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