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Captions are required for all educational videos. Read below to find out how they work in Canvas.

Accurate captions are an essential component of making your videos accessible. While UCSD is fully committed to ensuring the accessibility of all educational content, the benefits of including captions extend beyond addressing the needs of students with disabilities. Given that learning preferences are a variety of continuums (rather than binary categories such as visual learner/aural learner), making captions available to students provides them with choice on how they consume educational content.

What are Captions?

Captions typically display at the bottom of a video player and contain a textual representation of all relevant audible information that occurs in a video. They're essential for viewers with auditory disabilities to be able to perceive the educational content of your video.

Captions are different than transcripts. Caption files are specially-formatted text documents that include timecodes that tell the player when a particular piece of text should be onscreen. A transcript is basically just the text with no timecodes, often presented in a large block with no paragraph breaks.

How Do Captions Work in Canvas / Kaltura?

Here are the main things you need to know:

  • All videos added to Kaltura after 13 June 2020 should have some sort of machine captions. For videos added before that time, you can request machine captions. (See the instructions below.)
  • Machine captions are about 70% accurate on average.
  • We recommend that you edit your captions to ensure they're accurate. (Otherwise they aren't particularly helpful to students with relevant disabilities.)
  • Captions can be edited within Canvas, or downloaded, edited in a text editor, and uploaded.
  • Videos that come to Kaltura as a result of our Zoom integration will carry Zoom captions with it.
  • Our default embed and Media Gallery players will display captions in the player when played.
  • Kaltura also generates a transcript based on the captions that displays in a widget below the player. The transcript itself is not editable, but the captions are. Any changes you make to the captions will be reflected in the transcript.
  • The transcript widget is initially collapsed and can be expanded. Transcripts can also be downloaded.
  • For embedded videos, the transcript widget has a known bug where it reserves "empty space" below the player when the widget is collapsed.

Whys, Requirements, Caveats

Why You Might Want to...

  • Request Captions
    • You have videos produced before 13 June 2020 that don't have captions at all
  • Edit Captions
    • You want to ensure the accuracy of your captions
    • Accurate captions allow you to create a document from the transcript of your video
    • Having accurate captions addresses a variety of learning styles (since many students without disabilities like to watch videos with captions on)

Prerequisites for...

  • Requesting Captions
    • A video uploaded and completely processed
    • The video in question doesn't already have Kaltura-generated machine captions requested or completed
  • Editing Captions
    • A video with existing captions


  • When requesting Captions
    • The machine captions you're requesting are about 70% accurate
    • The turnaround time for machine captions can be up to 2 times the length of the video
  • When editing Captions
    • Editing captions is time-consuming
    • If you use the Closed Caption Editor in Canvas, you can lose your edits if you don't save them periodically
  • About Captions Generally
    • There are no profanity filters. While it's unlikely (presumably) that you'll use any derogatory language in your videos, the AI running the machine captioning can accidentally misinterpret and put offensive words in the captions.

How to Request Captions

All videos added to Kaltura ("My Media") after 13 June 2020 will automatically have captions requested and inserted. They will also display in the player by default. It's likely you'll only need to follow the instructions in this section if you need captions for a video added to Kaltura before the date above, or if you'd rather not use Zoom’s captions (for entries that come from our Kaltura-Zoom integration).

A screenshot of the "Actions" menu.
  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video to which you want to add captions, and click the checkbox on the left side of that video's row (just to the left of the video thumbnail).
  3. Scroll to the top of the screen and click Actions, and select "Caption & Enrich."
  4. On the screen that appears, ensure that the following settings are selected:
    • Service: Machine
    • Source Media Language: English
    • Feature: Captions

A screenshot of the caption request screen, with the appropriate settings selected.

  1. Click "Submit." You'll see a notation with a blue background at the top of the screen that confirms that your request for captions has been received.

You won’t receive any confirmation after submitting that your captions have been completed and added, but you CAN tell by clicking on the video within "My Media" and looking at the preview of the video. If your captions have been added, you’ll see a small "CC" icon in the play bar at the bottom of the video preview.

