Video and Audio Accessibility Guidelines


The accessibility purpose of captions and transcripts is to provide an equally effective experience and timely access to the same information that people without disabilities receive when they watch a video or listen to live or recorded audio.

These guidelines are intended primarily to help University staff, faculty, and students ensure video and audio content is accessible to people with auditory disabilities, as well as to those with other disabilities that require captioning, transcripts, or audio descriptions as accommodations.

They are also meant to encourage universal design practices, which extends the benefits of accessibility to anyone in the  intended audience.

Captions, Transcripts, and Audio Descriptions

Although captions is used an a general term, audio can be transcribed and made available in three ways:

  • Captions provide a synchronized text description of the audio track and appear within the media player window. Captions can be generated live, either by artificial intelligence or by a professional captioner. They can also be generated or edited after the creation of the video or audio recording, depending on the platform or service used. Captions are most helpful to people with auditory disabilities, non-native speakers of the language used, as an aid to understanding, in noisy environments, and when there is a need to turn off or keep the volume low.
    • Closed captions exist as a separate track and can be turned on and off.
    • Open captions are burned into the video or audio file itself and cannot be turned off.
    • Live captions can be done by a person who is trained to create them, or by AI. Automated captions are available in key technologies used at Princeton, including Zoom, PowerPoint, and Google Slides. Automated captions do not include description of audio beyond what is spoken, and they may or may not identify the speaker.
  • Transcripts provide a text description of audio, but unlike captions, they do not provide descriptions of other relevant sounds. They can be time-indexed but exist in a separate text file outside the video player. Transcripts are more suitable for recordings of spoken audio only, with no other sounds or video described.
  • Audio descriptions narrate a video's visual elements, such as characters, costumes, actions, body language, setting, scene changes, and on-screen text. They supplement the regular audio track and are inserted into pauses in dialogue. Audio descriptions are especially helpful to people with visual disabilities. Because creating audio descriptions requires special training to write and synchronize with the video, you should work with a captioning service as described below.

Videos added to Media Central are automatically machine captioned. Because captioning is automatic, you should not caption your videos beforehand. Once you upload them to Media Central, any existing captions will be overwritten. See below for instructions on editing captions to improve their accuracy.

Course-related videos may also be posted to Panopto, where they are also automatically machine captioned. For support, contact the McGraw Center for Teaching and Learning.

Quality Assurance in Captioning

To ensure captions and transcripts are high quality and accurate, either edit captions that have been automatically generated, or procure professional captioning services. When requesting video production from the University’s Video Production Support team, you should indicate, or inquire, whether the video needs to be delivered with professional captions.

The accuracy of automated captioning continues to improve. Automated captioning alone is generally not sufficient to support formal accommodations for people with disabilities. In such cases, when automated captioning is used it should only be considered as a first step until the captions are corrected, either in-house or by a professional captioner.

    Professional Captioning Services

    When working with a captioner, provide materials in advance, such as the names of the presenters and those referenced, technical terms, specialized language, references (such as to papers or student presentations), and copies of speeches.

    List of registered suppliers (Login required)

    Editing Captions in Media Central to Improve Accuracy

    Once you upload a video, the captioning process will begin and generally takes a few hours. Once the process is complete:

    1. Go to Media Central
    2. Log in.
    3. Pull down the menu under your profile name, and select My Media.
    4. In the list of videos that appears, click on the title of the video you want to edit.
    5. When the video detail page opens, pull down the ACTIONS menu and select Captions & Enrich.
    6. Select the pencil (edit) icon.
    7. When the Closed Captions Editor page opens, click on the first caption entry, which will take you to the start of the spoken audio in the video. The select the video play button to follow along.
    8. Check back and forth as you listen to the video and read the caption entries. Start and stop the video as needed, so that you can correct the captions to match the spoken audio.
    9. Save your work every few minutes.

    Live Captioning for Videoconferencing

    Professional Live Captioning (CART)

    Also known by the technical term "Communication Access Real-time Translation" (CART), live captions are provided by a professional captioner as an event takes place. The captioner is either in attendance or participating remotely via web conference. Online, the captions are shown over the bottom portion of the video window. In an in-person event, the captions are shown on a separate screen in the room. 

    For Major Events

    1. When you submit a request for Media Event/Production Support, indicate on the form the need for live captioning.
    2. You must then also separately schedule live captioning. We recommend CaptionFirst.
    3. CaptionFirst will then contact Video Production Support to coordinate captioning.

    For Zoom Webinars

    1. To enable professional live captioning, you must first submit a request for a Video / Web Conferencing Account.
    2. Once your account has been established, schedule live captioning. We recommend ACS Captions or CaptionFirst.
    3. Contact Video Production Support with any questions or concerns.

    For Zoom Meetings

    1. All staff Zoom accounts are Meeting accounts, so no account request is required.
    2. Schedule professional live captioning with either ACS Captions or CaptionFirst.

    Automated Live Captions

    Machine-generated live captions are increasingly accurate and helpful for many people, including those with disabilities. Automated live captions may not be sufficient for those who require captions as an accommodation. In such instances, meeting organizers and presenters should follow an attendee's accommodation need: in the case of a member of the University community, as documented by the Office of Disabilities, Human Resources, or the Office of the Dean of the Faculty; or in the case of a member of the public, as requested.

    Zoom Automated Live Captions

    For attendees to view live captions, the host must first enable the feature in their Zoom settings. Attendees then have the option to turn captions on for themselves. Note that captions are not saved.

    Meeting host

    To enable automated live captions:

    1. Ensure the Closed Captioning function in your Zoom settings is on, and the Enable live transcription service option underneath is checked.
    2. In the meeting, the Zoom toolbar, select Live Transcript.
    3. When the Live Transcript menu opens, select Enable Auto-Transcription.

    To disable live automated live captions:

    1. In the Zoom toolbar, select Live Transcript.
    2. When the Live Transcript menu opens, select Disable Auto-Transcription.
    Meeting attendee

    To view automated live captions:

    1. In the Zoom toolbar, select Live Transcript.
    2. When the Live Transcript menu opens, select an option:
      • Show Subtitle displays captions on the screen
      • View Full Transcript displays captions with the speaker's name and a time stamp within the transcript window
      • Subtitle Settings… opens the Accessibility Settings window, where you can adjust the font size for both the captions and the Chat window

    To turn off automated live captions:

    1. In the Zoom toolbar, select Live Transcript.
    2. When the Live Transcription menu opens, select Hide Subtitle.

    For Individual Accommodations

    1. Students should email the Office of Disability Services, staff should consult the HR accommodations policy, and faculty should contact the Office of the Dean of the Faculty.
    2. ODS coordinates with vendors, typically ACS Captions or White Coat Captioning.
    3. ODS also coordinates with internal offices as needed.