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 17 package 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 */ 37 public final class MediaTimestamp 38 { 39 /** 40 * An unknown media timestamp value 41 */ 42 public static final MediaTimestamp TIMESTAMP_UNKNOWN = new MediaTimestamp(-1, -1, 0.0f); 43 44 /** 45 * Get the media time of the anchor in microseconds. 46 */ getAnchorMediaTimeUs()47 public long getAnchorMediaTimeUs() { 48 return mediaTimeUs; 49 } 50 51 /** 52 * Get the {@link java.lang.System#nanoTime system time} corresponding to the media time 53 * in nanoseconds. 54 */ getAnchorSytemNanoTime()55 public long getAnchorSytemNanoTime() { 56 return nanoTime; 57 } 58 59 /** 60 * Get the rate of the media clock in relation to the system time. 61 * <p> 62 * It is 1.0 if media clock advances in sync with the system clock; 63 * greater than 1.0 if media clock is faster than the system clock; 64 * less than 1.0 if media clock is slower than the system clock. 65 */ getMediaClockRate()66 public float getMediaClockRate() { 67 return clockRate; 68 } 69 70 /** @hide - accessor shorthand */ 71 public final long mediaTimeUs; 72 /** @hide - accessor shorthand */ 73 public final long nanoTime; 74 /** @hide - accessor shorthand */ 75 public final float clockRate; 76 77 /** @hide */ MediaTimestamp(long mediaUs, long systemNs, float rate)78 MediaTimestamp(long mediaUs, long systemNs, float rate) { 79 mediaTimeUs = mediaUs; 80 nanoTime = systemNs; 81 clockRate = rate; 82 } 83 84 /** @hide */ MediaTimestamp()85 MediaTimestamp() { 86 mediaTimeUs = 0; 87 nanoTime = 0; 88 clockRate = 1.0f; 89 } 90 91 @Override equals(Object obj)92 public boolean equals(Object obj) { 93 if (this == obj) return true; 94 if (obj == null || getClass() != obj.getClass()) return false; 95 96 final MediaTimestamp that = (MediaTimestamp) obj; 97 return (this.mediaTimeUs == that.mediaTimeUs) 98 && (this.nanoTime == that.nanoTime) 99 && (this.clockRate == that.clockRate); 100 } 101 102 @Override toString()103 public String toString() { 104 return getClass().getName() 105 + "{AnchorMediaTimeUs=" + mediaTimeUs 106 + " AnchorSystemNanoTime=" + nanoTime 107 + " clockRate=" + clockRate 108 + "}"; 109 } 110 } 111