Closed Captioning

Resources

• OSU Digital Accessibility Center (DAC) - Live Captioning Guidance
• OSU Digital Accessibility Services (DAS) - Producing Accessible Multimedia Content

How to Create Video Captions

Automatic Captions with Human Review

Video hosting platforms such as Mediasite, Microsoft Stream, Zoom and YouTube have built-in captioning features. These features can significantly reduce the amount of time it takes to create captions. However, they sometimes get dialog incorrect, miss punctuation, and they cannot currently detect speakers, sound effects or music. Because of this, automatic captions must be reviewed and edited by a human to ensure accuracy.

Mediasite

The OSU instance of Mediasite has an AI-powered automated captioning feature built-in that generates very accurate captions of spoken dialog.

To use it:

• Go to Mediasite.
• Click “Add Presentation”.
• Click the “Choose File” button in the Add Video section and select the video file to upload.
• Give it a title and description and click the “Create Presentation” button.
• Once the video file is uploaded, captions will be generated automatically. Wait for an email with the subject line starting with “Captioning completed for…”
• Go back to Mediasite, then click on “My Presentations.”
• Click on the presentation.
• Click “Edit Captions.”
• Delete the automated caption messages (“TO REQUEST ACCESSIBLE CAPTIONS VISIT GO.OSU.EDU/CCHELP” and “CAPTIONS PROVIDED BY AUTOMATED TRANSCRIPTION.”)
• Listen to the video and adjust captions as needed. Ensure that you are indicating speakers, sound effects, music, etc.

To download the captions to create transcripts or for use on other platforms, such as YouTube or Microsoft Stream:

• Go to “My Presentations.”
• Click on the presentation.
• Click “Downloads.”
• Click “Captions (.dfxp)” or “Transcript (.txt).”

If the video was uploaded to Mediasite only for the automated captioning feature and does not need to be hosted there, we recommend deleting it after you have downloaded the captions.

Microsoft Stream

Videos that are uploaded to Teams, OneDrive, and SharePoint are available in Microsoft Stream. Microsoft Stream has a built-in automatic captioning feature that currently produces mostly accurate captions of spoken dialog.

See Microsoft’s documentation on creating and editing captions in Microsoft Stream. Once the captions are generated, listen to the video and adjust captions as needed. Ensure that you are indicating speakers, sound effects, music, etc.

Note: Microsoft Stream only supports caption files in the .vtt format. Content creators will need to convert the .dfxp to .vtt format (uploading captions to an online converter for certain types of videos may violate the Institutional Data Policy).

YouTube

YouTube can generate automatic captions. However, the captions often do not include punctuation and do not detect spoken dialog as well as the other options on this list, requiring longer manual review and remediation. It is recommended to use a different tool to generate and edit the captions, then upload the captions to the YouTube video.

PopeTech has a great article titled A complete guide for adding captions to YouTube videos that walks users through a step-by step process. Additionally, YouTube Help, provides the following instructional guides:

• Edit YouTube captions
• Add captions to YouTube videos

Zoom Cloud

In Zoom, the meeting organizer needs to enable automated captions. For online events, this is a way to meet the Digital Accessibility Policy in some circumstances with an approved exception (in other situations, a live captioner may be required; see Live Captioning).

If the video is going to be distributed after the meeting or event, the captions must be updated for accuracy. For editing captions, we recommend:

• Importing them into Mediasite to generate and edit new captions. These may be more accurate than the captions generated by Zoom.
• Editing the automated captions in the Zoom web portal.
• Downloading them from Zoom and uploading and editing them in Microsoft Stream.

If the automated captions are not accurate enough to be easily edited, you may consider downloading the MP4 file and hiring a captioning provider.

Professional Captioning

Vendors can create captions and transcripts for you.  

• For pre-recorded videos, see Hiring a Captioning Supplier.
• For live videos, see the Live Captioning page on the ADA Digital Accessibility Center’s website. Hiring a live CART captioning supplier may be required for certain types of events and is required if a participant requests the accommodation.