1/*
2 * Copyright (C) 2020 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.hardware.automotive.audiocontrol@2.0;
18
19import ICloseHandle;
20import IFocusListener;
21import android.hardware.audio.common@6.0::AudioUsage;
22
23/**
24 * Interacts with the car's audio subsystem to manage audio sources and volumes
25 */
26interface IAudioControl {
27    /**
28     * Registers focus listener to be used by HAL for requesting and abandoning audio focus.
29     *
30     * It is expected that there will only ever be a single focus listener registered. If the
31     * observer dies, the HAL implementation must unregister observer automatically. If called when
32     * a listener is already registered, the existing one should be unregistered and replaced with
33     * the new listener.
34     *
35     * @param listener the listener interface
36     * @return closeHandle A handle to unregister observer.
37     */
38    registerFocusListener(IFocusListener listener) generates (ICloseHandle closeHandle);
39
40    /**
41     * Notifies HAL of changes in audio focus status for focuses requested or abandoned by the HAL.
42     *
43     * This will be called in response to IFocusListener's requestAudioFocus and
44     * abandonAudioFocus, as well as part of any change in focus being held by the HAL due focus
45     * request from other activities or services.
46     *
47     * The HAL is not required to wait for an callback of AUDIOFOCUS_GAIN before playing audio, nor
48     * is it required to stop playing audio in the event of a AUDIOFOCUS_LOSS callback is received.
49     *
50     * @param usage The audio usage associated with the focus change {@code AttributeUsage}
51     * @param zoneId The identifier for the audio zone that the HAL is playing the stream in
52     * @param focusChange the AudioFocusChange that has occurred
53     */
54    oneway onAudioFocusChange(bitfield<AudioUsage> usage, int32_t zoneId,
55        bitfield<AudioFocusChange> focusChange);
56
57    /**
58     * Control the right/left balance setting of the car speakers.
59     *
60     * This is intended to shift the speaker volume toward the right (+) or left (-) side of
61     * the car. 0.0 means "centered". +1.0 means fully right. -1.0 means fully left.
62     *
63     * A value outside the range -1 to 1 must be clamped by the implementation to the -1 to 1
64     * range.
65     */
66    oneway setBalanceTowardRight(float value);
67
68    /**
69     * Control the fore/aft fade setting of the car speakers.
70     *
71     * This is intended to shift the speaker volume toward the front (+) or back (-) of the car.
72     * 0.0 means "centered". +1.0 means fully forward. -1.0 means fully rearward.
73     *
74     * A value outside the range -1 to 1 must be clamped by the implementation to the -1 to 1
75     * range.
76     */
77    oneway setFadeTowardFront(float value);
78};
79