The accessibility team at Facebook has developed a method for generating automatic captioning of your Facebook videos. You can utilize this function at the time you upload the video, or you can add captions to an existing video. Currently, automatic captions are only generated in U.S. English, but you can upload your own custom made captions in the language of your choice. If the viewer has audio turned off, captions will appear automatically, otherwise, they will need to enable captions.
From Facebook
You can add captions to your Page’s video to make it accessible to a broader audience. You can either automatically generate captions and edit them, or you can upload a SubRip (.srt) file.
Once your video has been published, click Generate from the banner at the top of your post
Edit the captions and click Save to Video
Note: Generating captions for videos is currently only available in US English.
Add Captions to Your Page’s Video With a SubRip (.srt) File:
Make sure that your caption files are correctly named and formatted before you upload them.
If you select a default language, captions will appear in this language when a viewer’s preferred language isn’t available.
To add captions to an existing video on your Page, find the post on your Page’s Timeline, click in the top-right corner, select Edit Post and follow the steps above.
Note: People who watch your Page’s video with sound turned off will automatically see captions. People who watch your video with sound turned on will need to turn on captions to see them. The language people see captions in is determined by their preferred language.
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