DecibelMeter

Monitor dB Levels Using HTML5 Audio API

DecibelMeter allows you to monitor the noise level using your device's microphone(s) from within a web page or node-webkit application.

``javascript
// connect to first audio input device found
new DecibelMeter.listenTo(0, (dB, percent, value) => console.log(dB))
`

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I have tested this in Chrome and Firefox for Windows and Android.
iOS support is not available yet.

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You can try the DecibelMeter now: DecibelMeter example

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npm install --save decibel-meter

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Import DecibelMeter as ES6 module

`javascript
import DecibelMeter from 'decibel-meter'
`

Or, using a script tag

`html

`

Create a decibel meter
`javascript
const meter = new DecibelMeter('unique-id');
`

Get a list of audio sources on the device
`javascript
// resolves with array of MediaDeviceInfo objects, filtered by type: audioinput
meter.sources.then(sources => console.log(sources))
`

Connect to an audio source
`javascript

// first method

meter.sources.then(sources => {
meter.connect(sources[0])
})

// second method

meter.connectTo('default') // find audioinput by deviceId, and connect if possible
meter.connectTo(0) // find the first audioinput, and connect if possible

// handling errors

meter.connectTo('not-real').catch(err => alert('Connection Error'))
`

Do something with the decibel data
`javascript
const level = document.getElementById('db-level')

meter.on('sample', (dB, percent, value) => level.textContent = ${dB} dB) // display current dB level
`

Start listening to audio source
`javascript
meter.listen() // "sample" callback set above will now receive data
`

Stop listening to audio source
`javascript
meter.stopListening()
`

Disconnect from the audio source entirely
`javascript
meter.disconnect() // returns Promise
`

Connect to a source, add a 'sample' event listener, and start listening to the connected source, in one terse command
`javascript
meter.listenTo(0, (dB, percent, value) => level.textContent = ${dB} dB)
`

Multiple meters on one page
`javascript
var meter1 = new DecibelMeter('meter-1')
var meter2 = new DecibelMeter('meter-2')

DecimelMeter.meters // all meters created on this page

meter1 === DecimelMeter.getMeterById('meter-1'); // true
`

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DecibelMeter has its own events dispatcher, and supports the following Events

- change
- connect
- disconnect
- sample

change - the meter's listening state has changed

`javascript
meter.on('change', listening => {
if (listening)
level.classList.add('active')
else
level.classList.remove('active')
})
`

connect - the meter successfully connected to an audioinput

`javascript
meter.on('connect', (source, previous) => {
console.log(
Connected to ${source.label}
Disconnected from ${previous.label}
)
})
`

disconnect - the meter was disconnected from a source

sample` - the meter received decibel data from the source