withMatchingAudio

What the player chooses by itself when the audio is in one of preferredLanguages, a language the viewer reads and so understands (#506), as mpv's subs-with-matching-audio. MatchingAudioSubtitles.All chooses as ever, so a viewer who prefers English subtitles keeps them under English audio, which is mpv's default too. A viewer who wants subtitles only for what they do not understand asks for MatchingAudioSubtitles.ForcedOnly, and gets the signs and foreign lines a forced track carries and no more. The choice is made again at each audio change, and a subtitle chosen by hand is never held back.