Transloadit

Synthesize speech in documents

🤖/text/speak synthesizes speech in documents.

/text/speak Robot

You can use the audio that we return in your application, or you can pass the audio down to other Robots to add a voice track to a video for example.

Another common use case is making your product accessible to people with a reading disability.

Usage example

Synthesize speech from uploaded text documents, using a female voice in American English:

{
  "steps": {
    "synthesized": {
      "robot": "/text/speak",
      "use": ":original",
      "provider": "aws",
      "voice": "female-1",
      "target_language": "en-US"
    }
  }
}

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 videos, you can also add "interlaced": true to detect whether the video is interlaced. This combines the cheap ffprobe field_order flag with a bounded idet sampling pass over the first frames of the source, exposing interlaced, field_order, and a diagnostic interlace_detection object under file.meta. This is computationally expensive and billed accordingly.

    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.

  • user_meta

    Record<string, any>(default: {})

    Adds custom metadata to each file emitted by this Robot without modifying the file’s contents.

    The values are merged with any existing user_meta carried by the input file. If both objects contain the same key, this Robot’s value takes precedence. Assembly Variables are supported, for example { "internal_file_id": "${file.id}" }.

  • 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 input Steps with as to pass semantic intent to robots: 
      {
  "use": [
    {
      "name": ":original",
      "as": "image"
    },
    {
      "name": ":original",
      "as": "mask"
    }
  ]
}

  • prompt

    string | null

    Which text to speak. You can also set this to null and supply an input text file.

  • provider

    auto | aws | gcp(default: "auto")

    Chooses the best provider based on your request.

    Set this to "aws" or "gcp" to force a specific provider.

  • target_language

    string(default: "en-US")

    The written language of the document. This will also be the language of the spoken text.

    The language should be specified in the BCP-47 format, such as "en-GB", "de-DE" or "fr-FR". Please consult the list of supported languages and voices.

  • voice

    female-1 | female-2 | female-3 | female-child-1 | male-1 | male-child-1(default: "female-1")

    The gender to be used for voice synthesis. Please consult the list of supported languages and voices.

  • ssml

    boolean(default: false)

    Supply Speech Synthesis Markup Language instead of raw text, in order to gain more control over how your text is voiced, including rests and pronounciations.

    Please see the supported syntaxes for AWS and GCP.

Demos

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