A screenshot of the video player's control bar, circling the "CC" icon.

Another important thing to mention is that after adding captions to a video, an expandable box will now be below the video (at least when played in "My Media" or the Media Gallery), allowing students to view and download the transcript of the video as it plays. When the video is playing, the transcript will also highlight the text being spoken.

How to Edit Captions on Your Computer

If you're working on a long video (say, 30 minutes or more), it may be easier to download the captions onto your computer and edit them locally. Independent of the video's length, however, you may find this approach preferable to using the Closed Caption Editor in Canvas given the various affordances of working on a text editor (using find and replace functionality selectively, for example).


Here's the high-level overview of what you need to do in order to edit your captions locally, which will be described in more detail below:

  1. Download your caption file from Canvas.
  2. Edit it in a text editor on your computer.
  3. Upload it back into your video in Canvas.
  4. Delete the old inaccurate caption file.
  5. Delete any other unedited caption files (e.g. machine captions that came from Zoom).
  6. File away your caption file with the rest of your course files on your computer for safekeeping.


  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video in question and click the pencil icon on its row.
  3. Click the "Captions" tab below the video preview.
  4. On the row with your captions, click the icon with the downward arrow, and the caption file will download to your computer.

A screenshot of the options within the "Captions" tab.

  1. Open the caption file with a basic text editor. (Most operating systems have a free text editor that comes with them, such as WordPad in Windows or TextEdit on a Mac.)
  2. Now you can begin editing your captions. (See the drawer below for tips on how to edit your captions expeditiously.)

A screenshot of a text editor with captions in it next to a browser window in Canvas with the Kaltura video player.

  1. Once you've made all of your edits, save your file and return to Canvas in your browser.
  2. In the "Captions" tab in the video details, click the button labeled "Upload captions file."
  3. Browse for the file on your computer, select the language, leave the accuracy at 100%, and give it a label. The label is what will appear in the player when viewers select the captions they'd like displayed. You may want to add something like "(edited)" to the label to make clear to viewers (and perhaps your future self) that the captions have been checked for accuracy.
  4. If there are other caption files available that are inaccurate, consider deleting them or hiding them in the player.
  5. If you wish, store the edited caption file on your computer with the rest of the files related to your course for safekeeping.

Your edited captions will be visible immediately.

Human Captions

Note that because you can upload captions yourself, you can leverage captioning services that you employ on your own, such as or Cielo24. Captioning services like these usually cost between $1 and $2 per minute of media. You may want to talk to your department about this cost if you think it necessary.

How to Edit Captions Using the Closed Caption Editor

You can edit your captions within Canvas by using Kaltura's Closed Caption Editor.

  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video for which you want to edit captions, and click the pencil icon in its row.
  3. Click the "Captions" tab below the video preview.
  4. Click "Edit Captions." You'll be brought to the Closed Caption Editor.

A screenshot of the "Captions" menu, with the "Edit Captions" button circled.

Closed Caption Editor Functions

  • Editing text: Click on any row within the editor to edit the caption. When a row is clicked on, the video preview on the right side of the screen will jump to that part of the video. If you play the video preview, the captions will scroll automatically (unless you un-check the checkbox for "autoscroll").
  • Editing timecodes: If you wish, you can click on either a start or end timecode to edit it, which changes when the particular caption is displayed onscreen. (Generally speaking, this is generally not recommended due to the risk of overlapping timecodes.)
  • Adding speaker names: If you have multiple speakers, it can aid some viewers by identifying them in the captions. You have the option of adding a speaker's name to the beginning of a caption line by clicking the checkbox next to a caption's row and entering their name in in the field labeled "Add Speaker to selected items."
  • Finding and replacing words: Use the field next to the magnifying glass to find terms in your captions, and use the "replace with" field to replace all instances of that word with what you enter. This feature can save you some time if you use complex terminology, acronyms, proper nouns, or any other spoken words that the machine captioning system is repeatedly getting wrong.

