NAME
Audio::Analyzer::ToneDetect - Detect freq of tones in an audio file or
stream
SYNOPSIS
use Audio::Analyzer::ToneDetect;
my $tone_detect = Audio::Analyzer::ToneDetect->new( source => \*STDIN );
my $tone = $tone_detect->get_next_tone();
say "I heard $tone!";
DESCRIPTION
Consider this alpha software. It is still under fairly active
development and the interface may change in incompatible ways.
Audio::Analyzer::ToneDetect is a module for detecting single frequency
tones in an audio stream or file. It supports mono PCM data and defaults
to STDIN. For supporting other formats, eg MP3, you can pipe things
through sox.
USAGE
new (%opts)
Takes the following named parameters:
source \*FH or $path
The audio source. Only Mono PCM is supported. You can pass the path
to a WAV file or a file handle for an open file or stream. Defaults
to STDIN.
sample_rate 16000
Source sample rate, results will be orders of magnitude off if set
incorrectly. Defaults to 16000.
chunk_size 1024
Number of samples to analyze at once. Corresponds to dft_size in
Audio::Analyzer. Must be a power of 2. Defaults to 1024.
chunk_max 70
Maximum number of chunks to process before returning. Returns false
if it reaches this number of chunks without detecting a tone. With
default chunk_size and sample_rate, the default of 70 equates to
about 4.5 seconds of audio.
min_tone_length 0.5
Minimum durration of a tone, in seconds, before we consider it
detected. Due to sample rate, chunk size, and integer math, with
defaults this ends up being 0.448 seconds. The formula for actual
seconds is int( min_length * sample_rate / chunk_size ) * chunk_size
/ sample_rate. Default to 0.5
valid_tones undef, 'builtin', or ARRAYREF
A list of valid (expected) tones. If supplied, the closest expected
tone for a given detected tone is returned. Call get_next_tone() in
list context or supply the following call back if you want both
values. A value of 'builtin' uses a builtin list of valid classic
Motorola Minitor tones. Defaults to unset.
valid_error_cb
A callback that if provided and valid_tones is set will be called
just before get_next_tone or find_closest_valid returns. Arguments
are the closest valid tone, the actual detected tone, the diference
between the two in Hertz.
Example:
valid_error_cb => sub { printf "VF %s DF %s EF %.2f\n", @_; return }
Return value is expected to be one of three possibilities.
undef
Has no effect on program flow, if you don't want your call back
changing stuff make sure you have an explicit 'return' as the
last line.
Zero (the number)
A return value of 0 discards the tone and continues the
get_next_tone loop.
N Any other value replaces the valid detected tone with the return
value from the call back.
rejected_freqs undef or ARRAYREF
If specified, a reference to an array of frequencies that will be
ignored. e.g roger beeps, repeater beeps, etc. Note, if you use
valid tone detection, then this is the raw detected tone, not the
closest match. Defaults to empty list.
valid_tones
Returns the arraref of valid tones currently being used. Optionally
takes a reference to an array of new tones to use that will be copied to
replace the current valid list.
get_next_tone
Returns the next detected tone in the stream. Will return false if we go
through chunk_max without detecting a tone but the buffer will be
preserved between calls if the a tone begins just before hitting
chunk_max. If valid_tones was supplied, returns the result of passing
the tone to find_closest_valid(), following it's list vs scalar
semantics.
get_next_two_tones
Calls get next tone twice. Will return false if either tone returns
false.
find_closest_valid
In scalar context, returns the closest valid tone in valid_tones. In
list context returns the closest valid tone and the delta from detected
tone.
AUTHOR
Mike Greb <
[email protected]>
COPYRIGHT
Copyright 2013 - Mike Greb
LICENSE
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
SEE ALSO
Audio::Analyzer
Math::FFT
