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1 ## Copyright (C) 2005 Michael Zeising |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## 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 ## 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 General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {@var{y}} = wavread (@var{filename}) |
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22 ## Load the RIFF/WAVE sound file @var{filename}, and return the samples |
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23 ## in vector @var{y}. If the file contains multichannel data, then |
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24 ## @var{y} is a matrix with the channels represented as columns. |
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25 ## |
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26 ## @deftypefnx {Function File} {[@var{y}, @var{Fs}, @var{bits}]} = wavread (@var{filename}) |
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27 ## Additionally return the sample rate (@var{fs}) in Hz and the number of bits |
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28 ## per sample (@var{bits}). |
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29 ## |
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30 ## @deftypefnx {Function File} {[@dots{}]} = wavread (@var{filename}, @var{n}) |
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31 ## Read only the first @var{n} samples from each channel. |
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32 ## |
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33 ## @deftypefnx {Function File} {[@dots{}]} = wavread(@var{filename},[@var{n1} @var{n2}]) |
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34 ## Read only samples @var{n1} through @var{n2} from each channel. |
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35 ## |
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36 ## @deftypefnx {Function File} {[@var{samples}, @var{channels}]} = wavread (@var{filename}, "size") |
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37 ## Return the number of samples (@var{n}) and channels (@var{ch}) |
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38 ## instead of the audio data. |
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39 ## @end deftypefn |
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40 ## |
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41 ## @seealso{wavwrite} |
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42 |
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43 ## Author: Michael Zeising <michael.zeising@stud.uni-erlangen.de> |
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44 ## Created: 06 December 2005 |
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45 |
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46 function [y, samples_per_sec, bits_per_sample] = wavread (filename, param) |
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47 |
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48 FORMAT_PCM = 0x0001; # PCM (8/16/32 bit) |
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49 FORMAT_IEEE_FLOAT = 0x0003; # IEEE float (32/64 bit) |
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50 FORMAT_ALAW = 0x0006; # 8-bit ITU-T G.711 A-law (not yet supported) |
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51 FORMAT_MULAW = 0x0007; # 8-bit ITU-T G.711 ยต-law (not yet supported) |
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52 FORMAT_IMA_ADPCM = 0x0011; # IMA/ADPCM 4:1 compression (not yet supported) |
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53 BYTEORDER = "ieee-le"; |
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54 |
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55 if (nargin < 1 || nargin > 2) |
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56 usage ("wavread (filename, param)"); |
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57 endif |
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58 |
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59 # open file for binary reading |
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60 |
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61 if (! ischar (filename)) |
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62 error ("wavwrite: expecting filename to be a character string"); |
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63 endif |
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64 |
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65 [fid, msg] = fopen (filename, "rb"); |
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66 if (fid < 0) |
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67 error ("wavread: %s", msg) |
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68 endif |
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69 |
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70 ## check for RIFF/WAVE header |
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71 ck_id = char (fread (fid, 4))'; |
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72 fseek (fid, 4, SEEK_CUR); |
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73 wave_id = char (fread (fid, 4))'; |
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74 if (ck_id != "RIFF" || wave_id != "WAVE") |
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75 fclose (fid); |
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76 error ("wavread: file contains no RIFF/WAVE signature"); |
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77 endif |
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78 |
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79 ## find format chunk within the next 256 (4*64) bytes |
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80 i = 1; |
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81 while (true) |
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82 if (char (fread (fid, 4))' == "fmt "); |
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83 break; |
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84 endif |
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85 if (i++ == 64) |
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86 fclose (fid); |
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87 error ("wavread: file contains no format chunk"); |
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88 endif |
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89 endwhile |
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90 |
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91 ## format chunk size |
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92 ck_size = fread (fid, 1, "ulong", 0, BYTEORDER); |
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93 |
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94 ## sample format code |
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95 format_tag = fread (fid, 1, "short", 0, BYTEORDER); |
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96 if (format_tag != FORMAT_PCM && format_tag != FORMAT_IEEE_FLOAT) |
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97 fclose (fid); |
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98 error ("wavread: sample format %#x is not supported", format_tag); |
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99 endif |
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100 |
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101 ## number of interleaved channels |
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102 channels = fread (fid, 1, "short", 0, BYTEORDER); |
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103 |
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104 ## sample rate |
