HLS Transcoder

THIS PACKAGE IS STILL UNDER ACTIVE DEVELOPMENT, API CHANGES CAN AND LIKELY WILL HAPPEN REGARDLESS OF WHETHER THEY ARE DOCUMENTED BELOW

An FFMPEG Wrapper heavily inspired by simple-hls, to transcode Multi-bitrate HLS videos.

Installation:

Via npm:

npm install hls-transcoder

Prerequisites

ffmpeg and ffprobe

hls-transcoder requires both ffmpeg, and ffprobe. If ffmpeg and ffprobe are installed on your system, and added to PATH, hls-transcoder will try invoking each program via ffmpeg and ffprobe respectively.

Alternatively, you can use pre-compiled binaries, ie with @ffmpeg-installer/ffmpeg and @ffprobe-installer/ffprobe, and specify the ffmpegPath and ffprobePath properties in the options object.

---

Usage:

Basic Setup

Typescript:

import Transcoder from 'hls-transcoder'

async function transcodeVideo() {
  const transcoder = new Transcoder(`[input-video.mp4/.mov/.avi/etc]``${__dirname}/output`)

  transcoder.on('error', (err) => {
    console.error(err)
  })

  try {
    const hlsPath = await transcoder.transcode()
    console.log('Successfully Transcoded Video')
  } catch (err) {
    console.log(err)
  }
}

transcodeVideo()

OR

Use @ffmpeg-installer/ffmpeg and @ffprobe-installer/ffprobe to use precompiled binaries of ffmpeg and ffprobe without having to install on your system.

Typescript:

import Transcoder from 'hls-transcoder'
import ffmpeg from '@ffmpeg-installer/ffmpeg'
import ffprobe from '@ffprobe-installer/ffprobe'

async function transcodeVideo() {
  const transcoder = new Transcoder(`[input-video.mp4/.mov/.avi/etc]``${__dirname}/output`, {
    ffmpegPath: ffmpeg.path,
    ffprobePath: ffprobe.path
  })

  transcoder.on('error', (err) => {
    console.error(err)
  })

  try {
    const hlsPath = await transcoder.transcode()
    console.log('Successfully Transcoded Video')
  } catch (err) {
    console.log(err)
  }
}

transcodeVideo()

Documentation:

Options

When creating a new instance of the Transcoder class, you can supply a third parameter options as an object which will override the default behaviour / settings of hls-transcoder. The possible options and their default values are as follows:

• allowUpscaling
  • Description: When set to false renditions will only be transcoded if the original video is the same resolution or higher than that of the rendition being transcoded. When set to true
  • Default: false
  • Type: boolean | undefined
• ffmpegPath
  • Description: Allows specifying which PATH hls-transcoder should use when invoking an ffmpeg child_process
  • Default: ffmpeg
  • Type: string | undefined
• ffprobePath
  • Description: Allows specifying which PATH hls-transcoder should use when invoking an ffprobe child_process
  • Default: ffprobe
  • Type: string | undefined
• renditions
  • Description: The various resolutions and bitrates hls-transcoder will use when transcoding video files
  • Default: See default renditions
  • Type: RenditionOptions | undefined

Setting event handlers

The Transcoder class extends EventEmitter and will emit the following events:

• 'error'
• 'stderr'
• 'progress'
• 'end'

'error' - transcoding errors

transcoder.on('error', (err) => {
  console.error(err)
})

'stderr' - information ffmpeg sends via the command line

transcoder.on('stderr', (data) => {
  console.log(data)
})

'progress' - transcoding progress information

transcoder.on('progress', (progress) => {
  console.log(progress)
})

The progress event is emitted everytime ffmpeg reports progress information. The progress object contains the following keys:

• frame: total processed frame count
• fps: framerate at which FFmpeg is currenlty processing

'end' - information about ffmpegs exit status

transcoder.on('end', (data) => {
  console.log(data)
})

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Ongoing TODOS:

• Progress Bar
• Add option for outputPath param per Rendition
• Add option for Renditions per Resolution
• Fix ffmpeg stderr and stdout processing / parsing
  • Currently in progress
• Test and/or handle .ts file name overflows
  • ie. '1080p_0.ts' where number of ts segments > 10
  • Figured out, default behavior is to just keep adding numbers, ie 11, 12, 13 - so this shouldn't be an issue unless there's a use case where a program is expecting the filenames to match a specfic pattern like that
• Create dir automatically if doesn't exist?
  • Should do this, right now it fails silently if output dir doesn't exist
• Option to enable / disable overwrite?
• Invalid dimensions for renditions appear to fail silently