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279
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280 if (dec->encoding == AU_ENC_ULAW_8)
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281 {
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282 int i;
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283 Sint16 *dst = internal->buffer;
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284 for (i = 0; i < ret; i++)
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285 dst[i] = ulaw_to_linear[buf[i]];
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286 ret <<= 1; /* return twice as much as read */
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287 }
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288 }
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289
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290 return ret;
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291 }
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292
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293 #endif /* SOUND_SUPPORTS_AU */
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294
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