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  • License MIT

ebml decoder and encoder

Package Exports

  • ts-ebml
  • ts-ebml/dist/EBML.min.js
  • ts-ebml/lib/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (ts-ebml) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

ts-ebml

ebml encoder and decoder written in TypeScript.

Fork of node-ebml

It is a fork of https://github.com/themasch/node-ebml

install

npm install ts-ebml --save

usage

show EBML structure on console

$ ts-ebml foo.webm
0	m	0	EBML
5	u	1	EBMLVersion 1
9	u	1	EBMLReadVersion 1
13	u	1	EBMLMaxIDLength 4
17	u	1	EBMLMaxSizeLength 8
21	s	1	DocType webm
28	u	1	DocTypeVersion 2
32	u	1	DocTypeReadVersion 2
36	m	0	Segment
48	m	1	Info
53	u	2	TimecodeScale 1000000
...

try to convert a MediaRecorder WebM to seekable WebM

$ ts-ebml -s input.webm | cat > seekable.webm

node

import * as ebml from 'ts-ebml';
const fs = require('fs');

const decoder = new ebml.Decoder();

fs.createReadStream('media/test.webm').on('data', (buf)=>{
  const ebmlElms = decoder.decode(buf);
  console.log(ebmlElms);
});

browser

<script src="./dist/ebml.min.js"></script>
<script>
const decoder = new ebml.Decoder();

fetch('media/test.webm')
  .then((res)=> res.arrayBuffer() )
  .then((buf)=>{
    const ebmlElms = decoder.decode(buf);
    console.log(ebmlElms);
  });  
</script>

bundle

import * as ebml from 'ts-ebml';

const decoder = new ebml.Decoder();

fetch('media/test.webm')
  .then((res)=> res.arrayBuffer() )
  .then((buf)=>{
    const ebmlElms = decoder.decode(buf);
    console.log(ebmlElms);
  });

features

  • get WebP frame from MediaRecorder WebM VP8 Stream
  • create seekable webm from media-recoder
  • create playable webm to media-stream-api from media-recorder

see src/test.ts and src/example_seekable.ts

stable API

class Decoder {
  constructor();
  decode(chunk: ArrayBuffer): EBMLElementDetail[];
}

class Encoder {
  constructor();
  encode(elms: EBMLElementBuffer[]): ArrayBuffer;
}

type EBMLElementBuffer = MasterElement | ChildElementBuffer;
type EBMLElementDetail = (MasterElement | ChildElementValue) & ElementDetail;

type MasterElement = {
  name: string;
  type: "m";
  isEnd: boolean;
  unknownSize?: boolean;
};
type ChildElementBuffer = {
  name: string;
  type: "u" | "i" | "f" | "s" | "8" | "b" | "d";
  data: Buffer;
};
type ChildElementValue = ChildElementBuffer & {
  value: number|string|Buffer|Date;
};
type ElementDetail = {
  tagStart: number;
  tagEnd: number;
  sizeStart: number;
  sizeEnd: number;
  dataStart: number;
  dataEnd: number;
};
namespace tools {
  export function readVint(buffer: Buffer, start: number): null | ({length: number; value: number; });
  export function writeVint(val: number): Buffer;
  export function readBlock(buf: ArrayBuffer): EBML.SimpleBlock;
}

develop

npm install
npm run build   # build js code
npm run lint    # tslint
npm run doc     # typedoc
npm run lint   # type check (watch)
npm test        # build and run tests

debugging tools

license

MIT

related info

related issues

media recorder seekable webm

chrome

firefox

others

media recorder media source gap

chrome

others

chrome

firefox

related works