https://github.com/hackergrrl/goertzel-stream

:musical_note: Detects the presence of a single frequency in a stream of signal samples.
https://github.com/hackergrrl/goertzel-stream

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:musical_note: Detects the presence of a single frequency in a stream of signal samples.

• Host: GitHub
• URL: https://github.com/hackergrrl/goertzel-stream
• Owner: hackergrrl
• License: mit
• Created: 2016-04-05T00:03:33.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2016-04-05T14:24:19.000Z (over 8 years ago)
• Last Synced: 2024-05-13T16:25:50.061Z (5 months ago)
• Language: JavaScript
• Homepage:
• Size: 15.6 KB
• Stars: 7
• Watchers: 4
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

        
# goertzel-stream

> Detects the presence of a single frequency in a stream of signal samples.

# example

```js

var goertzel = require('goertzel-stream')

var Generator = require('audio-generator')

var freq = 697

// Generate a sine wave at 697 Hz

var gen = Generator(function (time) {

  if (time > 1) {

    return 0

  } else {

    return Math.sin(Math.PI * 2 * time * freq)

  }

})

// Detection stream looking for the 697 Hz frequency

var detect = goertzel(freq)

// Pipe the signal into the detector

gen.pipe(detect)

detect.on('toneStart', function (tones) {

  console.log('start', tones)

})

detect.on('toneEnd', function (tones) {

  console.log('start', tones)

})

```

```

{ '697': { start: 0 } }

{ '697': { start: 0, end: 1 } }

```

# api

## var detect = goertzel(freq, opts={})

Returns a WriteStream set to detect frequencies. `freq` can be a single number

or an array of frequencies to detect.

`opts` is mandatory, and has some required and optional parameters:

- `opts.sampleRate` (required) - how many samples are taken per second. For best

  results, this should be at least twice the [Nyquist

  frequency](https://en.wikipedia.org/wiki/Nyquist_frequency). 2.5x works well.

- `opts.testsPerSecond` (optional) - How many tests for the frequency to perform

  per second's worth of samples. Defaults to 100.

Now you're ready to pipe in an audio source!

## detect.on('toneStart', function (tones) { ... })

Emitted when a tone begins. `tones` is an object mapping a frequency to its

start time.

```

{ '697': { start: 0 } }

```

## detect.on('toneEnd', function (tones) { ... })

Emitted when a detected tone ends. `tones` is an object mapping a frequency to

its start time and end time.

```

{ '697': { start: 0, end: 1 } }

```

# install

With [npm](https://npmjs.org/) installed, run

```

$ npm install goertzel-stream

```

# license

MIT