Important terminology note: The earlier version of Stream will now be known as Microsoft Stream (Classic) https://web.microsoftstream.com/ and the new version will be referred to as Microsoft Stream (on SharePoint) https://stream.office.com to clarify the differences moving forward.
If a video's Language field is set to a supported language, Stream can automatically generate captions using Automatic Speech Recognition technology.
Captions are used in three ways:
Upload a video for which you want to enable auto-generated captions. If the video is already uploaded, go to the Edit video page.
In the Details section, select a supported language.
On the Options tab, set Auto-generate captions to On. (Note: This setting won't be available if you have selected a non-supported language.)
Stream will automatically begin generating captions.
To upload a caption file, follow the steps in Add subtitles and captions.
You can't upload a caption file if you have set Autogenerate captions to On. To upload a caption file, set this to Off.
It typically takes 1-2x the video's duration, so for example, for a one hour video, expect to wait approximately two hours to finish processing.