pub trait GainControlProxyInterface: Send + Sync {
    // Required methods
    fn set_gain(&self, gain_db: f32) -> Result<(), Error>;
    fn set_gain_with_ramp(
        &self,
        gain_db: f32,
        duration: i64,
        ramp_type: RampType,
    ) -> Result<(), Error>;
    fn set_mute(&self, muted: bool) -> Result<(), Error>;
}