kontainer-js
v2.4.0
Published
A media file format generator/parser that exposes a React-like API.
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Kontainer
A media file format generator/parser that exposes a React-like API.
Kontainer aims to fully support the MP4 (ISO Base Media file format: ISO/IEC 14496-12) and WebM file format. The library can be used on Node.js and in the browser.
Install
Overview
API
A media file like MP4 and WebM is composed of nested objects. In Kontainer, each object, e.g. MP4 Box, is represented as a KontainerElement
which is similar to the ReactElement
.
The actual media data (audio and video chunks) and the metadata are represented as a props
object and passed to the KontainerElement
as its attributes.
import Kontainer from 'kontainer-js';
export default class MP4 {
constructor(width, height) {
Kontainer.use('mp4'); // format (mp4|webm) needs to be set before any API call
this.width = width;
this.height = height;
}
render() {
return (
<file>
<ftyp majorBrand="isom" />
<moov>
<mvhd creationTime={new Date()} modificationTime={new Date()} timeScale={1} nextTrackId={4} />
<trak>
<tkhd creationTime={new Date()} modificationTime={new Date()} trackId={1} width={this.width} height={this.height} />
<mdia>
...
</mdia>
</trak>
</moov>
</file>
);
}
}
The above code can be transpiled into the calls to createElement()
using babel
and a dedicated plugin.
// Kontainer.createElement()
// Accepts: type, props, children...
// Returns: KontainerElement
return Kontainer.createElement('file', null,
Kontainer.createElement('ftyp', {majorBrand: 'isom'}),
Kontainer.createElement('moov', null,
Kontainer.createElement('mvhd', {creationTime: new Date(0), modificationTime: new Date(), timeScale: 1, nextTrackId: 4}),
Kontainer.createElement('trak', null,
Kontainer.createElement('tkhd', {creationTime: new Date(0), modificationTime: new Date(), trackId: 1, width: 640, height: 480}),
Kontainer.createElement('mdia', null,
...
// KontainerElement can be a child of other elements to compose a large nested tree.
)
)
)
);
Once an element is obtained, it can be serialized into a byte stream using render()
.
// Kontainer.render()
// Accepts: KontainerElement
// Returns: Buffer (in node) or ArrayBuffer (in browser) that contains a media stream
buffer = Kontainer.render(element);
On the other hand, you can create a KontainerElement from a byte stream.
// Kontainer.createElementFromBuffer()
// Accepts: Buffer (in node) or ArrayBuffer (in browser) that contains a media stream [, offset=0]
// Returns: KontainerElement.
element = Kontainer.createElementFromBuffer(buffer, offset);
You can also create your hook and process a byte stream progressively. (This works only for Node.js)
const input = fs.createReadStream('./test.mp4');
const transform = Kontainer.transform((type, props, children) => {
if (type === 'tkhd') {
// Change video dimensions
props.width /= 2;
props.height /= 2;
}
});
input.pipe(transform).pipe(process.stdout);
JSX
To transpile JSX into createElement()
calls together with your ES.next code, you need to install babel
and its plugins.
$ npm install babel-cli
$ npm install babel-preset-es2015
$ npm install babel-plugin-transform-kontainer-js
Put a .babelrc file in the source directories that contain JSX.
{
"presets": ["es2015"],
"plugins": ["transform-kontainer-js"]
}
Then use the babel
command to transpile the code.
$ babel src/ -d dist/
See the plugin code for the details.
CLI
A simple parser for displaying the structure of a media file.
Usage:
kontainer filePath [options]
Example:
kontainer /path/to/file
cat /path/to/file | kontainer
Options:
-h, --help Print help
-v, --version Print version
Development
// Install
$ git clone [email protected]:kuu/Kontainer.git
$ cd Kontainer
$ npm install
// Test
$ npm test
// Build client libs
$ npm run build
// --> ./lib/kontainer.deb.js (uncompressed with debug messages)
// --> ./lib/kontainer.js (uncompressed)
// --> ./lib/kontainer.min.js (compressed)
// --> ./lib/kontainer.map.js (source map)