Introduction
The automated captions feature allows you to enable automatic audio transcribing to create captions for your live stream.
If you are new to the Live API, review the Create a Live Stream Using the Brightcove Live API document.
Setup
Live automated captions are available to Video Cloud customers.
- Contact Brightcove customer support to enable your account.
- Once you have enabled your account, you can turn on automated captions for each live stream that you create.
Turn on automated captions
To create a job with transcribe support for automated captions, add the following attributes to the regular Job creation payload:
{
"transcribe_state": "ON"
}
Example
This example body will create a live job with automated captions.
Request
POST https://api.bcovlive.io/v1/jobs
Content-Type: application/json
X-API-KEY: your_API_key
Request body
{
"live_stream": true,
"region": "us-west-2",
"reconnect_time": 1800,
"live_sliding_window_duration": 1,
"transcribe_state": "ON",
"outputs": [
{
"label": "hls1080p",
"live_stream": true,
"width": 1920,
"height": 1080,
"video_codec": "h264",
"h264_profile": "main",
"video_bitrate": 2400,
"segment_seconds": 6,
"keyframe_interval": 60
},
{
"label": "hls720p",
"live_stream": true,
"width": 1280,
"height": 720,
"video_codec": "h264",
"h264_profile": "main",
"video_bitrate": 1843,
"segment_seconds": 6,
"keyframe_interval": 60
},
{
"label": "hls480p",
"live_stream": true,
"width": 640,
"height": 360,
"video_codec": "h264",
"h264_profile": "main",
"video_bitrate": 819,
"segment_seconds": 6,
"keyframe_interval": 60
}
]
}
Set the language
You can set the language for the generated captions. In this example, the language is set to English, US:
{
"transcribe_state": "ON",
"transcribe_options": {
"language_code": "en-US"
}
}
Turn on captions mid stream
Enabling automated captions is supported after the job has been created any time independent of the job state. New Endpoints have been defined and shall be shared shortly to accomplish the sam.
The endpoint would be:
PATCH https://alive-auth.api.brightcove.com/v2/accounts/{{account_id}}/{{job_region}}/jobs/{{job_id}}/transcribe
Payload:
{
"transcribe_state": "ON"/"OFF"
}
Limitations
Here is a list of limitations with the live automated captions feature:
- Transcription is only supported for non low latency HLS Streams. Low Latency HLS and DASH streams don't have transcription support at this time.
- You cannot enable Transcribe support for Jobs already created in your account.
- Currently, we provide captions only in one language. We don't support multi language captions at the moment. The Default language for captions is set to
en-US
- Automated captions work best for jobs less than 4 hours in duration. If your live stream exceeds 4 hours, captions may drop for a brief interval.
- The accuracy threshold for automated captions is around a 30% word error rate, which can fluctuate.
- Currently, automated captions will not be saved when creating a clip or VOD from the live event.