Note that the >> symbol indicates that the system has detected a new speaker. Be sure to delete it if the speaker hasn't changed or to add it if the speaker has changed.

An annotated screenshot of the closed caption editor within Canvas.
  1. When you’re done making your edits, be sure to click the "Save" button at the top right of the screen.
  2. Confirm that you want to save by clicking "Yes." Any changes you made will be visible immediately in the player.
  3. Click "Back" at the top of the screen.
  4. Click "Captions" below the video preview.
  5. On the line with the captions you just edited, click the pencil icon.
  6. While you're welcome to edit the language and accuracy percentage, be sure to change the "label" of the video so that "auto-generated" is not part of it. (That is, you should make clear to your viewers that the captions have been edited for accuracy.) Appending "(edited)" should suffice.

Tip: Hide or Delete Unedited Machine Captions

If you take the time to edit your captions, it makes sense that unedited captions shouldn't be an option for viewers. Take an extra moment to either hide unedited captions from viewers or delete them outright.

Tip: Save Frequently

Save your work frequently in the Closed Caption Editor within Canvas. Your session may time out, and unless you've saved your edits, they may be lost.

How to Hide Captions From Viewers (But Not Delete Them)

If you've edited your captions, you probably don't want your viewers to have the option to select unedited captions. Luckily, hiding your captions involves fairly few clicks, although admittedly the combination of Kaltura's iconography and tooltip (that appears when you hover your mouse over the icon) make it a tad confusing.

  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video in question and click the pencil icon on its row.
  3. Click the "Captions" tab underneath the video player.
  4. You should now see the list of captions affiliated with your video. Here you’ll want to make sure the correct captions are displaying in the player. You’re looking for a small icon that looks like a screen with a play button in it. If it has a slash through it, that means that the caption file in its row will NOT offer these captions as an option. If the icon is the wrong one for the selected caption file, just click it.

An annotated screenshot of a list of captions, with the "hide/show" column circled.

How to Delete Captions

Don't Delete Your Only Set of Captions

Captions are required in all educational videos to meet accessibility requirements. We strongly recommend against deleting your captions so that none are available, even if they're inaccurate.

If you need to delete one of your caption files from your Kaltura video, follow the steps below.

  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video in question and click the pencil icon on its row.
  3. Click the "Captions" tab underneath the video player.
  4. You should now see the list of captions affiliated with your video. Click the "X" on the row of the caption you want to delete.

An annotated screenshot of a list of captions, with the "delete" column circled.

How to Allow Others to Edit Your Captions

Though we cover how to do this indirectly in our documentation on sharing videos, it's worth dropping the instructions on this page as well. The unfortunate truth is that editing captions is time-consuming. It might take you 3-4 times the length of the video. So getting some help in editing your videos' captions might be essential.

  1. Within Canvas, click "My Media" in the left navigation.
  2. Locate the video in question and click the pencil icon on its row.
  3. Click the "Collaboration" tab under the video player.
  4. Click the "Add Collaborator" button that appears.
  5. Search for the user in question (using their UCSD username is best rather than their first/last name), and click on it once you find it in the search results.
  6. Check the box for co-editor.
  7. Click "Add."
This user can now edit your captions. Be aware that they can also edit just about anything else about your video, too - the only things they can't do is delete it, publish it, or add other collaborators.

Caption Editing Tips

There’s no doubt that editing your captions takes some time. Below are some tips about how to make the process as efficient as possible while ensuring accuracy and accessibility. Click any of the links below to jump to a more detailed explanation.

First review the captions without playing the video

Many of the errors that are made by machine captioning have to do with mistakenly assuming there's a new speaker, misspellings, and grammatical errors. These can be fixed without playing the video and won't have you constantly stopping and starting the video. And if you were the one in the video, there’s a good chance that you know what was said anyway.

