Audiogen

The audiogen package provides time domain audio processing tools using Python generators.

This makes some types of audio sample generation and processing pretty easy::

# mix 440 Hz and 445 Hz tones to get 5 Hz beating
beats = audiogen.util.mixer(
	(audiogen.tone(440), audiogen.tone(445)),
	[(constant(1), constant(1)),]
)

The actual samples won't be generated or stored in memory until they're actually consumed – for instance, when they're being written out to disk in a wave \file::

with open("output.wav", "wb") as f:
    audiogen.sampler.write_wav(f, beats)

Generators' at-consumption-time computation also allows creating infinitely long output, e.g. to stream to speakers rather than a file on disk::

audiogen.sampler.write_wav(sys.stdout, audiogen.tone(440))

Or just::

audiogen.sampler.play(audiogen.tone(440))

You can also use standard generator tools, e.g. the itertools module, to handle audio data::

beep_silence = itertools.chain(audiogen.beep(), audiogen.silence(0.5))
infinite_beeps = itertools.cycle(beep_silence)

audiogen.sampler.write_wav(sys.stdout, infinite_beeps)

Soundcard output

The easiest way to play directly to a soundcard output is to use the audiogen.sampler.play function, which will play your samples using PyAudio::

import audiogen
import itertools
import sys

audiogen.sampler.play(
    itertools.cycle(itertools.chain(audiogen.beep(), audiogen.silence(0.5)))
)

Alternatively, you could write your wave data to stdout, e.g. myaudio.py::

import audiogen
import itertools
import sys

audiogen.sampler.write_wav(
    sys.stdout,
    itertools.cycle(itertools.chain(audiogen.beep(), audiogen.silence(0.5)))
)

Then pipe to a command line audio player like Sox_::

python myaudio.py | play -t wav -

Installation

Install with::

$ pip install audiogen
$ pip install --allow-external PyAudio --allow-unverified PyAudio PyAudio

PyAudio is optional. If it's not installed, playing audio via the soundcard with audiogen.sampler.play() will not be available, but generating Wave files – including for piping to an external player, like sox – will work just fine.

Note that to install PyAudio on Mac OS X, you'll need to first install portaudio::

$ brew install portaudio

See also

Projects built with audiogen:

• koch <https://github.com/casebeer/koch>__, a Koch method Morse code trainer and audio generator
• afsk <https://github.com/casebeer/afsk>__, a ham radio APRS/Bell-202 audio frequency shift keying encoder

Contributing

Get the source and report any bugs on Github:

https://github.com/casebeer/audiogen

Version history

• 0.1.2 - Add band pass and band stop IIR filters; custom beep lengths from @jhobbs
• 0.1.1 - Fix multiplexing bug causing increase in pitch when using mixer() to produce more than one output channel
• 0.1.0 - Breaking changes: new arguments to tone(), play() blocks by default

.. _Sox: http://sox.sourceforge.net/