Audio::Wav(3) Modules for reading & writing Microsoft WAV files.

SYNOPSIS


# copying a file and adding some cue points to the output file
use Audio::Wav;
my $wav = new Audio::Wav;
my $read = $wav -> read( 'input.wav' );
my $write = $wav -> write( 'output.wav', $read -> details() );
print "input is ", $read -> length_seconds(), " seconds long\n";
$write -> set_info( 'software' => 'Audio::Wav' );
my $data;
#read 512 bytes
while ( defined( $data = $read -> read_raw( 512 ) ) ) {
$write -> write_raw( $data );
}
my $length = $read -> length_samples();
my( $third, $half, $twothirds ) = map int( $length / $_ ), ( 3, 2, 1.5 );
my %samp_loop = (
'start' => $third,
'end' => $twothirds,
);
$write -> add_sampler_loop( %samp_loop );
$write -> add_cue( $half, "cue label 1", "cue note 1" );
$write -> finish();
# splitting a multi-channel file to separate mono files (slowly!);
use Audio::Wav;
my $read = $wav -> read( '4ch.wav' );
my $details = $read -> details();
my %out_details = map { $_ => $details -> {$_} } 'bits_sample', 'sample_rate';
$out_details{channels} = 1;
my @out_files;
my $in_channels = $details -> {channels};
foreach my $channel ( 1 .. $in_channels ) {
push @out_files, $wav -> write( 'multi_' . $channel . '.wav', \%out_details );
}
while ( 1 ) {
my @channels = $read -> read();
last unless @channels;
foreach my $channel_id ( 0 .. $#channels ) {
$out_files[$channel_id] -> write( $channels[$channel_id] );
}
}
# not entirely necessary as finish is done in DESTROY now (if the file hasn't been finished already).
foreach my $write ( @out_files ) {
$write -> finish();
}

NOTES

All sample positions are now in sample offsets (unless option '.01compatible' is true).

There is now *very* basic support for WAVEFORMATEXTENSIBLE (in fact it only recognises that the file is in this format). The key 'wave-ex' is used in the detail hash to denote this format when reading or writing. I'd like to do more with this, but don't have any hardware or software to test these files, also don't really have any spare time to do the implementation at present.

One day I plan to learn enough C to do the sample reading/ writing in XS, but for the time being it's done using pack/ unpack in Perl and is slow. Working with the raw format doesn't suffer in this way.

It's likely that reading/ writing files with bit-depth greater than 16 won't work properly, I need to look at this at some point.

DESCRIPTION

These modules provide a method of reading & writing uncompressed Microsoft WAV files.

METHODS

new

Returns a blessed Audio::Wav object. All the parameters are optional and default to 0 

    my %options = (
        '.01compatible'   => 0,
        'oldcooledithack' => 0,
        'debug'           => 0,
    );
    my $wav = Audio::Wav -> new( %options );

write

Returns a blessed Audio::Wav::Write object. 

    my $details = {
        'bits_sample'   => 16,
        'sample_rate'   => 44100,
        'channels'      => 2,
    };
    my $write = $wav -> write( 'testout.wav', $details );
    my $write = Audio::Wav -> write( 'testout.wav', $details);
    my $write = Audio::Wav -> write( 'testout.wav', $details, %options );

where %options is in the form of arguments for Audio::Wav::Tools.

See Audio::Wav::Write for methods.

read

Returns a blessed Audio::Wav::Read object. 

    my $read = $wav -> read( 'testin.wav' );
    my $read = Audio::Wav -> read( 'testin.wav' );
    my $read = Audio::Wav -> read( 'testin.wav', %options );

where %options is in the form of arguments for Audio::Wav::Tools.

See Audio::Wav::Read for methods.

set_error_handler

Specifies a subroutine for catching errors. The subroutine should take a hash as input. The keys in the hash are 'filename', 'message' (error message), and 'warning'. If no error handler is set, die and warn will be used. 

    sub myErrorHandler {
        my( %parameters ) = @_;
        if ( $parameters{warning} ) {
            # This is a non-critical warning
            warn "Warning: $parameters{filename}: $parameters{message}\n";
        } else {
            # Critical error!
            die "ERROR: $parameters{filename}: $parameters{message}\n";
        }
    }
    $wav -> set_error_handler( \&myErrorHandler );

COPYRIGHT

    Copyright (c) 2007-2012 Brian Szymanski <[email protected]>
    Copyright (c) 1998-2006 Nick Peskett <[email protected]>
    Copyright (c) 2001 Kurt George Gjerde <[email protected]>

AUTHORS

    Nick Peskett (see http://www.peskett.co.uk/ for contact details).
    Brian Szymanski <[email protected]> (0.07-0.14)
    Wolfram humann (pureperl 24 and 32 bit read support in 0.09)
    Kurt George Gjerde <[email protected]>. (0.02-0.03)
    see also Changes file

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