go-sound

go-sound is a go library for dealing with sound waves. At the fundamental level, the library models each sound as a channel of [-1, 1] samples that represent the Compression Wave that comprises the sound.
To see it it action, check out demo.go or the examples provided by each file in the sounds package.

A tutorial explaining the basics behind sound wave modelling in code, and how it is implemented in go-sound, is available on my blog: http://padsterprogramming.blogspot.ch/2015/11/sounds-good-part-1.html

Features :

• A Sound interface, with a BaseSound implementation that makes it simpler to write your own.
• Sound Math (play notes together to make chords, or in serial to form a melody, ...)
• Utilities for dealing with sounds (repeat sounds, generate from text, ...)
• Implementations for various inputs (silence, sinusoidal wave, .wav file, ...)
• Implementations for various outputs (play via pulse audio, draw to screen, .wav file, ...)
• Realtime input (via MIDI) - with delay though.
• Sound -> Spectrogram -> Sound conversion using a Constant Q transform

In progress:

• MashApp, a golang server and polymer web app for manipulating sounds using the library.

Future plans:

• Inputs and Outputs integrating with Jack Audio
• Realtime input from microphone, more efficient from MIDI
• Effects algorithms (digitial processing like reverb, bandpass ...)

Notes:

This library requires pulse audio installed to play the sounds, libflac for reading/writing flac files, and OpenGL 3.3 / GLFW 3.1 for rendering a soundwave to screen.

Some planned additions are included above, and include effects like those available in Audacity (e.g. rewriting Nyquist, LADSPA plugins in Go), or ones explained here or here. Additionally, some more complex instrument synthesizers could be added, and contributions are welcome.

The example piano .wav C note came from: http://freewavesamples.com/ensoniq-sq-1-dyno-keys-c4

Frequencies of notes are all obtained from: http://www.phy.mtu.edu/~suits/notefreqs.html

For MIDI input, a number of things are required for portmidi:

• Instructions to test the midi input device: https://wiki.archlinux.org/index.php/USB_MIDI_keyboards
• Instructions to set linux up for realtime processing: http://tedfelix.com/linux/linux-midi.html
• ALSA dev library required (libasound2-dev)
• I needed to manually install portmidi: http://sourceforge.net/p/portmedia/wiki/Installing_portmidi_on_Linux/
  • This also required removing the "WORKING_DIRECTORY pm_java)" in the ccmake configs
  • And to link against /usr/local/lib/libportmidi.so instead of /usr/lib/libporttime.so

Overall quite a pain and there's still a noticeable delay in the MIDI input, patches to reduce that are welcome!

Credit to cryptix, cocoonlife, moriyoshi and rakyll for their wavFile, pulseAudio and portmidi implementations respectively, used by go-sound.