Subtitles provide context and clarity to video content. Publishers on Twitter have long advocated for the ability to provide this context to their audiences through the use of subtitles, particularly in sound-off scenarios. Videos in the Twitter timeline autoplay with the sound off, which is why we’re excited to announce the support of .SRT subtitle display on web, iOS, and Android.
Subtitles, as we’re defining them, are transcripts of a video’s dialogue or audio contained in .SRT files that are attached to videos through either Media Studio, ads.twitter.com, or via API. Subtitles differ from closed captions that are meant to provide better accessibility for hearing impaired users, though you may often hear them mentioned interchangeably.
Until recently, Twitter has supported CEA-style captions in a limited capacity that are enabled when a user has turned on closed captioning through the accessibility settings on their Android or iOS devices. This isn’t changing, and these will appear in the same fashion.
If the video you're watching has subtitles, you'll be able to see them on iOS and Android if your device's sound is turned off, or on web by clicking on the "cc" toggle. By default, the subtitles will hide when the video is expanded, as this action enables sound playback.