replayGain

Whether to honour the loudness the encoder measured, and which measurement to use.

Off by default: a player changing the level of what it was given, unasked, is a surprise. Turn it on and a quiet album stops playing quiet without the listener touching the volume. The gain is clamped by the file's own peak so it can never clip. A tag without a peak, which is every Opus tag, can lower the level but never raise it, and volumeCeiling does not widen the clamp. See ReplayGainMode.