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105 samples_per_sec = fread (fid, 1, "ulong", 0, BYTEORDER); |
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106 |
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107 ## bits per sample |
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108 fseek (fid, 6, SEEK_CUR); |
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109 bits_per_sample = fread (fid, 1, "short", 0, BYTEORDER); |
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110 |
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111 ## ignore the rest of the chunk |
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112 fseek (fid, ck_size-16, SEEK_CUR); |
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113 |
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114 ## find data chunk |
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115 i = 1; |
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116 while (true) |
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117 if (char (fread (fid, 4))' == "data") |
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118 break; |
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119 endif |
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120 if (i++ == 64) |
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121 fclose (fid); |
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122 error ("wavread: file contains no data chunk"); |
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123 endif |
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124 end |
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125 |
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126 ## data chunk size |
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127 ck_size = fread (fid, 1, "ulong", 0, BYTEORDER); |
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128 |
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129 ## determine sample data type |
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130 if (format_tag == FORMAT_PCM) |
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131 switch bits_per_sample |
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132 case 8 |
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133 format = "int8"; |
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134 case 16 |
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135 format = "int16"; |
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136 case 32 |
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137 format = "int32"; |
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138 otherwise |
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139 fclose (fid); |
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140 error ("wavread: %d bits sample resolution is not supported with PCM", bits_per_sample); |
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141 endswitch |
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142 else |
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143 switch (bits_per_sample) |
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144 case 32 |
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145 format = "float32"; |
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146 case 64 |
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147 format = "float64"; |
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148 otherwise |
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149 fclose (fid); |
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150 error ("wavread: %d bits sample resolution is not supported with IEEE float", bits_per_sample); |
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151 endswitch |
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152 endif |
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153 |
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154 ## parse arguments |
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155 if (nargin == 1) |
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156 length = inf; |
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157 else |
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158 if (size (param, 2) == 1) |
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159 ## number of samples is given |
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160 length = param * channels; |
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161 elseif (size (param, 2) == 2) |
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162 ## sample range is given |
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163 if (fseek (fid, param(1) * channels * (bits_per_sample/8), SEEK_CUR) < 0) |
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164 warning ("wavread: seeking failed"); |
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165 endif |
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166 length = (param(2)-param(1)) * channels; |
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167 elseif (size (param, 2) == 4 && char (param) == "size") |
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168 ## size of the file is requested |
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169 fclose (fid); |
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170 y = [ck_size/channels/bits_per_sample/8, channels]; |
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171 return |
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172 else |
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173 fclose (fid); |
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174 error ("wavread: invalid argument 2"); |
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175 endif |
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176 endif |
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177 |
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178 ## read samples |
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179 [yi, n] = fread (fid, length, format, 0, BYTEORDER); |
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180 |
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181 fclose (fid); |
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182 |
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183 if (format_tag == FORMAT_PCM) |
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184 ## normalize samples |
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185 switch (bits_per_sample) |
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186 case 8 |
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187 yi = (yi - 127)/127; # 8-bit samples are unsigned |
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188 case {16, 32} |
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189 yi = yi/((2 ** bits_per_sample) / 2 - 1); |
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190 endswitch |
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191 endif |
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192 |
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193 ## deinterleave |
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194 ## y = []; |
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195 ## for i = 1:channels |
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196 ## y = [y, yi(i:channels:n)]; |
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197 ## endfor |
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198 |
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199 nr = numel (yi) / channels; |
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200 y = reshape (yi, channels, nr)'; |
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201 |
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202 endfunction |
