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    1.3.1 • Public • Published


    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.

    MacOS (via homebrew)

    $ brew install portaudio fftw

    Ubuntu (with apt-get)

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


    ...not supported yet.


    $ npm i soundengine

    Basic usage example

    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
    // 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
        // Playback of the recording
    }, 5000)
    // Let the programm run forever



    To list the available devices

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

    Device properties

    Engine options

    Property Type Description
    id number The device id to use in the engine options.
    name string The device name.
    defaultSampleRate number The default sample rate of the device.
    maxInputChannels number The maximum supported input channels for this device.
    maxOutputChannels number The maximum supported output channels for this device.
    defaultLowInputLatency number See PortAudio docs
    defaultLowOutputLatency number See PortAudio docs
    defaultHighInputLatency number See PortAudio docs
    defaultHighOutputLatency number See PortAudio docs

    Engine methods

    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.

    (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.

    Engine options

    Option Type Default Description
    sampleRate number 44100 Samples per second for each channel.
    bufferSize number 1024 The count of samples for each processing iteration.
    inputChannels number 1 The number of input channels.
    outputChannels number 1 The number of output channels (should equal inputChannels).
    inputDevice number default input device The id of the input device to use or -1 for a output only stream.
    outputDevice number default output device The id of the output device to use or -1 for a input only stream.
    inputLatency number default high input latency See PortAudio docs
    outputLatency number default high output latency See PortAudio docs

    Beep options

    Option Type Default Description
    duration number 200 The duration of the applied beep in ms.
    frequency number 700 The frequency of the beep (sine wave).
    level number 1.0 The volume of the beep (between 0..1).

    Engine events

    EventName Signature Description
    data (inputBuffer: number[]): number[] Will be called when a new inputBuffer is available to be processed and returned. Note: If the processing function takes to long to process the buffer you might experience dropouts.
    info ({min: number[], max: number[]}) This event gets fired with messurements of the inputBuffer such as peaks (min) for every channel.
    playback_started Gets fired when playback started.
    playback_stopped Gets fired when playback stopped.
    playback_paused Gets fired when playback paused.
    playback_progress (progress: number) Gets fired when playback progressed with the relative progress.
    playback_finished Gets fired when playback reached the end of the recording or loaded wave.
    recording_loaded Gets fired when the loadRecording loaded a file successfully.
    recording_started Gets fired when recording started.
    recording_stopped Gets fired when recording stopped.
    recording_progress Gets fired when recording progressed.
    recording_saved Gets fired when the recording was saved with saveRecording.
    recording_deleted Gets fired when the recording in memory was deleted.
    beep_started Gets fired when the beep method started apply a beep to the output.
    beep_stopped Gets fired when the beep method stopped apply a beep to the output.


    • Implement fft stuff


    npm i soundengine

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