Why subtitles are essential for OTT streaming services

For OTT streaming services in particular, subtitles play a critical role in improving accessibility and reaching viewers across different regions, platforms, and devices.

In fact, accessibility isn’t just a best practice - it’s also a legal requirement. Under the European Accessibility Act (EAA), subtitles are mandatory across the EU, while in the US, the Americans with Disabilities Act (ADA) requires streaming services to provide accessible media. So if you aren’t using subtitles on your service yet, you should! 

 Accedo One supports a variety of subtitle formats and workflows, making it easy for media services to add subtitles and create a more inclusive viewing experience.
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How do subtitles work? 

Subtitles work by synchronising written text with the audio track of a video. Each subtitle is time-coded, meaning it is programmed to appear on screen at the exact moment the corresponding dialogue is spoken, and then disappear when the line ends.

Behind the scenes, this process is managed through a subtitle file, which contains both the text and the timing information. When a video plays, the media player reads the subtitle file and displays the text at the right moment, overlaid on the picture.
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How Accedo One handles subtitles

Supported subtitle file types

The file type you need to provide depends largely on what each integrated OVP supports, as Accedo One works with the subtitle formats offered by each video provider.

• Brightcove supports WebVTT, SRT, DFXP, and SCC. You can create text tracks in the Brightcove toolset and add them in the Tracks tab for the respective video.‍
• JW Player supports WebVTT and SRT, with captions added directly in the video dashboard. ‍
• Accedo One’s VCMS supports WebVTT and TTML. To add a text track, go to Content Manager > Video > Text Track.
• If you are using a custom OVP, speak to your Accedo One representative for guidance on supported subtitle formats and integration steps.
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Accedo One supports both text-based subtitles and captions, as well as audio formats such as dubbed languages and descriptive audio tracks.

Subtitle naming and fallback

The name or label of each subtitle track is displayed in the subtitle selection view exactly as it is defined in the manifest. If these fields are missing, fallback logic is applied to help the end user find the correct text track.

In practice, the system always aims to show the clearest possible label to the viewer. If no information is available, it defaults to Unknown.

It is therefore important to define the name or label fields properly, so you can control what viewers see.

Supported language codes

Accedo One supports ISO 639-1 language codes as well as a selection of ISO 639-3 language codes.

List of 639-1 language codes

Currently supported ISO 639-3 language codes include:

• cmn – Mandarin
  yue – Yue Chinese
• eng – English
  
  

Is there any difference between subtitles and closed captions? 

By definition, subtitles and closed captions are slightly different. Subtitles provide spoken dialogue in text form, often for translation purposes. Closed captions, on the other hand, go further by including dialogue along with descriptions of sound effects, music, and speaker cues, making the content fully accessible.

In Accedo One, both are handled in the same way — as text tracks. If you want to indicate that a text track is a closed caption rather than a subtitle, you can customise the label to include this information (for example, English (CC)).

More information on subtitles and closed captions 

On captions and subtitles from an Accessibility viewpoint

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