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apeheader.pm
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apeheader.pm
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# Copyright (c) Quentin Sculo <squentin@free.fr>
# Copyright (c) Alexandr Savca <alexandr.savca89@gmail.com>
#
# This file is part of jukebox.
#
# jukebox is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3, as
# published by the Free Software Foundation
package Tag::APEfile;
use strict;
use warnings;
our @ISA = ('Tag::MP3');
my %compression;
INIT {
%compression = (
1000 => 'Fast',
2000 => 'Normal',
3000 => 'High',
4000 => 'Extra High',
5000 => 'Insane',
);
}
sub new {
my ($class, $file, $findlength) = @_;
my $self = bless {}, $class;
local $_;
# check that the file exists
unless (-e $file) {
warn "File '$file' does not exist.\n";
return undef;
}
$self->{filename} = $file;
$self->_open or return undef;
$self->_FindTags;
$self->_ReadHeader;
return undef unless $self->{info};
$self->_close;
return $self;
}
sub _ReadHeader {
my $self = $_[0];
my $fh = $self->{fileHandle};
my $offset = $self->{startaudio};
seek $fh, $offset, 0;
my $buf;
return unless read($fh, $buf, 32) == 32;
my ($sig, $v, $desc_size) = unpack 'a4vx2v', $buf;
return unless $sig eq 'MAC ';
my ($compression, $blocksperframe, $finalsblocks, $nbframes,
$channels, $freq);
if ($v < 3980) {
# old header
($compression, $channels, $freq, $nbframes, $finalsblocks) =
unpack 'x6vx2vVx8VV', $buf;
if ($v >= 3950) {
$blocksperframe = 73728 * 4;
}
elsif ($v >= 3900 || ($v >= 3800 && $compression == 4000)) {
$blocksperframe = 73728;
}
else {
$blocksperframe = 9216;
}
}
else {
seek $fh, $desc_size - 32, 1;
return unless read($fh, $buf, 24) == 24;
($compression, $blocksperframe, $finalsblocks, $nbframes,
$channels, $freq) = unpack 'vx2VVVx2vV', $buf;
}
my $bitrate = my $seconds = 0;
my $blocks = ($nbframes - 1) * $blocksperframe + $finalsblocks;
if ($blocks & $freq) {
$seconds = $blocks / $freq;
$bitrate =
($self->{endaudio} - $self->{startaudio}) * 8 / $seconds;
}
my %info = (
version => $v / 1000,
channels => $channels,
frames => $nbframes,
rate => $freq,
seconds => $seconds,
bitrate => $bitrate,
compression => $compression{$compression} || $compression,
);
#warn "$_=$info{$_}\n" for keys %info;
$self->{info} = \%info;
}
1;
# vim:sw=4:ts=4:sts=4:et:cc=72:tw=70
# End of file.