imaadpcm

imaadpcm

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

About

IMA ADPCM codec in JavaScript.

Install

npm install imaadpcm

Browser

Use the compiled file in the /dist folder:

<script src="imaadpcm.min.js"></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>

Use

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);

In the browser

<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>

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 implemented as a ES6 module and also distributed as a CommonJS module, UMD module and a compiled script for browsers. If your system does not pick one automatically for you, you can pick one in the dist/ folder.

• The CommonJS is the one used by Node. It is served in the "main" field of this library's 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 "module" field points to "./index.js" and should be the default entry point.

If you are using a module bundler to compile a module that depends on this library you might need to specify what is the correct entry point as some bundlers will assume "browser". In general, you should point to "module".

webpack example:

module.exports = {
  entry: './index.js',
  resolve: {
    // tells webpack to use 'module' or 'main'
    // not 'browser'
    mainFields: ['module', 'main']
  },
  ...
};

References

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

Legal

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.

Changelog

version 3.0.0 (2018-06-22)

• ES6 module.