Accessibility

The purpose of this document is to describe how to use the video playback accessibility features for audio descriptions and closed captions.

IMPORTANT:

There is some general confusion about the term “audio descriptions” in the industry. This stems from the fact that there are multiple usages of the term. The first usage of the term refers to playing an audio track in a video that is separate from the original audio track. This additional audio track contains spoken words to describe what is happening in the video when there are breaks in the video’s original audio track. The second usage is technical usage. Web browser vendors have implemented a method of using machine generated spoken audio, to “read aloud” words from a time-coded text file. This functionality is generally available on MacOS & iOS Safari, but only has preliminary support from other web browser vendors. This technology is still evolving and the adoption/deployment of it can be monitored here.

The good news is that we support both.

Audio descriptions from separate audio tracks

As mentioned above separate audio tracks can be added to HLS and DASH adaptive streaming technologies. This supports switching audio tracks during playback to be able to listen to an audio track that is enhanced with additional “audio descriptions” of what is happening in the video. You can think of this like a “director’s cut” of a movie, where you hear commentary from the director during dialog downtimes.

Creation of separate audio tracks happens during the content creation process, the audio tracks need to be timed with the original audio, in order to not have any audible conflicts with the main  audio track. Effectively you are recording an additional audio track with spoken words integrated into it.

To help visualize this, you can imagine this audio description track:

The top waveform being the main audio of the video, the bottom waveform being spoken words when the main audio track is quiet or playing music.

An audio description track combines the top and bottom waveforms together into a single MP3 file for playback.

Adding an audio description track to a video

Navigate to the video details page in the dashboard.

In the Audio tracks section, click the “+” button to upload one or more audio tracks.

Enter a label for the audio track (this can be no more than 20 characters, as it will appear in the video player’s selection interface).

Once you have provided a label and audio track file, just hit “Save” and you’re done. Optionally, you can select a different language code, as needed.

It is recommended to use this in combination with closed captions, but not time-coded spoken text - choose whichever makes the most sense for your application.

Audio descriptions from time-coded text

Audio descriptions are an extended form of accessibility, similar to closed captions in that they leverage the WebVTT file format to deliver a specific user experience. When enabled by a user in their web browser, audio descriptions provide time-coded audio that provides more detail about what is happening in a video in addition to the video’s audio track. For video assets that only have background music, audio descriptions explain to the user what is happening in the video visually. For users who do not have the audio functionality enabled in their browser, the video player provides an option to enable the description text as an overlay, similar to how captions work. Only one can be enabled at a time.

Automated closed captions

By default whenever a video is uploaded to the platform, it is automatically processed by our AI closed caption generation system, which extracts and identifies spoken language. The AI system will identify the correct language used in the video and generate the appropriate closed caption file. The system also generates a transcript, which can be used for SEO purposes. Both file and transcript are found in the platform on each video details screen.

Manual closed captions

For any video asset, you can manually manage closed captions, as desired. This includes the addition & removal of closed caption files, as well as enabling up to 30 different languages per video.

Adding caption or description files

Uploading caption and description files is an easy process, from the video details screen simply click the “+” icon in the Accessibility area..

A dialog opens that allows you to set the file type (caption or description), choose a language, and select or drag your caption file. Note “description” type files cannot be set as a default, so there is no option for that.

Caption or description files can be in 2 formats, SRT or VTT. Our video player natively leverages the VTT format, however you can upload SRT files and the platform will convert them for you automatically.

If you are uploading your own files, please ensure correct formatting of the file. You can compare your files to our sample files if you encounter any issues.

Sample VTT File Sample SRT File

Once you have completed the form, click “SAVE”. The system will ingest yourfile and you will see it listed in the Accessibility section. Below is an example of a closed caption file, as well as an audio description file.

You can download the files for reference, remove them or add more files for additional language support as needed.

Descriptions and closed captions have been tested with popular screen reader software on both Windows (NVDA) and MacOS (VoiceOver). For both platforms, the text displayed by the video player is readable by the screen reader.

Currently, there is limited native web browser support for descriptions to be automatically read audibly. The status of the native web browser support can be monitored here.

The following languages are supported:

• Arabic
• Catalan
• Czech
• Danish
• Dutch
• English
• Finnish
• French
• German
• Greek
• Hebrew
• Hindi
• Hungarian
• Icelandic
• Indonesian
• Italian
• Japanese
• Korean
• Malay
• Polish
• Portuguese
• Punjabi
• Romainian
• Serbian
• Spanish
• Swedish
• Thai
• Turkish
• Ukrainian
• Vietnamese

The video player will automatically ingest and understand how to display the captions and descriptions out of the box. Nothing further is required. If you wish to utilize your own player, you can access the accessibility files using the provided metadata from our Content API.

If you have any questions, feel free to contact support@creatable.io and we’ll be happy to help.