Recording & Playback

Audio Recording

import { PulseAudio } from '@janakj/pulseaudio.js';

const pa = new PulseAudio("Test client for @janakj/pulseaudio.js");
await pa.connect();

Recording audio with pulseaudio.js is straightforward. Create a new record stream with the method createRecordStream, pipe the stream to a wav write, and pipe the wav writer to a file. When you are done recording, unpipe the streams and destroy the record stream.

import * as fs from 'fs';
import * as wav from 'wav';
import { PA_SAMPLE_FORMAT, sampleSize } from '@janakj/pulseaudio.js';

// Configure the sample format: 44.1 kHz, stereo, 16 bits per sample
const rate = 44100, channels = 2, format = PA_SAMPLE_FORMAT.S16LE;

// Create a new record stream with the given sample format connected
// to the default source (sound card)
const stream = await pa.createRecordStream({
    sampleSpec : { rate, format, channels }
});

// Create a new wav file writer with the above sample format
const writer = new wav.Writer({
    sampleRate : rate,
    channels,
    bitDepth : sampleSize[format] * 8
});    

// Write the recorded audio to file audio.wav
const file = fs.createWriteStream('audio.wav');

// Pipe the record stream to the write and the writer to the
// filesystem stream
stream.pipe(writer);
writer.pipe(file);

// Keep recording for 10 seconds. Once the time is up, unpipe
// the streams and destroy the record the stream
setTimeout(() => {
    stream.unpipe();
    writer.unpipe();
    stream.destroy();
}, 10000);

It is also possible the specify the maximum length of the recording in bytes by passing a maximumLength property to createRecordStream. In that case, the record stream will end automatically upon recording the given number of bytes, without the need to set a timer.

Audio Playback