https://github.com/reneraab/pcm-volume

Change the volume of pcm data in node.js.
https://github.com/reneraab/pcm-volume

Last synced: 4 months ago
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Change the volume of pcm data in node.js.

• Host: GitHub
• URL: https://github.com/reneraab/pcm-volume
• Owner: reneraab
• License: mit
• Created: 2014-08-05T22:52:59.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2020-08-24T12:32:20.000Z (over 4 years ago)
• Last Synced: 2024-08-11T09:55:24.680Z (4 months ago)
• Language: JavaScript
• Size: 9.77 KB
• Stars: 27
• Watchers: 6
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
pcm-volume

===========

This module changes the volume of a given PCM data stream. At the moment only signed 16bit PCM data is supported, also I'm not quite sure about this as my knowledge about PCM is very limited.

I don't know whether this is the right way to do things. Feel free to contact me/open a pull request if you want to add something.

Install

-------

Install with `npm install pcm-volume` or clone from GitHub and `npm install`.

How to use

----------

Pipe an existing stream into an instance of pcm-volume. You can get a PCM-stream from node-lame for example.

This example reads the file music.mp3 and changes the volume to 50% after 5seconds.

```js

var Speaker = require("speaker");

var lame = require("lame");

var fs = require("fs");

var volume = require("pcm-volume");

var readable = fs.createReadStream("music.mp3");

// see node-lame documentation for more information

var decoder = new lame.Decoder({

    channels: 2,

    bitDepth: 16,

    sampleRate: 44100,

    bitRate: 128,

    outSampleRate: 22050,

    mode: lame.STEREO

});

// Initialize speaker

var speaker = new Speaker();

// Create a volume instance

var v = new volume();

// Wait 5s, then change the volume to 50%

setTimeout(function() {

    v.setVolume(0.5);

}, 5000)

v.pipe(speaker); // pipe volume to speaker

decoder.pipe(v); // pipe PCM data to volume

readable.pipe(decoder); // pipe file input to decoder

```

API

---

pcm-volume is a Transform Stream (see https://nodejs.org/api/stream.html#stream_class_stream_transform for more information). Pipe in your PCM data and pipe out PCM data with a different volume.

Use setVolume(v) to set the volume (v is a float between 0 and roughly 1.5 also you can go higher but it sounds like crap).