Leverage media player speed controls

Playing a video more quickly or slowly can serve you well when you’re editing your captions. The Kaltura video player, for example, offers you the ability to change the speed of the playback by clicking the "1x" button in the player controls. Consider lowering the speed of playback to make it easier to edit without having to pause as frequently. Alternatively, if you’re finding the captions to be more accurate than expected, speed the video up.

Leverage peripheral devices with play/pause buttons

If you have headphones, a keyboard, or any other devices with a play/pause button, you can leverage those buttons to your advantage while editing your captions.

Be aware of speaker changes (or lack thereof)

At minimum, a change in speaker should be denoted with >> in the captions. Ideally, instead use square brackets and enter the speaker’s name (e.g. [John Smith]).

For whatever reason, machine captions often mistakenly detect a change in speaker, and as a result, your captions may be littered with >> characters. If there wasn’t a change in speaker, delete the characters.

Pay for human captioning (optional)

Because you can upload captions yourself, you can leverage captioning services that you employ on your own, such as or Cielo24. Captioning services like these usually cost between $1 and $2 per minute of media. (That is, a 5-minute video would cost between $5 and $10.) Take note, however, that all captions uploaded to Canvas must be in .srt format.

Frequently Asked Questions (FAQs)

Use the list below to jump to the answer.

What are my responsibilities regarding captioning?

Answer: All of your videos must at least contain machine captions, at the very least.

As stated above, all videos added to "My Media" after 13 June 2020 will automatically have captions requested and inserted into the video. However, machine captions are only about 70% accurate for colloquial speech. With potentially 1 out of every 3 words being inaccurate, we strongly encourage instructors to consider editing their captions for accuracy.

There’s no doubt that editing captions is time-consuming, particularly for longer videos. With that in mind, we encourage you to reach out to TAs and student workers for assistance in the process. Note that you can add a student as a collaborator on a video (specifically a "co-editor") and they’ll be able to follow the instructions on this page to edit your video’s captions. You can learn more about adding collaborators in our tutorial on sharing videos.

If a student with a disability requires captioning as an accommodation, captions will be provided in real time by a certified captionist or you may be asked to provide a complete and accurate captioned transcription of the video. Please contact the Office for Students with Disabilities at if you have further questions about disability accommodations.

How long does it take to generate the captions? What’s the turnaround time?

Answer: up to 2 times the length of the video.

As you might imagine, the time it takes for your captions to be created depends on the length of your media. The formula that dictates how long it will take machine captions to be generated is roughly as follows:

  • For entries shorter than 15 minutes, the machine caption turnaround time should be less than 30 minutes after the video is done processing.
  • For entries longer than 15 minutes, the machine caption turnaround time should be no more than 2 times the length of the video after the video is done processing.

How do I let someone else edit my captions?

Answer: Add them as a collaborator on the video, specifically a "co-editor."

Follow our instructions on adding collaborators to a video to add a user as a "co-editor" on your video. The video will then show up in their that user's "My Media," after which time they can follow the instructions on this page to edit your captions. Note that that user will also be able to perform a variety of other edits to your video, such as renaming it, changing the description, changing the thumbnail, etc. They’ll also be able to download your video.

What happens to my captions if I edit a video?

Answer: If you click "save" your old captions will be cut at the timecodes you identify. If you click "save a copy" after editing, your "old" captions will be present (cut appropriately) AND a new set of machine captions will be requested.

If you make cuts to a video, the captions will be cut at the timecodes you identify. BUT, every new entry created in Kaltura automatically has machine captions requested. This means:

  • For videos where you click "save" after making your edits, your captions will be cut at the timecodes you identify. You may want to take a look at the captions around those timecodes, however, just to make sure that they look right. You can make edits to the captions if necessary.
  • For videos where you click "save a copy" after making your edits, the captions will be cut up just like the video. However, because all new Kaltura entries automatically have machine captions requested and inserted, a new set of captions will eventually show up. You may want to either hide or delete one set of the captions.
Need additional help with videos? Contact the Multimedia Services team at