1/*
2 * Copyright 2015 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 * An immutable object that represents the linear correlation between the media time
21 * and the system time. It contains the media clock rate, together with the media timestamp
22 * of an anchor frame and the system time when that frame was presented or is committed
23 * to be presented.
24 * <p>
25 * The phrase "present" means that audio/video produced on device is detectable by an external
26 * observer off device.
27 * The time is based on the implementation's best effort, using whatever knowledge
28 * is available to the system, but cannot account for any delay unknown to the implementation.
29 * The anchor frame could be any frame, including a just-rendered frame, or even a theoretical
30 * or in-between frame, based on the source of the MediaTimestamp.
31 * When the anchor frame is a just-rendered one, the media time stands for
32 * current position of the playback or recording.
33 *
34 * @see MediaSync#getTimestamp
35 * @see MediaPlayer#getTimestamp
36 */
37public final class MediaTimestamp
38{
39    /**
40     * Get the media time of the anchor in microseconds.
41     */
42    public long getAnchorMediaTimeUs() {
43        return mediaTimeUs;
44    }
45
46    /**
47     * Get the {@link java.lang.System#nanoTime system time} corresponding to the media time
48     * in nanoseconds.
49     */
50    public long getAnchorSytemNanoTime() {
51        return nanoTime;
52    }
53
54    /**
55     * Get the rate of the media clock in relation to the system time.
56     * <p>
57     * It is 1.0 if media clock advances in sync with the system clock;
58     * greater than 1.0 if media clock is faster than the system clock;
59     * less than 1.0 if media clock is slower than the system clock.
60     */
61    public float getMediaClockRate() {
62        return clockRate;
63    }
64
65    /** @hide - accessor shorthand */
66    public final long mediaTimeUs;
67    /** @hide - accessor shorthand */
68    public final long nanoTime;
69    /** @hide - accessor shorthand */
70    public final float clockRate;
71
72    /** @hide */
73    MediaTimestamp(long mediaUs, long systemNs, float rate) {
74        mediaTimeUs = mediaUs;
75        nanoTime = systemNs;
76        clockRate = rate;
77    }
78
79    /** @hide */
80    MediaTimestamp() {
81        mediaTimeUs = 0;
82        nanoTime = 0;
83        clockRate = 1.0f;
84    }
85}
86