Skip to main content

Multilingual Subtitles in the Player

Understanding VTT Manifest sidecar captions and how to use them with Videolinq

Updated over a week ago

When delivering live events, many organizations need captions or subtitles in multiple languages. Videolinq supports several captioning workflows, and one of the most flexible is VTT manifest sidecar captioning.

This article explains what a VTT manifest sidecar is, how it works, how to integrate it with your own video player, how to test it, and what new features are coming in January 2026 with the Videolinq Player.

What Is a VTT Manifest?

A VTT manifest sidecar is a text file that lists all available subtitle languages for a live stream. Instead of embedding captions into the video, your player loads each language separately from the manifest. Each WebVTT file updates in real time as Videolinq generates captions. The benefits of this workflow are:

  • Works with most modern HLS players.

  • Supports multilingual captions.

  • Keeps video and captions separate.

  • Ideal for live streaming workflows.

How Videolinq Generates It

When you select Player Integration under Channel → Captions, Videolinq:

  1. Activates the sidecar workflow for your live stream.

  2. Creates a unique VTT manifest URL.

  3. Lists all enabled languages inside the manifest.

  4. Updates each VTT track continuously during your event.

What Videolinq Provides

When you configure a live stream with captions, select the Channel/Captions/Player Integration option. Start the live stream and configure languages of choice. Start creating the captions. Click on the "Download" option. You will receive a ZIP folder containing a preview player, instructions, and a VTT manifest file. This is sample code and setup steps for:

  • Adding the manifest URL to your own player.

  • Enabling multilingual captions.

  • Testing live updates.

You may adapt these files to your own website or application.

Integrate With Your Player

General steps (applies to most HLS players):

  1. Load your HLS .m3u8 video stream.

  2. Add the VTT manifest URL as your caption source.

  3. Ensure your player supports multiple VTT tracks.

  4. Test captions during your live stream.

How to Test the Manifest

Recommended testing steps - open the included HTML file to verify:

  • Manifest loading

  • Real-time caption updates

  • Language switching

Open a VTT URL from the manifest in your browser to confirm live updates. Embed the manifest in your own player or website staging environment. Next, perform a network test. Ensure external caption URLs load successfully (HTTPS recommended).

FAQs

Does this work for VOD?
No, the manifest workflow is for live captioning.

How much delay?

Since Roman languages provide decent translation at a 2.5-second delay, but Asian languages require more time ( ~ 10-15 seconds), we recommend setting the delay to 1 minute.

Can I use my own player?
Yes, any player who supports VTT sidecar captions. Most players will require extra steps to configure them to accept multilingual subtitles.

Coming in January 2026

Videolinq will introduce built-in manifest support inside the Videolinq Player. When using:

  • A Videolinq Channel

  • Player Integration

  • The Videolinq HLS Player

you will get:

  • Automatic loading of the VTT manifest

  • Automatic multilingual captions in the player menu

  • ZIP download for your own player, or use Videolinq's

  • Easier publishing and live preview

This will significantly simplify the workflow.

Did this answer your question?