EBML Demuxer

A lightweight EBML demuxer for extracting specific tracks from WebM/Matroska files.

Installation

npm install ebml-demuxer

or

yarn add ebml-demuxer

or cdn

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/ebml-demuxer.iife.full.min.js"></script>
<script>
  const { EbmlDemuxer } = window.EBMLDemux
</script>

Usage

const { EbmlDemuxer } = require('ebml-demuxer')

const demuxer = new EbmlDemuxer({ tracks: ['video'] }) // or ['video', 'audio'], ['subtitle']

demuxer.on('video', (data, codec) => {
  // Handle video frame data
})
demuxer.on('keyframe', (timecode, track) => {
  // handle keyframes for each track
})

demuxer.on('end', () => {
  console.log('Demuxing complete')
})

demuxer.write(buffer)  // Write EBML data
demuxer.end()          // Signal end of input

API

new EbmlDemuxer(options)

• options.tracks - Array of tracks to extract ("video", "audio", "subtitle", )
• options.isLive - live video demuxing

Events

• "video", [data: Buffer, codec: string] - Emitted for video frames
• "audio", [data: Buffer, codec: string] - Emitted for audio frames
• "subtitle", [data: Buffer, codec: string] - Emitted for subtitle frames
• "end" - Emitted when processing completes

Example

const fs = require('fs/promises')
const path = require('path')
const { EbmlDemuxer } = require('ebml-demuxer')

const demuxer = new EbmlDemuxer({ tracks: ['video', 'audio'] })
const videoChunks = []
const audioChunks = []

demuxer.on('video', (data, codec) => videoChunks.push(data))
demuxer.on('audio', (data, codec) => audioChunks.push(data))

demuxer.on('end', async () => {
  console.log('Demuxing complete')
  await Promise.all([
    fs.writeFile(path.join(__dirname, 'video.webm'), Buffer.concat(videoChunks)),
    fs.writeFile(path.join(__dirname, 'audio.webm'), Buffer.concat(audioChunks)),
  ])
})

const main = async () => {
  const buffer = await fs.readFile(path.join(__dirname, 'input.webm'))
  demuxer.write(buffer)
  demuxer.end()
}
main()