Complex sentence: It has been claimed that this album is not a live album but a studio recording with audience noise added to it, that claim is false, it is Slayer playing live to a small audience in a studio as the venue.
Split into simpler sentences: It has been claimed that this album is not a live album but a studio recording with audience noise added to it. That claim is false, it is Slayer playing live to a small audience in a studio as the venue.