1 | #------------------------------------------------------------------------------
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2 | # File: FLAC.pm
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3 | #
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4 | # Description: Read Free Lossless Audio Codec information
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5 | #
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6 | # Revisions: 11/13/2006 - P. Harvey Created
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7 | #
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8 | # References: 1) http://flac.sourceforge.net/
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9 | #------------------------------------------------------------------------------
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10 |
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11 | package Image::ExifTool::FLAC;
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12 |
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13 | use strict;
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14 | use vars qw($VERSION);
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15 | use Image::ExifTool qw(:DataAccess :Utils);
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16 |
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17 | $VERSION = '1.00';
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18 |
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19 | sub ProcessBitStream($$$);
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20 |
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21 | # FLAC metadata blocks
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22 | %Image::ExifTool::FLAC::Main = (
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23 | NOTES => q{
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24 | Free Lossless Audio Codec (FLAC) meta information. ExifTool also extracts
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25 | ID3 information from these files.
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26 | },
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27 | 0 => {
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28 | Name => 'StreamInfo',
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29 | SubDirectory => { TagTable => 'Image::ExifTool::FLAC::StreamInfo' },
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30 | },
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31 | 4 => {
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32 | Name => 'VorbisComment',
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33 | SubDirectory => { TagTable => 'Image::ExifTool::Vorbis::Comments' },
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34 | },
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35 | );
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36 |
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37 | %Image::ExifTool::FLAC::StreamInfo = (
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38 | PROCESS_PROC => \&ProcessBitStream,
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39 | NOTES => 'FLAC is big-endian, so bit 0 is the high-order bit in this table.',
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40 | GROUPS => { 2 => 'Audio' },
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41 | 'Bit000-015' => 'BlockSizeMin',
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42 | 'Bit016-031' => 'BlockSizeMax',
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43 | 'Bit032-055' => 'FrameSizeMin',
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44 | 'Bit056-079' => 'FrameSizeMax',
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45 | 'Bit080-099' => 'SampleRate',
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46 | 'Bit100-102' => {
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47 | Name => 'Channels',
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48 | ValueConv => '$val + 1',
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49 | },
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50 | 'Bit103-107' => {
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51 | Name => 'BitsPerSample',
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52 | ValueConv => '$val + 1',
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53 | },
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54 | 'Bit108-143' => 'TotalSamples',
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55 | );
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56 |
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57 | # FLAC composite tags
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58 | %Image::ExifTool::FLAC::Composite = (
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59 | Duration => {
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60 | Require => {
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61 | 0 => 'FLAC:SampleRate',
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62 | 1 => 'FLAC:Channels',
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63 | 2 => 'FLAC:TotalSamples',
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64 | },
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65 | ValueConv => '$val[0] and $val[1] and $val[2] ? $val[2] / ($val[0] * $val[1]) : undef',
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66 | PrintConv => 'sprintf("%.2fs",$val)',
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67 | },
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68 | );
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69 |
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70 | # add our composite tags
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71 | Image::ExifTool::AddCompositeTags('Image::ExifTool::FLAC');
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72 |
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73 |
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74 | #------------------------------------------------------------------------------
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75 | # Process information in a bit stream
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76 | # Inputs: 0) ExifTool object ref, 1) dirInfo ref, 2) tag table ref
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77 | # Notes: Byte order is used to determine the ordering of bits in the stream:
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78 | # 'MM' = bit 0 is most significant, 'II' = bit 0 is least significant
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79 | # - can handle arbitrarily wide values (ie. 8-byte or larger integers)
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80 | sub ProcessBitStream($$$)
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81 | {
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82 | my ($exifTool, $dirInfo, $tagTablePtr) = @_;
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83 | my $dataPt = $$dirInfo{DataPt};
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84 | my $dataPos = $$dirInfo{DataPos};
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85 | my $dirStart = $$dirInfo{DirStart} || 0;
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86 | my $dirLen = $$dirInfo{DirLen} || (length($$dataPt) - $dirStart);
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87 | my $verbose = $exifTool->Options('Verbose');
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88 | my $byteOrder = GetByteOrder();
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89 | my $tag;
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90 |
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91 | if ($verbose) {
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92 | $exifTool->VPrint(0, " + [BitStream directory, $dirLen bytes, '$byteOrder' order]\n");
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93 | }
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94 | foreach $tag (sort keys %$tagTablePtr) {
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95 | next unless $tag =~ /^Bit(\d+)-?(\d+)?/;
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96 | my ($b1, $b2) = ($1, $2 || $1); # start/end bit numbers in stream
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97 | my ($i1, $i2) = (int($b1 / 8), int($b2 / 8)); # start/end byte numbers
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98 | my ($f1, $f2) = ($b1 % 8, $b2 % 8); # start/end bit numbers within each byte
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99 | last if $i2 >= $dirLen;
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100 | my $val = 0;
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101 | my ($i, $mask, $extra);
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102 | $extra = ', Mask=0x' if $verbose and ($f1 != 0 or $f2 != 7);
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103 | if ($byteOrder eq 'MM') {
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104 | # loop from high byte to low byte
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105 | for ($i=$i1; $i<=$i2; ++$i) {
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106 | $mask = 0xff;
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107 | if ($i == $i1 and $f1) {
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108 | # mask off high bits in first word (0 is high bit)
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109 | foreach ((8-$f1) .. 7) { $mask ^= (1 << $_) }
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110 | }
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111 | if ($i == $i2 and $f2 < 7) {
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112 | # mask off low bits in last word (7 is low bit)
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113 | foreach (0 .. (6-$f2)) { $mask ^= (1 << $_) }
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114 | }
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115 | $val = $val * 256 + ($mask & Get8u($dataPt, $i + $dirStart));
