third_party/fuchsia-sdk/fidl/fuchsia.media.audio/volume_control.fidl

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.media.audio;

/// The volume value representing the maximum loudness.
const float32 MAX_VOLUME = 1.0;

/// The volume value representing silence.
const float32 MIN_VOLUME = 0.0;

/// A protocol for controlling volume.
protocol VolumeControl {
    /// Sets the volume of the audio element to the given value in
    /// [0.0, 1.0]. If the value is provided is outside of [0.0, 1.0],
    /// the value is clamped before application.
    SetVolume(float32 volume);
    /// Sets whether the controlled element is muted. Mute is not the same
    /// as setting volume to 0.0; volume will persist for the duration of
    /// a mute. If volume was 0.5 before mute, volume will resume at 0.5
    /// following unmute.
    SetMute(bool mute);

    /// Emitted when the volume or mute state of the audio element changes.
    -> OnVolumeMuteChanged(float32 new_volume, bool new_muted);
};