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vivekagr / ts-ebml

EBML encoder and decoder

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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

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 run setup # install cli tools
npm run init  # install libraries
npm run build # build js code
npm run lint  # tslint
npm run doc   # typedoc
npm run check # type check
npm run test  # build test
npm run example # build example

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

About

EBML encoder and decoder

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Language:TypeScript 56.2%Language:JavaScript 38.8%Language:HTML 5.0%