imaadpcm

Copyright (c) 2018 Rafael da Silva Rocha.
https://github.com/rochars/imaadpcm

IMA ADPCM codec in JavaScript.

Install

npm install imaadpcm

Use

ES6

import imaadpcm from imaadpcm.js:

import * as imaadpcm from 'imaadpcm.js';
let adpcmSamples = imaadpcm.encode(pcmSamples);

Node

const imaadpcm = require("imaadpcm");
let adpcmSamples = imaadpcm.encode(pcmSamples);

Browser

Use the compiled file in the /dist folder:

<script src="imaadpcm.min.js"></script>
<script>
    var adpcmSamples = imaadpcm.encode(pcmSamples);
    pcmSamples = imaadpcm.decode(adpcmSamples);
    var adpcmBlock = imaadpcm.encodeBlock(pcmBlock);
    pcmBlock = imaadpcm.decodeBlock(adpcmBlock);
</script>

Or get it from the jsDelivr CDN:

<script src="https://cdn.jsdelivr.net/npm/imaadpcm@3"></script>

Or get it from unpkg:

<script src="https://unpkg.com/imaadpcm@3"></script>

Or as a ES6 module in modern browsers from jspm:

<script type="module">
  import imaadpcm from 'https://dev.jspm.io/imaadpcm';
  // ...
</script>

Examples

Files:

const imaadpcm = require("imaadpcm");

// Compressing all the samples in a file
// Only 16-bit samples are supported
adpcm_samples = imaadpcm.encode(samples);

// Decompressing all the samples in a file
// 256 block align is assumed by default
samples = imaadpcm.decode(adpcm_samples);

// Decompressig all the samples in a file
// Using a different block align (1024)
samples = imaadpcm.decode(adpcm_samples, 1024);

Streaming:

const imaadpcm = require("imaadpcm");

// Decompressing a ADPCM block
// 256 block align is assumed by default
samples = imaadpcm.decodeBlock(adpcm_block);

// Decompressing using a different block align (1024)
samples = imaadpcm.decodeBlock(adpcm_block, 1024);

// Compressing PCM samples into a block of ADPCM samples
// Only blocks of 505 samples are supported as input
// Only 16-bit samples are supported as input
adpcm_samples = imaadpcm.encodeBlock(sample_block);

API

/**
 * Encode 16-bit PCM samples into 4-bit IMA ADPCM samples.
 * @param {!Array<number>} samples A array of samples.
 * @return {!Array<number>}
 */
function encode(samples) {}

/**
 * Decode IMA ADPCM samples into 16-bit PCM samples.
 * @param {!Array<number>} adpcmSamples A array of ADPCM samples.
 * @param {number} blockAlign The block size.
 * @return {!Array<number>}
 */
function decode(adpcmSamples, blockAlign=256) {}

/**
 * Encode a block of 505 16-bit samples as 4-bit ADPCM samples.
 * @param {!Array<number>} block A sample block of 505 samples.
 * @return {!Array<number>}
 */
function encodeBlock(block) {}

/**
 * Decode a block of ADPCM samples into 16-bit PCM samples.
 * @param {!Array<number>} block A adpcm sample block.
 * @return {!Array<number>}
 */
function decodeBlock(block) {}

Distribution

This library is a ES6 module also distributed as a CommonJS module, UMD and a compiled script for browsers.

• The CommonJS is the one used by Node. It is served in the "main" field of package.json
• The UMD module is compatible with Node, AMD and browsers. It is served in the "browser" field.
• The compiled dist is browser-only and should be the one served by CDNs.
• The ES6 dist is imaadpcm.js, served as "module" in package.json

You may load both imaadpcm.umd.js and imaadpcm.min.js in the browser with <script> tags.

References

http://www.cs.columbia.edu/~hgs/audio/dvi/
https://github.com/acida/pyima

LICENSE

Copyright (c) 2018 Rafael da Silva Rocha.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.