238 lines
8.5 KiB
Perl
238 lines
8.5 KiB
Perl
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#------------------------------------------------------------------------------
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# File: Ogg.pm
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#
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# Description: Read Ogg meta information
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#
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# Revisions: 2011/07/13 - P. Harvey Created (split from Vorbis.pm)
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#
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# References: 1) http://www.xiph.org/vorbis/doc/
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# 2) http://flac.sourceforge.net/ogg_mapping.html
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# 3) http://www.theora.org/doc/Theora.pdf
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#------------------------------------------------------------------------------
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package Image::ExifTool::Ogg;
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use strict;
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use vars qw($VERSION);
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use Image::ExifTool qw(:DataAccess :Utils);
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$VERSION = '1.01';
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my $MAX_PACKETS = 2; # maximum packets to scan from each stream at start of file
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# Information types recognizedi in Ogg files
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%Image::ExifTool::Ogg::Main = (
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NOTES => q{
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ExifTool extracts the following types of information from Ogg files. See
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L<http://www.xiph.org/vorbis/doc/> for the Ogg specification.
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},
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# (these are for documentation purposes only, and aren't used by the code below)
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vorbis => { SubDirectory => { TagTable => 'Image::ExifTool::Vorbis::Main' } },
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theora => { SubDirectory => { TagTable => 'Image::ExifTool::Theora::Main' } },
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FLAC => { SubDirectory => { TagTable => 'Image::ExifTool::FLAC::Main' } },
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ID3 => { SubDirectory => { TagTable => 'Image::ExifTool::ID3::Main' } },
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);
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#------------------------------------------------------------------------------
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# Process Ogg packet
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# Inputs: 0) ExifTool object ref, 1) data ref
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# Returns: 1 on success
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sub ProcessPacket($$)
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{
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my ($et, $dataPt) = @_;
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my $rtnVal = 0;
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if ($$dataPt =~ /^(.)(vorbis|theora)/s) {
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my ($tag, $type) = (ord($1), ucfirst($2));
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# this is an OGV file if it contains Theora video
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$et->OverrideFileType('OGV') if $type eq 'Theora' and $$et{FILE_TYPE} eq 'OGG';
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my $tagTablePtr = GetTagTable("Image::ExifTool::${type}::Main");
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my $tagInfo = $et->GetTagInfo($tagTablePtr, $tag);
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return 0 unless $tagInfo and $$tagInfo{SubDirectory};
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my $subdir = $$tagInfo{SubDirectory};
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my %dirInfo = (
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DataPt => $dataPt,
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DirName => $$tagInfo{Name},
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DirStart => 7,
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);
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my $table = GetTagTable($$subdir{TagTable});
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# set group1 so Theoris comments can be distinguised from Vorbis comments
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$$et{SET_GROUP1} = $type if $type eq 'Theora';
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SetByteOrder($$subdir{ByteOrder}) if $$subdir{ByteOrder};
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$rtnVal = $et->ProcessDirectory(\%dirInfo, $table);
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SetByteOrder('II');
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delete $$et{SET_GROUP1};
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}
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return $rtnVal;
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}
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#------------------------------------------------------------------------------
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# Extract information from an Ogg file
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# Inputs: 0) ExifTool object reference, 1) dirInfo reference
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# Returns: 1 on success, 0 if this wasn't a valid Ogg file
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sub ProcessOGG($$)
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{
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my ($et, $dirInfo) = @_;
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# must first check for leading/trailing ID3 information
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unless ($$et{DoneID3}) {
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require Image::ExifTool::ID3;
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Image::ExifTool::ID3::ProcessID3($et, $dirInfo) and return 1;
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}
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my $raf = $$dirInfo{RAF};
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my $verbose = $et->Options('Verbose');
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my $out = $et->Options('TextOut');
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my ($success, $page, $packets, $streams, $stream) = (0,0,0,0,'');
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my ($buff, $flag, %val, $numFlac, %streamPage);
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for (;;) {
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# must read ahead to next page to see if it is a continuation
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# (this code would be a lot simpler if the continuation flag
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# was on the leading instead of the trailing page!)
