A C++ addon for node.js that allows interacting with soundcards to e.g. play, record or process live microphone samples and send them back to the speakers. The module uses PortAudio to interact with the different host apis.

Soundengine requires the shared portaudio library.

$ brew install portaudio fftw

$ sudo apt-get install libasound-dev libportaudio2 portaudio19-dev libfftw3-3 libfftw3-dev libfftw3-double3

...not supported yet.

$ npm i soundengine

const soundengine = require('soundengine')

// Start live transmission from the default input device to the default output device at 22kHz
var engine = new soundengine.engine({sampleRate: 22050})

// Start recording
engine.startRecording()

// Apply a beep to the output when recording has stopped
engine.on('recording_stopped', () => {
    engine.beep({frequency: 300})
})

// Stop recording after 5 seconds
setTimeout(() => {
    // Stop the recording
    engine.stopRecording()

    // Playback of the recording
    engine.startPlayback()
}, 5000)

// Let the programm run forever
process.stdin.resume()

To list the available devices

const soundengine = require('soundengine')
var devices = soundengine.getDevices()

The engine class actually has almost all the methods of a nodejs EventEmitter to interact with the upcomming events. Furthermore these methods exist:

• loadRecording(file: string) - Loads a wave file that is then playable with startPlayback(). ⁽¹⁾
• startPlayback() - Starts playback of the last recording or loaded file.
• stopPlayback() - Stops playback.
• pausePlayback() - Pauses playback.
• isPlaying(): boolean - Returns if playback is active.
• startRecording() - Starts recording.
• stopRecording() - Stops recording.
• deleteRecording() - Deletes the recording that is currently held in memory.
• saveRecording(file: string) - Saves the recording to a wave file. ⁽²⁾
• isRecording(): boolean - Returns if recording is active.
• getRecordingSamples(): number - Return the number of total samples.
• getPlaybackPosition(): number - Returns the current sample index of the playback.
• getRecordingSampleAt(index: number): number - Returns a specific sample (between -1..1) at index.
• getPlaybackProgress(): number - Returns the relative playback progress (between 0..1).
• setPlaybackProgress(progress: number) - Sets the relative playback progress (between 0..1).
• beep(options?: beepOptions) - Applies a beep to the output.
• getVolume(): number - Returns the volume (between 0..1).
• setVolume(volume: number) - Sets the volume (between 0..1).
• getMute(): boolean - Returns if the output is muted or not.
• setMute(mute?: boolean) - Mutes or unmutes the output.
• getOptions(): engineOptions - Returns the current engine options.
• setOptions(options?: engineOptions) - Sets the engine options.
• synchronize() - Clears the internal buffer queues. If there for example is a large delay between the input and the output after initializing a new engine, calling synchronize could potentially minimize this delay.

Notes:
(1) Currently only 32bit floating point waves with the same samplerate of the current engine can be loaded (and the header will not be checked).
(2) The wave files are 32bit floating point.

• Implement fft stuff