Extract thumbnails from videos

🤖/video/thumbs extracts any number of images from videos for use as previews.

Usage example

{
  "steps": {
    "thumbnailed": {
      "robot": "/video/thumbs",
      "use": ":original",
      "count": 10,
      "ffmpeg_stack": "v6"
    }
  }
}

Parameters

• interpolate

  boolean | Record<string, boolean>

  Controls whether Assembly Variables are interpolated for individual instruction fields.

  By default, most Robot instruction fields interpolate Assembly Variables. Set this to false to treat every instruction field as literal text, or set an individual field path to false to treat only that field as literal text. For Robot-specific fields that are literal by default, set this to true or set that field path to true to opt back into interpolation.

  Use field names such as path, or dotted paths such as ffmpeg.vf for nested objects.

• output_meta

  Record<string, boolean> | boolean | Array<string>

  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 images, you can also add "blurhash": true to extract a BlurHash string — a compact representation of a placeholder for the image, useful for showing a blurred preview while the full image loads.

  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.

• ignore_errors

  boolean | Array<meta | execute> (default: [])

  Ignore errors during specific phases of processing.

  Setting this to ["meta"] will cause the Robot to ignore errors during metadata extraction.

  Setting this to ["execute"] will cause the Robot to ignore errors during the main execution phase.

  Setting this to true is equivalent to ["meta", "execute"] and will ignore errors in both phases.

• 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"
      ]
    }
    

  • You can also tag an input Step with as to pass semantic intent to robots:
  • You can also tag input Steps with as to pass semantic intent to robots:
    

    {
      "use": [
        {
          "name": ":original",
          "as": "image"
        },
        {
          "name": ":original",
          "as": "mask"
        }
      ]
    }
    

  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: "v6.0.0")

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

• count

  string | number (default: 8)

  The number of thumbnails to be extracted. As some videos have incorrect durations, the actual number of thumbnails generated may be less in rare cases. The maximum number of thumbnails we currently allow is 999.

  The thumbnails are taken at regular intervals, determined by dividing the video duration by the count. For example, a count of 3 will produce thumbnails at 25%, 50% and 75% through the video.

  To extract thumbnails for specific timestamps, use the offsets parameter.

• offsets

  Array<string | number> | Array<string> (default: [])

  An array of offsets representing seconds of the file duration, such as [ 2, 45, 120 ]. Millisecond durations of a file can also be used by using decimal place values. For example, an offset from 1250 milliseconds would be represented with 1.25. Offsets can also be percentage values such as [ "2%", "50%", "75%" ].

  This option cannot be used with the count parameter, and takes precedence if both are specified. Out-of-range offsets are silently ignored.

• format

  jpeg | jpg | png (default: "jpeg")

  The format of the extracted thumbnail. Supported values are "jpg", "jpeg" and "png". Even if you specify the format to be "jpeg" the resulting thumbnails will have a "jpg" file extension.

• width

  string | number

  The width of the thumbnail, in pixels. Defaults to the original width of the video.

• height

  string | number

  The height of the thumbnail, in pixels. Defaults to the original height of the video.

• resize_strategy

  crop | fit | fillcrop | min_fit | pad | stretch (default: "pad")

  One of the available resize strategies.

• background

  string (default: "#00000000")

  The background color of the resulting thumbnails in the "rrggbbaa" format (red, green, blue, alpha) when used with the "pad" resize strategy. The default color is black.

• rotate

  0 | 90 | 180 | 270 | 360 (default: 0)

  Forces the video to be rotated by the specified degree integer. Currently, only multiples of 90 are supported. We automatically correct the orientation of many videos when the orientation is provided by the camera. This option is only useful for videos requiring rotation because it was not detected by the camera.

• input_codec

  string

  Specifies the input codec to use when decoding the video. This is useful for videos with special codecs that require specific decoders.

Demos

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