Live captions

YouTube produces them from the incoming audio as the stream goes out. Expect a lag of a few seconds, and accuracy that falls away with crosstalk, poor sound or music underneath. They only work on normal latency streams, so anything set to low or ultra-low latency, including most mobile broadcasts, cannot use them. The automatic version is English only. Broadcasters who need better can push their own caption track from third-party software into the caption ingest URL. One detail catches people out: live captions disappear when the stream ends, and the archive gets a fresh set generated the ordinary way, which will read differently.