You can easily create and upload caption files when you add video content in the New Rich Content Editor. The New Rich Content Editor is used in features that support the editor (Announcements, Assignments, Discussions, Pages, and Quizzes).
This lesson only applies to creating captions for videos created in or uploaded into Canvas. If you've created a video outside of Canvas that you want to share in your course, you can create captions using an external captioning tool such as Amara or YouTube.
Note: Users can view video captions in the Canvas apps. However, iOS devices can only display captions in WebVTT format. If you use another format besides WebVTT, users on iOS devices will not be able to display the video captions.
Open Media Uploader
In the New Rich Content Editor, click the Media icon . Then select the Upload/Record Media option .
Note: To view the Media icon, you may need to click the Options icon .
You can upload a media file in the Computer tab.
You can also record media using the New Rich Content Editor in the Record tab.
Select Language and FIle
To specify the language for your captions, click the Select Language drop-down .
To attach your caption file, click the Choose caption file button . You can upload SRT or VTT files.
View your media file  and your caption file . To attach additional caption files, click the Add button .
When finished adding media and caption files, click the Submit button .
When you add captions to a media file, the file displays a CC button.