MediaSyncEvent.java revision 505e5c8859f596ed58489be565d6e029314b2ac8 
1/*
2 * Copyright (C) 2012 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.media;
18
19/**
20 * The MediaSyncEvent class defines events that can be used to synchronize playback or capture
21 * actions between different players and recorders.
22 * <p>For instance, {@link AudioRecord#startRecording(MediaSyncEvent)} is used to start capture
23 * only when the playback on a particular audio session is complete.
24 * The audio session ID is retrieved from a player (e.g {@link MediaPlayer}, {@link AudioTrack} or
25 * {@link ToneGenerator}) by use of the getAudioSessionId() method.
26 * @hide
27 */
28public class MediaSyncEvent {
29
30    /**
31     * No sync event specified. When used with a synchronized playback or capture method, the
32     * behavior is equivalent to calling the corresponding non synchronized method.
33     */
34    public static final int SYNC_EVENT_NONE = AudioSystem.SYNC_EVENT_NONE;
35
36    /**
37     * The corresponding action is triggered only when the presentation is completed
38     * (meaning the media has been presented to the user) on the specified session.
39     * A synchronization of this type requires a source audio session ID to be set via
40     * {@link #setAudioSessionId(int) method.
41     */
42    public static final int SYNC_EVENT_PRESENTATION_COMPLETE =
43                                                    AudioSystem.SYNC_EVENT_PRESENTATION_COMPLETE;
44
45
46    /**
47     * Creates a synchronization event of the sepcified type.
48     *
49     * <p>The type specifies which kind of event is monitored.
50     * For instance, event {@link #SYNC_EVENT_PRESENTATION_COMPLETE} corresponds to the audio being
51     * presented to the user on a particular audio session.
52     * @param type the synchronization event type.
53     * @return the MediaSyncEvent created.
54     * @throws java.lang.IllegalArgumentException
55     */
56    public static MediaSyncEvent createEvent(int eventType)
57                            throws IllegalArgumentException {
58        if (!isValidType(eventType)) {
59            throw (new IllegalArgumentException(eventType
60                    + "is not a valid MediaSyncEvent type."));
61        } else {
62            return new MediaSyncEvent(eventType);
63        }
64    }
65
66    private final int mType;
67    private int mAudioSession = 0;
68
69    private MediaSyncEvent(int eventType) {
70        mType = eventType;
71    }
72
73    /**
74     * Sets the event source audio session ID.
75     *
76     * <p>The audio session ID specifies on which audio session the synchronization event should be
77     * monitored.
78     * It is mandatory for certain event types (e.g. {@link #SYNC_EVENT_PRESENTATION_COMPLETE}).
79     * For instance, the audio session ID can be retrieved via
80     * {@link MediaPlayer#getAudioSessionId()} when monitoring an event on a particular MediaPlayer.
81     * @param audioSessionId the audio session ID of the event source being monitored.
82     * @return the MediaSyncEvent the method is called on.
83     * @throws java.lang.IllegalArgumentException
84     */
85    public MediaSyncEvent setAudioSessionId(int audioSessionId)
86            throws IllegalArgumentException {
87        if (audioSessionId > 0) {
88            mAudioSession = audioSessionId;
89        } else {
90            throw (new IllegalArgumentException(audioSessionId + " is not a valid session ID."));
91        }
92        return this;
93    }
94
95    /**
96     * Gets the synchronization event type.
97     *
98     * @return the synchronization event type.
99     */
100    public int getType() {
101        return mType;
102    }
103
104    /**
105     * Gets the synchronization event audio session ID.
106     *
107     * @return the synchronization audio session ID. The returned audio session ID is 0 if it has
108     * not been set.
109     */
110    public int getAudioSessionId() {
111        return mAudioSession;
112    }
113
114    private static boolean isValidType(int type) {
115        switch (type) {
116        case SYNC_EVENT_NONE:
117        case SYNC_EVENT_PRESENTATION_COMPLETE:
118            return true;
119        default:
120            return false;
121        }
122    }
123}
124