Virtual Chorister app for iPhone and iPad
Virtual Chorister assists musicians participating in virtual collaboration projects (its great for singers AND instrumentalists).
Normally, you must watch a conductor video on a separate device while recording your own performance video. Virtual Chorister lets you watch a video on your iPhone (or iPad) while recording your own, in either portrait or landscape orientation.
Guide videos can be loaded from Photos, Files, or streamed from YouTube. Recorded videos are saved to your Photo Library.