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README file for Audio::Wav (0.06).
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Modules for reading & writing Microsoft WAV files.
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INSTALLATION
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tar zxvf Audio-Wav-0.06.tar.gz
cd Audio-Wav-0.06
perl Makefile.PL
make test
make install
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DOCUMENTATION
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Audio::Wav
Modules for reading & writing Microsoft WAV files.
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NAME
Audio::Wav - 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 seperate 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 neccessary 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 );
See Audio::Wav::Write for methods.
read
Returns a blessed Audio::Wav::Read object.
my $read = $wav -> read( 'testout.wav' );
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 );
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Audio::Wav::Read
Module for reading Microsoft WAV files.
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NAME
Audio::Wav::Read - Module for reading Microsoft WAV files.
SYNOPSIS
use Audio::Wav;
my $wav = new Audio::Wav;
my $read = $wav -> read( 'filename.wav' );
my $details = $read -> details();
DESCRIPTION
Reads Microsoft Wav files.
SEE ALSO
Audio::Wav
Audio::Wav::Write
NOTES
This module shouldn't be used directly, a blessed object can be returned
from Audio::Wav.
METHODS
file_name
Returns the file name.
my $file = $read -> file_name();
get_info
Returns information contained within the wav file.
my $info = $read -> get_info();
Returns a reference to a hash containing; (for example, a file marked up
for use in Audio::Mix)
{
'keywords' => 'bpm:126 key:a',
'name' => 'Mission Venice',
'artist' => 'Nightmares on Wax'
};
get_cues
Returns the cuepoints marked within the wav file.
my $cues = $read -> get_cues();
Returns a reference to a hash containing; (for example, a file marked up
for use in Audio::Mix) (position is sample position)
{
1 => {
label => 'sig',
position => 764343,
note => 'first'
},
2 => {
label => 'fade_in',
position => 1661774,
note => 'trig'
},
3 => {
label => 'sig',
position => 18033735,
note => 'last'
},
4 => {
label => 'fade_out',
position => 17145150,
note => 'trig'
},
5 => {
label => 'end',
position => 18271676
}
}
read_raw
Reads raw packed bytes from the current audio data position in the file.
my $data = $self -> read_raw( $byte_length );
read_raw_samples
Reads raw packed samples from the current audio data position in the
file.
my $data = $self -> read_raw_samples( $samples );
read
Returns the current audio data position sample across all channels.
my @channels = $self -> read();
Returns an array of unpacked samples. Each element is a channel i.e (
left, right ). The numbers will be in the range;
where $samp_max = ( 2 ** bits_per_sample ) / 2
-$samp_max to +$samp_max
position
Returns the current audio data position (as byte offset).
my $byte_offset = $read -> position();
position_samples
Returns the current audio data position (in samples).
my $samples = $read -> position_samples();
move_to
Moves the current audio data position to byte offset.
$read -> move_to( $byte_offset );
move_to_sample
Moves the current audio data position to sample offset.
$read -> move_to_sample( $sample_offset );
length
Returns the number of bytes of audio data in the file.
my $audio_bytes = $read -> length();
length_samples
Returns the number of samples of audio data in the file.
my $audio_samples = $read -> length_samples();
length_seconds
Returns the number of seconds of audio data in the file.
my $audio_seconds = $read -> length_seconds();
details
Returns a reference to a hash of lots of details about the file. Too
many to list here, try it with Data::Dumper.....
use Data::Dumper;
my $details = $read -> details();
print Data::Dumper->Dump([ $details ]);
reread_length
Rereads the length of the file in case it is being written to as we are
reading it.
my $new_data_length = $read -> reread_length();
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Audio::Wav::Write
Module for writing Microsoft WAV files.
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NAME
Audio::Wav::Write - Module for writing Microsoft WAV files.
SYNOPSIS
use Audio::Wav;
my $wav = new Audio::Wav;
my $sample_rate = 44100;
my $bits_sample = 16;
my $details = {
'bits_sample' => $bits_sample,
'sample_rate' => $sample_rate,
'channels' => 1,
# if you'd like this module not to use a write cache, uncomment the next line
#'no_cache' => 1,
};
my $write = $wav -> write( 'testout.wav', $details );
&add_sine( 200, 1 );
sub add_sine {
my $hz = shift;
my $length = shift;
my $pi = ( 22 / 7 ) * 2;
$length *= $sample_rate;
my $max_no = ( 2 ** $bits_sample ) / 2;
for my $pos ( 0 .. $length ) {
$time = $pos / $sample_rate;
$time *= $hz;
my $val = sin $pi * $time;
my $samp = $val * $max_no;
$write -> write( $samp );
}
}
$write -> finish();
DESCRIPTION
Currently only writes to a file.
SEE ALSO
Audio::Wav
Audio::Wav::Read
NOTES
This module shouldn't be used directly, a blessed object can be returned
from Audio::Wav.
METHODS
finish
Finishes off & closes the current wav file.
$write -> finish();
add_cue
Adds a cue point to the wav file. If $sample is undefined then the
position will be the current position (end of all data written so far).
# $byte_offset for 01 compatibility mode
$write -> add_cue( $sample, "label", "note" );
set_sampler_info
All parameters are optional.
my %info = (
'midi_pitch_fraction' => 0,
'smpte_format' => 0,
'smpte_offset' => 0,
'product' => 0,
'sample_period' => 0,
'manufacturer' => 0,
'sample_data' => 0,
'midi_unity_note' => 65,
);
$write -> set_sampler_info( %info );
add_sampler_loop
All parameters are optional except start & end.
my $length = $read -> length_samples();
my( $third, $twothirds ) = map int( $length / $_ ), ( 3, 1.5 );
my %loop = (
'start' => $third,
'end' => $twothirds,
'fraction' => 0,
'type' => 0,
);
$write -> add_sampler_loop( %loop );
add_display
set_info
Sets information to be contained in the wav file.
$write -> set_info( 'artist' => 'Nightmares on Wax', 'name' => 'Mission Venice' );
file_name
Returns the current filename.
my $file = $write -> file_name();
write
Adds a sample to the current file.
$write -> write( @sample_channels );
Each element in @sample_channels should be in the range of;
where $samp_max = ( 2 ** bits_per_sample ) / 2
-$samp_max to +$samp_max
write_raw
Adds some pre-packed data to the current file.
$write -> write_raw( $data, $data_length );
Where;
$data is the packed data
$data_length (optional) is the length in bytes of the data
write_raw_samples
Adds some pre-packed data to the current file, returns number of samples
written.
$write -> write_raw_samples( $data, $data_length );
Where;
$data is the packed data
$data_length (optional) is the length in bytes of the data
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AUTHORS
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Nick Peskett (see http://www.peskett.co.uk/ for contact details).
Kurt George Gjerde <kurt.gjerde@media.uib.no>. (0.02-0.03)
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END
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