https://source.android.com/ 
/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.media;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

import android.annotation.IntDef;


Structure that groups a position in frame units relative to an assumed audio stream,
together with the estimated time when that frame enters or leaves the audio
processing pipeline on that device. This can be used to coordinate events
and interactions with the external environment.


The time is based on the implementation's best effort, using whatever knowledge
is available to the system, but cannot account for any delay unknown to the implementation.

See Also:
/**
 * Structure that groups a position in frame units relative to an assumed audio stream,
 * together with the estimated time when that frame enters or leaves the audio
 * processing pipeline on that device. This can be used to coordinate events
 * and interactions with the external environment.
 * <p>
 * The time is based on the implementation's best effort, using whatever knowledge
 * is available to the system, but cannot account for any delay unknown to the implementation.
 *
 * @see AudioTrack#getTimestamp AudioTrack.getTimestamp(AudioTimestamp)
 * @see AudioRecord#getTimestamp AudioRecord.getTimestamp(AudioTimestamp, int)
 */
public final class AudioTimestamp
{
    
Clock monotonic or its equivalent on the system, in the same units and timebase as System.nanoTime. 
/**
     * Clock monotonic or its equivalent on the system,
     * in the same units and timebase as {@link java.lang.System#nanoTime}.
     */
    public static final int TIMEBASE_MONOTONIC = 0;

    
Clock monotonic including suspend time or its equivalent on the system, in the same units and timebase as SystemClock.elapsedRealtimeNanos. 
/**
     * Clock monotonic including suspend time or its equivalent on the system,
     * in the same units and timebase as {@link android.os.SystemClock#elapsedRealtimeNanos}.
     */
    public static final int TIMEBASE_BOOTTIME = 1;

    
@hide
/** @hide */
    @IntDef({
        TIMEBASE_MONOTONIC,
        TIMEBASE_BOOTTIME,
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface Timebase {}

    
Position in frames relative to start of an assumed audio stream.

 When obtained through AudioRecord.getTimestamp(AudioTimestamp, int), all 64 bits of position are valid. 
 When obtained through AudioTrack.getTimestamp(AudioTimestamp), the low-order 32 bits of position is in wrapping frame units similar to AudioTrack.getPlaybackHeadPosition(). 
/**
     * Position in frames relative to start of an assumed audio stream.
     * <p>
     * When obtained through
     * {@link AudioRecord#getTimestamp AudioRecord.getTimestamp(AudioTimestamp, int)},
     * all 64 bits of position are valid.
     * <p>
     * When obtained through
     * {@link AudioTrack#getTimestamp AudioTrack.getTimestamp(AudioTimestamp)},
     * the low-order 32 bits of position is in wrapping frame units similar to
     * {@link AudioTrack#getPlaybackHeadPosition AudioTrack.getPlaybackHeadPosition()}.
     */
    public long framePosition;

    
Time associated with the frame in the audio pipeline.

 When obtained through AudioRecord.getTimestamp(AudioTimestamp, int), this is the estimated time in nanoseconds when the frame referred to by framePosition was captured. The timebase is either TIMEBASE_MONOTONIC or TIMEBASE_BOOTTIME, depending on the timebase parameter used in AudioRecord.getTimestamp(AudioTimestamp, int). 
 When obtained through AudioTrack.getTimestamp(AudioTimestamp), this is the estimated time when the frame was presented or is committed to be presented, with a timebase of TIMEBASE_MONOTONIC. 
/**
     * Time associated with the frame in the audio pipeline.
     * <p>
     * When obtained through
     * {@link AudioRecord#getTimestamp AudioRecord.getTimestamp(AudioTimestamp, int)},
     * this is the estimated time in nanoseconds when the frame referred to by
     * {@link #framePosition} was captured. The timebase is either
     * {@link #TIMEBASE_MONOTONIC} or {@link #TIMEBASE_BOOTTIME}, depending
     * on the timebase parameter used in
     * {@link AudioRecord#getTimestamp AudioRecord.getTimestamp(AudioTimestamp, int)}.
     * <p>
     * When obtained through
     * {@link AudioTrack#getTimestamp AudioTrack.getTimestamp(AudioTimestamp)},
     * this is the estimated time when the frame was presented or is committed to be presented,
     * with a timebase of {@link #TIMEBASE_MONOTONIC}.
     */
    public long nanoTime;
}