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if ($raf and $raf->Read($buff, 28) == 28) {
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# validate magic number
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unless ($buff =~ /^OggS/) {
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$success and $et->Warn('Lost synchronization');
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last;
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}
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unless ($success) {
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# set file type and initialize on first page
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$success = 1;
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$et->SetFileType();
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SetByteOrder('II');
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}
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$flag = Get8u(\$buff, 5); # page flag
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$stream = Get32u(\$buff, 14); # stream serial number
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if ($flag & 0x02) {
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++$streams; # count start-of-stream pages
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$streamPage{$stream} = $page = 0;
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} else {
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$page = $streamPage{$stream};
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}
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++$packets unless $flag & 0x01; # keep track of packet count
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} else {
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# all done unless we have to process our last packet
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last unless %val;
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($stream) = sort keys %val; # take a stream
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$flag = 0; # no continuation
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undef $raf; # flag for done reading
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}
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if (defined $numFlac) {
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# stop to process FLAC headers if we hit the end of file
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last unless $raf;
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--$numFlac; # one less header packet to read
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} else {
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# can finally process previous packet from this stream
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# unless this is a continuation page
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if (defined $val{$stream} and not $flag & 0x01) {
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ProcessPacket($et, \$val{$stream});
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delete $val{$stream};
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# only read the first $MAX_PACKETS packets from each stream
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if ($packets > $MAX_PACKETS * $streams or not defined $raf) {
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last unless %val; # all done (success!)
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}
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}
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# stop processing Ogg if we have scanned enough packets
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last if $packets > $MAX_PACKETS * $streams and not %val;
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}
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# continue processing the current page
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my $pageNum = Get32u(\$buff, 18); # page sequence number
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my $nseg = Get8u(\$buff, 26); # number of segments
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# calculate total data length
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my $dataLen = Get8u(\$buff, 27);
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if ($nseg) {
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$raf->Read($buff, $nseg-1) == $nseg-1 or last;
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my @segs = unpack('C*', $buff);
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# could check that all these (but the last) are 255...
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foreach (@segs) { $dataLen += $_ }
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}
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if (defined $page) {
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if ($page == $pageNum) {
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$streamPage{$stream} = ++$page;
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} else {
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$et->Warn('Missing page(s) in Ogg file');
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undef $page;
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delete $streamPage{$stream};
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}
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}
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# read page data
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$raf->Read($buff, $dataLen) == $dataLen or last;
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if ($verbose > 1) {
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printf $out "Page %d, stream 0x%x, flag 0x%x (%d bytes)\n",
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$pageNum, $stream, $flag, $dataLen;
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$et->VerboseDump(\$buff, DataPos => $raf->Tell() - $dataLen);
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}
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if (defined $val{$stream}) {
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$val{$stream} .= $buff; # add this continuation page
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} elsif (not $flag & 0x01) { # ignore remaining pages of a continued packet
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# ignore the first page of any packet we aren't parsing
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if ($buff =~ /^(.)(vorbis|theora)/s) {
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$val{$stream} = $buff; # save this page
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} elsif ($buff =~ /^\x7fFLAC..(..)/s) {
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$numFlac = unpack('n',$1);
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$val{$stream} = substr($buff, 9);
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}
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}
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if (defined $numFlac) {
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# stop to process FLAC headers if we have them all
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last if $numFlac <= 0;
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} elsif (defined $val{$stream} and $flag & 0x04) {
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# process Ogg packet now if end-of-stream bit is set
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ProcessPacket($et, \$val{$stream});
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delete $val{$stream};
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}
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}
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if (defined $numFlac and defined $val{$stream}) {
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# process FLAC headers as if it was a complete FLAC file
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require Image::ExifTool::FLAC;
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my %dirInfo = ( RAF => new File::RandomAccess(\$val{$stream}) );
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Image::ExifTool::FLAC::ProcessFLAC($et, \%dirInfo);
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}
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return $success;
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}
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1; # end
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__END__
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=head1 NAME
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Image::ExifTool::Ogg - Read Ogg meta information
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=head1 SYNOPSIS
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This module is used by Image::ExifTool
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=head1 DESCRIPTION
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This module contains definitions required by Image::ExifTool to extract meta
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information from Ogg bitstream container files.
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=head1 AUTHOR
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Copyright 2003-2016, Phil Harvey (phil at owl.phy.queensu.ca)
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This library is free software; you can redistribute it and/or modify it
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under the same terms as Perl itself.
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=head1 REFERENCES
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=over 4
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=item L<http://www.xiph.org/vorbis/doc/>
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=item L<http://flac.sourceforge.net/ogg_mapping.html>
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=item L<http://www.theora.org/doc/Theora.pdf>
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=back
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=head1 SEE ALSO
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L<Image::ExifTool::TagNames/Ogg Tags>,
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L<Image::ExifTool(3pm)|Image::ExifTool>
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=cut
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