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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 3 of the License, or (at |
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8 ## your option) 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {@var{y} =} wavread (@var{filename}) |
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21 ## Load the RIFF/WAVE sound file @var{filename}, and return the samples |
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22 ## in vector @var{y}. If the file contains multichannel data, then |
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23 ## @var{y} is a matrix with the channels represented as columns. |
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24 ## |
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25 ## @deftypefnx {Function File} {[@var{y}, @var{Fs}, @var{bits}] =} wavread (@var{filename}) |
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26 ## Additionally return the sample rate (@var{fs}) in Hz and the number of bits |
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27 ## per sample (@var{bits}). |
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28 ## |
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29 ## @deftypefnx {Function File} {[@dots{}] =} wavread (@var{filename}, @var{n}) |
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30 ## Read only the first @var{n} samples from each channel. |
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31 ## |
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32 ## @deftypefnx {Function File} {[@dots{}] =} wavread (@var{filename},[@var{n1} @var{n2}]) |
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33 ## Read only samples @var{n1} through @var{n2} from each channel. |
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34 ## |
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35 ## @deftypefnx {Function File} {[@var{samples}, @var{channels}] =} wavread (@var{filename}, "size") |
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36 ## Return the number of samples (@var{n}) and channels (@var{ch}) |
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37 ## instead of the audio data. |
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38 ## @seealso{wavwrite} |
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39 ## @end deftypefn |
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40 |
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41 ## Author: Michael Zeising <michael.zeising@stud.uni-erlangen.de> |
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42 ## Created: 06 December 2005 |
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43 |
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44 function [y, samples_per_sec, bits_per_sample] = wavread (filename, param) |
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45 |
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46 FORMAT_PCM = 0x0001; # PCM (8/16/32 bit) |
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47 FORMAT_IEEE_FLOAT = 0x0003; # IEEE float (32/64 bit) |
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48 BYTEORDER = "ieee-le"; |
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49 |
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50 if (nargin < 1 || nargin > 2) |
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51 print_usage (); |
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52 endif |
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53 |
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54 if (! ischar (filename)) |
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55 error ("wavwrite: expecting filename to be a character string"); |
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56 endif |
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57 |
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58 # open file for binary reading |
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59 [fid, msg] = fopen (filename, "rb"); |
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60 if (fid < 0) |
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61 error ("wavread: %s", msg); |
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62 endif |
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63 |
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64 ## check for RIFF/WAVE header |
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65 ck_id = char (fread (fid, 4))'; |
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66 fseek (fid, 4, SEEK_CUR); |
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67 wave_id = char (fread (fid, 4))'; |
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68 if (ck_id != "RIFF" || wave_id != "WAVE") |
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69 fclose (fid); |
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70 error ("wavread: file contains no RIFF/WAVE signature"); |
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71 endif |
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72 |
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73 ## find format chunk within the next 256 (4*64) bytes |
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74 i = 1; |
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75 while (true) |
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76 if (char (fread (fid, 4))' == "fmt "); |
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77 break; |
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78 endif |
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79 if (i++ == 64) |
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80 fclose (fid); |
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81 error ("wavread: file contains no format chunk"); |
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82 endif |
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83 endwhile |
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84 |
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85 ## format chunk size |
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86 ck_size = fread (fid, 1, "uint32", 0, BYTEORDER); |
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87 |
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88 ## sample format code |
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89 format_tag = fread (fid, 1, "uint16", 0, BYTEORDER); |
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90 if (format_tag != FORMAT_PCM && format_tag != FORMAT_IEEE_FLOAT) |
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91 fclose (fid); |
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92 error ("wavread: sample format %#x is not supported", format_tag); |
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93 endif |
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94 |
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95 ## number of interleaved channels |
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96 channels = fread (fid, 1, "uint16", 0, BYTEORDER); |
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97 |
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98 ## sample rate |
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99 samples_per_sec = fread (fid, 1, "uint32", 0, BYTEORDER); |
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100 |
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101 ## bits per sample |
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102 fseek (fid, 6, SEEK_CUR); |
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103 bits_per_sample = fread (fid, 1, "uint16", 0, BYTEORDER); |
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104 |
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105 ## ignore the rest of the chunk |
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106 fseek (fid, ck_size-16, SEEK_CUR); |
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107 |
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108 ## find data chunk |
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109 i = 1; |
