WebVTT subtitle side-loading

August 2024

What’s changing

MK.IO now supports side-loading of WebVTT subtitle tracks for assets.

Who is impacted

Anyone who is using MK.IO for VOD transcoding and willing to enrich their VOD assets with one or more subtitle files.

Why you would use this / Why it matters

When transcoding VOD content, the source asset may not have the appropriate subtitling data to process. Subtitles can come from a separate metadata source or can be generated through an AI pipeline on the side. In such cases, MK.IO offers a simple API solution to add a subtitle file to an existing asset, ensuring that your users have access to subtitles during playback.

MK.IO allows you to set the language and accessibility parameters for the subtitle track you are adding.

Additional details

Side-loading of a subtitle track is done through a new transform type in MK.IO.

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If the manifest has been played back before inserting a subtitle track, there will be a delay of up to 60s before the manifest will contain the subtitles, due to cache settings.

For more details, refer to Track Insertion transform.

Getting started

Adding a new subtitle track to an existing asset is as simple as creating a new job using a track insertion transform: you specify the WebVTT file to use as input and the destination asset to use as output.

This operation is only available using the API, a sample VTT track addition transform is provided in this article.

Availability & rollout plan

WebVTT subtitle side-loading is available in all regions starting August 19th 2024.

Metering & Pricing

There is no additional charge associated to this feature.