@sarakusha/ebml

Yet another library for parsing EBML. The main difference from existing libraries is browser support. Instead of a Node Stream API and buffers, the Web Streams API and typed arrays (Uint8Array) are used. Of course you can use it for node.js too. Another difference is that the library is built automatically from official EBML and matroska specifications.

This library is written in typescript from scratch and is not a fork of existing libraries.

Caveat

This version of the library only supports EBML decoding.

Usage

The EbmlDecoder class is implemented as a TransformStream of the Streams API. The input to this transform function should be binary EBML, provided in a Uint8Array. The output of the stream is a series of Element objects.

// The base interface
interface Element {
  // The id of the EBML tag in hexadecimal format.
  id: HexID;
  // The data type of the EBML tag
  type: ElementType;
  // The name of the EBML tag
  name: string;
  // The total size of the tag in bytes
  size: number;
  // Tag attributes from the official specification.
  spec?: ElementSpec;
}

type ElementType =
  | 'master' /* master element (contains other EBML sub-elements of the next lower level) */
  | 'uinteger' /* unsigned integer. Some of these are UIDs, coded as 128-bit numbers */
  | 'integer' /* signed integer */
  | 'float' /* IEEE-754 floating point number */
  | 'string' /* printable ASCII text string */
  | 'utf-8' /* printable utf-8 Unicode text string */
  | 'date' /* a 64-bit signed timestamp, in nanoseconds after (or before) `2001-01-01T00:00UTC` */
  | 'binary' /* binary data, otherwise uninterpreted */
  | 'unknown';

There are two base 'flavors' of Element:

• MasterElement is element that contains one or more child elements.
• ContentElement is a tag element only contains data.