Requesting Auto Captions

Introduction

Brightcove Auto Captioning is a platform-level service that allows you to automatically generate captions for new or existing videos in 31 different languages (provided you have an audio track for the language specified). Like all speech-to-text services Auto Captioning is not 100% accurate, but it provides a quick and easy way to generate captions right in Video Cloud.

Video Cloud uses the following process to determine the source that will be used to generate the captions.

• If the video has default audio track, that will be used as the captions source file (supported by default in the Media module)
• If the video has no default audio track but a master/mezzanine file exists, that will be used as the source file (supported by default in the Media module)
• If the video has no default audio track or master/mezzanine files, but audio tracks are specified in the Dynamic Ingest call, the specified audio track will be used (not yet supported in the Media module)
• If the video has no default audio track, no master/mezzanine files, and no audio track is specified, captions cannot be generated

Setup

The setup for Dynamic Ingest requests is the same, whether you are ingesting a video, images, audio tracks, WebVTT files, requesting auto captions, or all of these:

Request URL

https://ingest.api.brightcove.com/v1/accounts/{{account_id}}/videos/{{video_id}}/ingest-requests
        

Authentication

Authentication requires an access token passed as a Bearer token in an Authorization header:

          Authorization: Bearer {access_token}
        

To get access tokens, you will need client credentials (see below). For the process of obtaining an access token, see Get Access Tokens.

Note on S3

If your source files will be pulled from a protected S3 bucket, you will need to set a bucket policy to allow Video Cloud to access the files. See Using Dynamic Ingest with S3 for details.

Use cases

Here are some typical use cases

Create auto-captions for new ingestions or retranscoding

{
  "master": {
    "use_archived_master": true
  },
  "profile": "multi-platform-standard-static-with-mp4",
  "transcriptions": [
    {
      "srclang": "EN-us",
      "kind": "captions",
      "label": "English",
      "status": "published",
      "default": true
    }
  ],
  "priority": "normal"
}

Create auto-captions when ingesting an audio track

{
  "audio_tracks": {
    "merge_with_existing": true,
    "masters": [
      {
        "language": "fr-FR",
        "variant": "alternate",
        "url": "https://support.brightcove.com/test-assets//audio/celtic_lullaby.m4a"
      }
    ]
  },
  "transcriptions": [
    {
      "srclang": "fr-FR",
      "kind": "captions",
      "label": "french-FR",
      "status": "published",
      "default": false,
      "input_audio_track": {
        "language": "fr-FR",
        "variant": "alternate"
      }
    }
  ]
}

Create auto-captions for an existing video using the digital master

{
  "transcriptions": [
    {
      "srclang": "fr-FR",
      "kind": "captions",
      "label": "french-FR",
      "default": false
    }
  ]
}

Create auto-captions for an existing video defining the audio tracks

{
  "transcriptions": [
    {
      "srclang": "en-US",
      "kind": "captions",
      "label": "english-EN",
      "default": false,
      "input_audio_track": {
        "language": "en-US",
        "variant": "main"
      }
    },
    {
      "srclang": "fr-FR",
      "kind": "captions",
      "label": "french-FR",
      "default": false,
      "input_audio_track": {
        "language": "fr-FR",
        "variant": "alternate"
      }
    }
  ]
}

Request body fields for auto captions

The table below shows the request body fields for auto captions.

input_audio_track fields

Supported languages

Currently, auto captions are limited to the following languages