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110 while (true) |
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111 if (char (fread (fid, 4))' == "data") |
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112 break; |
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113 endif |
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114 if (i++ == 64) |
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115 fclose (fid); |
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116 error ("wavread: file contains no data chunk"); |
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117 endif |
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118 end |
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119 |
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120 ## data chunk size |
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121 ck_size = fread (fid, 1, "uint32", 0, BYTEORDER); |
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122 |
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123 ## determine sample data type |
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124 if (format_tag == FORMAT_PCM) |
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125 switch (bits_per_sample) |
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126 case 8 |
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127 format = "uint8"; |
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128 case 16 |
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129 format = "int16"; |
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130 case 24 |
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131 format = "uint8"; |
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132 case 32 |
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133 format = "int32"; |
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134 otherwise |
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135 fclose (fid); |
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136 error ("wavread: %d bits sample resolution is not supported with PCM", |
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137 bits_per_sample); |
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138 endswitch |
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139 else |
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140 switch (bits_per_sample) |
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141 case 32 |
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142 format = "float32"; |
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143 case 64 |
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144 format = "float64"; |
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145 otherwise |
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146 fclose (fid); |
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147 error ("wavread: %d bits sample resolution is not supported with IEEE float", |
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148 bits_per_sample); |
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149 endswitch |
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150 endif |
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151 |
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152 ## parse arguments |
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153 if (nargin == 1) |
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154 length = inf; |
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155 else |
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156 if (size (param, 2) == 1) |
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157 ## number of samples is given |
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158 length = param * channels; |
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159 elseif (size (param, 2) == 2) |
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160 ## sample range is given |
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161 if (fseek (fid, (param(1)-1) * channels * (bits_per_sample/8), SEEK_CUR) < 0) |
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162 warning ("wavread: seeking failed"); |
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163 endif |
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164 length = (param(2)-param(1)+1) * channels; |
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165 elseif (size (param, 2) == 4 && char (param) == "size") |
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166 ## size of the file is requested |
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167 fclose (fid); |
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168 y = [ck_size/channels/(bits_per_sample/8), channels]; |
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169 return |
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170 else |
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171 fclose (fid); |
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172 error ("wavread: invalid argument 2"); |
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173 endif |
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174 endif |
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175 |
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176 ## read samples and close file |
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177 if (bits_per_sample == 24) |
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178 length *= 3; |
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179 endif |
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180 [yi, n] = fread (fid, length, format, 0, BYTEORDER); |
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181 fclose (fid); |
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182 |
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183 ## check data |
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184 if (mod (numel (yi), channels) != 0) |
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185 error ("wavread: data in %s doesn't match the number of channels", |
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186 filename); |
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187 endif |
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188 |
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189 if (bits_per_sample == 24) |
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190 yi = reshape (yi, 3, rows(yi)/3)'; |
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191 yi(yi(:,3) >= 128, 3) -= 256; |
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192 yi = yi * [1; 256; 65536]; |
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193 end |
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194 if (format_tag == FORMAT_PCM) |
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195 ## normalize samples |
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196 switch (bits_per_sample) |
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197 case 8 |
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198 yi = (yi - 127.5)/127.5; |
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199 case 16 |
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200 yi /= 32768; |
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201 case 24 |
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202 yi /= 8388608; |
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203 case 32 |
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204 yi /= 2147483648; |
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205 endswitch |
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206 endif |
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207 |
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208 ## deinterleave |
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209 nr = numel (yi) / channels; |
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210 y = reshape (yi, channels, nr)'; |
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211 |
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212 endfunction |
