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      1 /*
      2  * Copyright (C) 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 com.android.tv.tuner.exoplayer.audio;
     18 
     19 import com.android.tv.common.SoftPreconditions;
     20 
     21 import android.os.SystemClock;
     22 
     23 /**
     24  * Copy of {@link com.google.android.exoplayer.MediaClock}.
     25  * <p>
     26  * A simple clock for tracking the progression of media time. The clock can be started, stopped and
     27  * its time can be set and retrieved. When started, this clock is based on
     28  * {@link SystemClock#elapsedRealtime()}.
     29  */
     30 /* package */ class AudioClock {
     31     private boolean mStarted;
     32 
     33     /**
     34      * The media time when the clock was last set or stopped.
     35      */
     36     private long mPositionUs;
     37 
     38     /**
     39      * The difference between {@link SystemClock#elapsedRealtime()} and {@link #mPositionUs}
     40      * when the clock was last set or mStarted.
     41      */
     42     private long mDeltaUs;
     43 
     44     private float mPlaybackSpeed = 1.0f;
     45     private long mDeltaUpdatedTimeUs;
     46 
     47     /**
     48      * Starts the clock. Does nothing if the clock is already started.
     49      */
     50     public void start() {
     51         if (!mStarted) {
     52             mStarted = true;
     53             mDeltaUs = elapsedRealtimeMinus(mPositionUs);
     54             mDeltaUpdatedTimeUs = SystemClock.elapsedRealtime() * 1000;
     55         }
     56     }
     57 
     58     /**
     59      * Stops the clock. Does nothing if the clock is already stopped.
     60      */
     61     public void stop() {
     62         if (mStarted) {
     63             mPositionUs = elapsedRealtimeMinus(mDeltaUs);
     64             mStarted = false;
     65         }
     66     }
     67 
     68     /**
     69      * @param timeUs The position to set in microseconds.
     70      */
     71     public void setPositionUs(long timeUs) {
     72         this.mPositionUs = timeUs;
     73         mDeltaUs = elapsedRealtimeMinus(timeUs);
     74         mDeltaUpdatedTimeUs = SystemClock.elapsedRealtime() * 1000;
     75     }
     76 
     77     /**
     78      * @return The current position in microseconds.
     79      */
     80     public long getPositionUs() {
     81         if (!mStarted) {
     82             return mPositionUs;
     83         }
     84         if (mPlaybackSpeed != 1.0f) {
     85             long elapsedTimeFromPlaybackSpeedChanged = SystemClock.elapsedRealtime() * 1000
     86                     - mDeltaUpdatedTimeUs;
     87             return elapsedRealtimeMinus(mDeltaUs)
     88                     + (long) ((mPlaybackSpeed - 1.0f) * elapsedTimeFromPlaybackSpeedChanged);
     89         } else {
     90             return elapsedRealtimeMinus(mDeltaUs);
     91         }
     92     }
     93 
     94     /**
     95      * Sets playback speed. {@code speed} should be positive.
     96      */
     97     public void setPlaybackSpeed(float speed) {
     98         SoftPreconditions.checkState(speed > 0);
     99         mDeltaUs = elapsedRealtimeMinus(getPositionUs());
    100         mDeltaUpdatedTimeUs = SystemClock.elapsedRealtime() * 1000;
    101         mPlaybackSpeed = speed;
    102     }
    103 
    104     private long elapsedRealtimeMinus(long toSubtractUs) {
    105         return SystemClock.elapsedRealtime() * 1000 - toSubtractUs;
    106     }
    107 }
    108