Convert videos to HLS and MPEG-Dash

This Robot accepts all types of video files and audio files. Do not forget to use Step bundling in your use parameter to make the Robot work on several input files at once.

This Robot is normally used in combination with 🤖/video/encode. We have implemented video and audio encoding presets specifically for MPEG-Dash and HTTP Live Streaming support. These presets are prefixed with "dash/" and "hls/". View a HTTP Live Streaming demo here.

Required CORS settings for MPEG-Dash and HTTP Live Streaming

Playing back MPEG-Dash Manifest or HLS playlist files requires a proper CORS setup on the server-side. The file-serving server should be configured to add the following header fields to responses:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
Access-Control-Allow-Headers: *

If the files are stored in an Amazon S3 Bucket, you can use the following CORS definition to ensure the CORS header fields are set correctly:

[
  {
    "AllowedHeaders": ["*"],
    "AllowedMethods": ["GET"],
    "AllowedOrigins": ["*"],
    "ExposeHeaders": []
  }
]

To set up CORS for your S3 bucket:

1. Visit https://s3.console.aws.amazon.com/s3/buckets/
2. Click on your bucket
3. Click "Permissions"
4. Edit "Cross-origin resource sharing (CORS)"

Storing Segments and Playlist files

The Robot gives its result files (segments, initialization segments, MPD manifest files and M3U8 playlist files) the right metadata property relative_path, so that you can store them easily using one of our storage Robots.

In the path parameter of the storage Robot of your choice, use the Assembly Variable ${file.meta.relative_path} to store files in the proper paths to make the playlist files work.

Usage example

{
  "steps": {
    ":original": {
      "robot": "/upload/handle"
    },
    "encoded_480p": {
      "robot": "/video/encode",
      "use": ":original",
      "preset": "hls/480p",
      "ffmpeg_stack": "v6"
    },
    "encoded_720p": {
      "robot": "/video/encode",
      "use": ":original",
      "preset": "hls/720p",
      "ffmpeg_stack": "v6"
    },
    "encoded_1080p": {
      "robot": "/video/encode",
      "use": ":original",
      "preset": "hls/1080p",
      "ffmpeg_stack": "v6"
    },
    "hls_bundled": {
      "robot": "/video/adaptive",
      "use": {
        "steps": [
          "encoded_480p",
          "encoded_720p",
          "encoded_1080p"
        ],
        "bundle_steps": true
      },
      "technique": "hls",
      "playlist_name": "my_playlist.m3u8"
    }
  }
}

Parameters

• output_meta

  Record<string, boolean> | boolean

  Allows you to specify a set of metadata that is more expensive on CPU power to calculate, and thus is disabled by default to keep your Assemblies processing fast.

  For images, you can add "has_transparency": true in this object to extract if the image contains transparent parts and "dominant_colors": true to extract an array of hexadecimal color codes from the image.

  For videos, you can add the "colorspace: true" parameter to extract the colorspace of the output video.

  For audio, you can add "mean_volume": true to get a single value representing the mean average volume of the audio file.

  You can also set this to false to skip metadata extraction and speed up transcoding.

• result

  boolean (default: false)

  Whether the results of this Step should be present in the Assembly Status JSON

• queue

  "batch"

  Setting the queue to 'batch', manually downgrades the priority of jobs for this step to avoid consuming Priority job slots for jobs that don't need zero queue waiting times

• force_accept

  boolean (default: false)
  

    Force a Robot to accept a file type it would have ignored.
  

  By default Robots ignore files they are not familiar with. 🤖/video/encode, for example, will happily ignore input images.

  With the force_accept parameter set to true you can force Robots to accept all files thrown at them. This will typically lead to errors and should only be used for debugging or combatting edge cases.

• use

  string | Array<string> | Array<object> | object

  Specifies which Step(s) to use as input.

  • You can pick any names for Steps except ":original" (reserved for user uploads handled by Transloadit)
  • You can provide several Steps as input with arrays:
    

    {
      "use": [
        ":original",
        "encoded",
        "resized"
      ]
    }
    

  Tip

  That’s likely all you need to know about use, but you can view Advanced use cases.

• ffmpeg

  object

  A parameter object to be passed to FFmpeg. If a preset is used, the options specified are merged on top of the ones from the preset. For available options, see the FFmpeg documentation. Options specified here take precedence over the preset options.

• ffmpeg_stack

  "v5" | "v6" | "v7" | string (default: "v5.0.0")

  Selects the FFmpeg stack version to use for encoding. These versions reflect real FFmpeg versions. We currently recommend to use "v6.0.0".

• width

  string | number | null

  Width of the new video, in pixels.

  If the value is not specified and the preset parameter is available, the preset's supplied width will be implemented.

• height

  string | number | null

  Height of the new video, in pixels.

  If the value is not specified and the preset parameter is available, the preset's supplied height will be implemented.

• preset

  …

  Converts a video according to pre-configured settings.

  If you specify your own FFmpeg parameters using the Robot's and/or do not not want Transloadit to set any encoding setting, starting ffmpeg_stack: "v6", you can use the value 'empty' here.

• technique

  "dash" | "hls" (default: "dash")

  Determines which streaming technique should be used. Currently supports "dash" for MPEG-Dash and "hls" for HTTP Live Streaming.

• playlist_name

  string

  The filename for the generated manifest/playlist file. The default is "playlist.mpd" if your technique is "dash", and "playlist.m3u8" if your technique is "hls".

• segment_duration

  string | number (default: 10)

  The duration for each segment in seconds.

• closed_captions

  boolean (default: true)

  Determines whether you want closed caption support when using the "hls" technique.

Demos

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