#stream-transcoder-2

FFmpeg based media transcoder that supports streams.

Forked from the original repo since it's not maintained.

Installing

yarn add stream-transcoder-2

npm i stream-transcoder-2

TypeScript types are included in the package.

FFmpeg is not installed with this package. Make sure you install it locally or use a package that provides it (e.g. ffmpeg-static).

Usage

Transcoding a file upload stream

Example using stream-body-parser.js

const express = require('express')
const StreamBodyParser = require('stream-body-parser')
const Transcoder = require('stream-transcoder')

const app = express()

const bodyParser = new StreamBodyParser(app)

bodyParser.process('video/*', function(stream, req, next) {
  const myGridFSWriteStream = 'Some MongoDB GridFS stream'

  new Transcoder(stream)
    .maxSize(320, 240)
    .videoCodec('h264')
    .videoBitrate(800 * 1000)
    .fps(25)
    .audioCodec('libfaac')
    .sampleRate(44100)
    .channels(2)
    .audioBitrate(128 * 1000)
    .format('mp4')
    .on('finish', function() {
      next()
    })
    .stream()
    .pipe(myGridFSWriteStream)
})

app.post('/', function(req, res) {
  res.send(200) // File uploaded
})

app.listen(3000)

In the above example the video is transcoded as it is being uploaded, and then piped directly into the database. So when the route is being called, the video is transcoded and stored.

Documentation

Transcoder

Transcoder is an EventEmitter.

This class transcodes from one media format to another. It supports both files and streams as input and/or output. Some formats are not suited for streaming, in which case the Transcoder will emit an error, but most formats are.

new Transcoder(options)

• options Object - A readable stream.
• options.source Stream | string - Source to parse, either a readable stream or a file path.
• options.ffmpegPath [string] - Optional path to ffmpeg executable. If this is null it will be set to process.env.FFMPEG_PATH || 'ffmpeg''

Event: 'metadata'

• metadata Object - Metadata of input and output streams.

Emitted when metadata is available for both input and output streams. If no output is specified (by using transcoder.exec()), only input streams will be described.

This an example of a transcoding process metadata.

{
  "input": {
    "streams": [
      {
        "type": "video",
        "codec": "h264",
        "bitrate": 10131000,
        "fps": 25,
        "size": {
          "width": 1280,
          "height": 720
        },
        "aspect": 1.7777777777777777,
        "colors": "yuv420p"
      },
      {
        "type": "audio",
        "codec": "aac",
        "samplerate": 44100,
        "channels": 2,
        "bitrate": 106000
      }
    ],
    "duration": 250068,
    "synched": true
  },
  "output": {
    "streams": [
      {
        "type": "video",
        "codec": "h264",
        "bitrate": 800000,
        "size": {
          "width": 320,
          "height": 180
        },
        "aspect": 1.7777777777777777,
        "colors": "yuv420p"
      },
      {
        "type": "audio",
        "codec": "aac",
        "samplerate": 44100,
        "channels": 2,
        "bitrate": 128000
      }
    ]
  }
}

Event: 'progress'

• progress Object - Object describing current progress.

Emitted when progress has been made in the transcoding.

This is an example of the progress object. Where progress.progress is a percentage of the total transcoding job.

{
  "frame": 508,
  "fps": 253,
  "quality": 16,
  "size": 1553408,
  "time": 20041,
  "bitrate": 608000,
  "progress": 0.08014220132124063
}

Event: 'finish'

Emitted when transcoding is complete.

Event: 'error'

• error Error - The error that occured.

Emitted when FFmpeg exits with an error.

transcoder.videoCodec(codec)

• codec String - Name of the video codec. As an example h264.

Sets the video codec.

Returns transcoder object.

Notice: Supported video codecs depends on your FFmpeg installation. Running ffmpeg -codecs from your terminal will list the supported codecs.

transcoder.videoBitrate(bitrate)

• bitrate Number or String - The bitrate of the encoded video. Both 1280000 or 128 kbit can be passed.

Sets the video bitrate.

Returns transcoder object.

transcoder.fps(fps)

• fps Number - Frames per second.

Sets the number of frames per second.

Returns transcoder object.

transcoder.format(format)

• format String - Output format.

Sets the output format.

Returns transcoder object.

Notice: Supported formats also depends on you FFmpeg installation. Running ffmpeg -formats from your terminal will list the supported formats.

transcoder.maxSize(width, height)

• width Number - Maximum width of video.
• height Number - Miximum height of video.

Sets the output video size, shrinking to fit the size to maintain aspect ratio. The output video will be within the defined size, but with aspect ratio is preserved.

Returns transcoder object.

transcoder.minSize(width, height)

• width Number - Minimum width of video.
• height Number - Minimum height of video.

Sets the output video size, scaling it to have a minimum of both directions, while maintaining aspect ratio.

transcoder.size(width, height)

• width Number - Minimum width of video.
• height Number - Minimum height of video.

Sets the output video size, not maintaining aspect ratio if it doesn't fit.

Returns transcoder object.

transcoder.passes(passes)

• passes Number - The number of encoder passes.

Sets the number of encoder passes.

Returns transcoder object.

transcoder.aspectRatio(ratio)

• ratio Number - The desired aspect ratio. As an example 1.7777777.

Sets the video aspect ratio.

Returns transcoder object.

transcoder.audioCodec(codec)

• codec String - Name of the audio codec. As an example mp3 or aac.

Sets the audio codec.

Returns transcoder object.

Notice: Supported audio codecs depends on your FFmpeg installation. Running ffmpeg -codecs from your terminal will list the supported codecs.

transcoder.sampleRate(rate)

• rate Number - Audio sample rate. As an example 44100.

Sets the audio sample rate.

Returns transcoder object.

transcoder.channels(channels)

• channels Number - Number of audio channels.

Sets the number of audio channels.

Returns transcoder object.

transcoder.audioBitrate(bitrate)

• bitrate Number - The audio bitrate.

Sets the audio bitrate.

Returns transcoder object.

transcoder.captureFrame(time)

• time Number - Time of frame in milliseconds.

Capture a single frame at time. Sets up transcoder to jpeg output.

Returns transcoder object.

transcoder.stream()

Returns a writeable stream that will emit the transcoded media data.

transcoder.writeToFile(file)

• file String - Path of filename.

Writes transcoded media data to file.

Returns transcoder object.

transcoder.exec()

Executes the transcoder without outputting any data. This is useful if you only need metadata for a media file.

Returns child process.

transcoder.custom(key, value)

• key String - The key for the parameter
• value String [optional] - The value for the parameter.

Adds a custom parameter to the FFmpeg command line - this is for all your special needs that is currently not implemented as a function in the Transcoder.

As an example:

.custom('ss', '00:30:00')

Translates to on the FFmpeg command line:

ffmpeg -ss 00:30:00