Auto-Captions

Requires WPMediaVerse Pro - This feature is available exclusively in the Pro version.

WPMediaVerse Pro transcribes video and audio files using the OpenAI Whisper API and attaches the result as a WebVTT caption file. Captions are served with the media player and can be edited via the REST API.

Requirements

• An OpenAI API key with access to the Whisper transcription endpoint
• The media file must be a supported audio or video format (MP3, MP4, M4A, WAV, WEBM, OGG)

Enabling Auto-Captions

Go to Media > Settings > Video and configure the following options.

Option	Option Key	Default	Description
Auto-Generate Captions	mvs_pro_captions_auto	0	Automatically transcribe each uploaded video or audio file
Caption Language	mvs_pro_captions_language	(auto)	Optional source-language hint passed to the provider
Caption Provider	mvs_pro_captions_provider	whisper	Transcription provider

The OpenAI API key is read from the free plugin's existing OpenAI API Key setting (the mvs_openai_api_key option, configured under Media > Settings > AI & Moderation). There is no separate Pro Whisper key field - captions reuse the same key as the rest of the AI features.

When Auto-Generate Captions is on, WPMediaVerse Pro queues a transcription job via Action Scheduler immediately after a file is stored. The caption file is saved once the Whisper API responds.

Caption File Storage

WebVTT files are stored at:

/wp-content/uploads/mvs-captions/{media_id}.vtt

If cloud storage is active, the VTT file is also uploaded alongside the media file.

REST API

Base URL: /wp-json/mvs-pro/v1/

GET /media/{id}/captions

Retrieve the caption file content and metadata for a media item.

Response:

{
  "status": "complete",
  "language": "en",
  "vtt_url": "https://example.com/wp-content/uploads/mvs-captions/123.vtt",
  "generated_at": "2025-03-28T10:00:00Z"
}

status can be none, pending, complete, or failed.

POST /media/{id}/captions/generate

Queue Whisper transcription for the media item. Requires ownership or admin (manage_mvs_settings). No body is required.

curl -X POST https://yoursite.com/wp-json/mvs-pro/v1/media/123/captions/generate \
  -H "X-WP-Nonce: NONCE"

Response: 202 Accepted with the current status object.

GET /media/{id}/captions/status

Poll the transcription job status for a media item.

Response: 200 OK with { "status": "pending" | "complete" | "failed" | "none" }.

PUT /media/{id}/captions

Replace the caption content with edited VTT text. Use this to correct transcription errors.

Body (JSON):

{
  "content": "WEBVTT\n\n00:00:00.000 --> 00:00:04.000\nHello and welcome.\n\n00:00:04.500 --> 00:00:09.000\nToday we are covering...",
  "language": "en"
}

Response: 200 OK with the updated caption metadata.

DELETE /media/{id}/captions

Remove the caption file and reset the caption status to none.

Response: 204 No Content.

WebVTT Format

WPMediaVerse Pro always stores captions in WebVTT format. Caption content you submit through the API must begin with the WEBVTT header - content that does not start with that header is rejected. There is no automatic SRT-to-VTT conversion; convert SRT to WebVTT before uploading.

Example VTT file:

WEBVTT

00:00:00.000 --> 00:00:04.000
Hello and welcome to this video.

00:00:04.500 --> 00:00:09.000
Today we are covering the main topic.

Editing Captions

To correct a transcription, replace the stored VTT through the REST API with PUT /media/{id}/captions, passing the edited WebVTT content in the content field (see the REST API section above). The content must begin with the WEBVTT header.