soundengine

# Soundengine 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](http://portaudio.com) to interact with the different host apis. ## Prerequisites Soundengine requires the shared portaudio library. ### MacOS (via homebrew) ```sh $ brew install portaudio fftw ``` ### Ubuntu (with apt-get) ```sh $ sudo apt-get install libasound-dev libportaudio2 portaudio19-dev libfftw3-3 libfftw3-dev libfftw3-double3 ```  ### Windows ...not supported yet. ## Installation ```sh $ npm i soundengine ``` ## Basic usage example ```javascript 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() ``` ## Api ### Devices To list the available devices ```javascript 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](http://www.portaudio.com/docs/latency.html) defaultLowOutputLatency | number | [See PortAudio docs](http://www.portaudio.com/docs/latency.html) defaultHighInputLatency | number | [See PortAudio docs](http://www.portaudio.com/docs/latency.html) defaultHighOutputLatency | number | [See PortAudio docs](http://www.portaudio.com/docs/latency.html) ### Engine methods The engine class actually has almost all the methods of a nodejs [EventEmitter](https://nodejs.org/api/events.html#events_class_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.* ### 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](http://www.portaudio.com/docs/latency.html) outputLatency | number | default high output latency | [See PortAudio docs](http://www.portaudio.com/docs/latency.html) ## 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. ## Todos * Implement fft stuff