AC3.js

JavaScript AC-3 (ATSC A/52) decoder for the Aurora.js audio framework.

Installation

yarn add ac3.js

Usage

Simple

import {AC3SimpleDecoder} from 'ac3.js';
import fs from 'fs';

// This example loads an AC-3 audio file and writes the PCM data to file.
// The output file is in PCM signed 16-bit interleaved format.

// Initialize input and output stream
const inputStream = fs.createReadStream('example.ac3');
const outputStream = fs.createWriteStream('example.pcm');

// Initialize simple decoder
const simpleDecoder = new AC3SimpleDecoder(inputStream);

// Write PCM data to output stream (data is an Uint8Array)
simpleDecoder.on('data', (data) => {
    outputStream.write(data);
});

Aurora.js

import {AC3Decoder, AC3Demuxer} from 'ac3.js';
import AV from 'av';

// This example loads an AC-3 audio file and plays it.
// - In Node.js this should play the audio using the speaker module.
// - In the browser this should play the audio using the Web Audio API.

// Register demuxer and decoder
AV.Demuxer.register(AC3Demuxer);
AV.Decoder.register('ac3', AC3Decoder);

// Initialize player
const player = AV.Player.fromURL('https://example.org/example.ac3');

player.on('format', (format) => console.log('format', format));
player.on('duration', (duration) => console.log('duration', duration));
player.on('progress', (progress) => console.log('progress', progress));
player.on('ready', () => console.log('ready'));
player.on('end', () => console.log('end'));
player.on('error', (error) => console.error(error));

// Start the player
player.play();

For detailed information on how to use Aurora.js, check out the documentation.

Authors

• Danielle Huisman
• Karl Koscher

License

AC3.js is available under the terms of the MIT license.

Progress

Syntax implementation

• [x] syncframe
  • [x] syncinfo
  • [x] bsi
  • [x] audblk
  • [x] auxdata
  • [x] errorcheck

Decoding implementation

• [x] Input Bit Stream
• [x] Synchronization
• [ ] Error Detection
• [x] Unpack BSI
• [x] Unpack Side Information
• [x] Decode Exponents
• [x] Bit Allocation
• [x] Process Mantissas
• [x] Decoupling
• [x] Rematrixing
• [x] Inverse Transform
• [x] Window, Overlap/Add
• [x] Downmixing
• [x] PCM Output Buffer
• [x] Output PCM

Roadmap

• Support all downmixing modes
• Support Enhanced AC-3 (E-AC-3)
• Error detection
• Unit tests