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116 | $extra .= sprintf('%.2x', $mask) if $extra;
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117 | }
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118 | } else {
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119 | # (FLAC is big-endian, but support little-endian bit streams
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120 | # so this routine can be used by other modules)
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121 | # loop from high byte to low byte
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122 | for ($i=$i2; $i>=$i1; --$i) {
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123 | $mask = 0xff;
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124 | if ($i == $i1 and $f1) {
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125 | # mask off low bits in first word (0 is low bit)
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126 | foreach (0 .. ($f1-1)) { $mask ^= (1 << $_) }
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127 | }
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128 | if ($i == $i2 and $f2 < 7) {
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129 | # mask off high bits in last word (7 is high bit)
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130 | foreach (($f2+1) .. 7) { $mask ^= (1 << $_) }
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131 | }
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132 | $val = $val * 256 + ($mask & Get8u($dataPt, $i + $dirStart));
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133 | $extra .= sprintf('%.2x', $mask) if $extra;
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134 | }
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135 | }
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136 | # shift word down until low bit is in position 0
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137 | until ($mask & 0x01) {
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138 | $val /= 2;
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139 | $mask >>= 1;
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140 | }
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141 | $exifTool->HandleTag($tagTablePtr, $tag, $val,
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142 | DataPt => $dataPt,
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143 | DataPos => $dataPos,
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144 | Start => $dirStart + $i1,
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145 | Size => $i2 - $i1 + 1,
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146 | Extra => $extra,
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147 | );
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148 | }
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149 | return 1;
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150 | }
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151 |
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152 | #------------------------------------------------------------------------------
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153 | # Extract information from an Ogg FLAC file
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154 | # Inputs: 0) ExifTool object reference, 1) dirInfo reference
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155 | # Returns: 1 on success, 0 if this wasn't a valid Ogg FLAC file
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156 | sub ProcessFLAC($$)
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157 | {
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158 | my ($exifTool, $dirInfo) = @_;
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159 |
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160 | # must first check for leading/trailing ID3 information
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161 | unless ($exifTool->{DONE_ID3}) {
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162 | require Image::ExifTool::ID3;
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163 | Image::ExifTool::ID3::ProcessID3($exifTool, $dirInfo) and return 1;
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164 | }
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165 | my $raf = $$dirInfo{RAF};
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166 | my $verbose = $exifTool->Options('Verbose');
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167 | my $out = $exifTool->Options('TextOut');
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168 | my ($buff, $err);
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169 |
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170 | # check FLAC signature
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171 | $raf->Read($buff, 4) == 4 and $buff eq 'fLaC' or return 0;
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172 | $exifTool->SetFileType() unless $exifTool->{VALUE}->{FileType};
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173 | SetByteOrder('MM');
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174 | my $tagTablePtr = GetTagTable('Image::ExifTool::FLAC::Main');
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175 | for (;;) {
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176 | # read next metadata block header
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177 | $raf->Read($buff, 4) == 4 or last;
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178 | my $flag = unpack('C', $buff);
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179 | my $size = unpack('N', $buff) & 0x00ffffff;
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180 | $raf->Read($buff, $size) == $size or $err = 1, last;
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181 | my $last = $flag & 0x80; # last-metadata-block flag
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182 | my $tag = $flag & 0x7f; # tag bits
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183 | if ($verbose) {
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184 | print $out "FLAC metadata block, type $tag:\n";
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185 | $exifTool->VerboseDump(\$buff, DataPos => $raf->Tell() - $size);
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186 | }
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187 | $exifTool->HandleTag($tagTablePtr, $tag, undef,
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188 | DataPt => \$buff,
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189 | DataPos => $raf->Tell() - $size,
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190 | );
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191 | last if $last; # all done if is set
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192 | }
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193 | $err and $exifTool->Warn('Format error in FLAC file');
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194 | return 1;
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195 | }
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196 |
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197 | 1; # end
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198 |
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199 | __END__
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200 |
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201 | =head1 NAME
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202 |
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203 | Image::ExifTool::FLAC - Read Free Lossless Audio Codec information
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204 |
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205 | =head1 SYNOPSIS
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206 |
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207 | This module is used by Image::ExifTool
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208 |
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209 | =head1 DESCRIPTION
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210 |
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211 | This module contains definitions required by Image::ExifTool to extract meta
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212 | information from Free Lossless Audio Codec (FLAC) audio files.
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213 |
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214 | =head1 AUTHOR
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215 |
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216 | Copyright 2003-2007, Phil Harvey (phil at owl.phy.queensu.ca)
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217 |
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218 | This library is free software; you can redistribute it and/or modify it
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219 | under the same terms as Perl itself.
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220 |
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221 | =head1 REFERENCES
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222 |
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223 | =over 4
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224 |
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225 | =item L<http://flac.sourceforge.net/>
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226 |
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227 | =back
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228 |
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229 | =head1 SEE ALSO
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230 |
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231 | L<Image::ExifTool::TagNames/FLAC Tags>,
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232 | L<Image::ExifTool(3pm)|Image::ExifTool>
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233 |
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234 | =cut
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235 |
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