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/*
* Copyright (C) 2016 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 com.android.tv.util;
import java.util.concurrent.TimeUnit;
/**
* A class that includes convenience methods for time shift plays.
*/
public class TimeShiftUtils {
private static final String TAG = "TimeShiftUtils";
private static final boolean DEBUG = false;
private static final long SHORT_PROGRAM_THRESHOLD_MILLIS = TimeUnit.MINUTES.toMillis(46);
private static final int[] SHORT_PROGRAM_SPEED_FACTORS = new int[] {2, 4, 12, 48};
private static final int[] LONG_PROGRAM_SPEED_FACTORS = new int[] {2, 8, 32, 128};
/**
* The maximum play speed level support by time shift play. In other words, the valid
* speed levels are ranged from 0 to MAX_SPEED_LEVEL (included).
*/
public static final int MAX_SPEED_LEVEL = SHORT_PROGRAM_SPEED_FACTORS.length - 1;
/**
* Returns real speeds used in time shift play. This method is only for fast-forwarding and
* rewinding. The normal play speed is not addressed here.
*
* @param speedLevel the valid value is ranged from 0 to {@link #MAX_SPEED_LEVEL}.
* @param programDurationMillis the length of program under playing.
* @throws IndexOutOfBoundsException if speed level is out of its range.
*/
public static int getPlaybackSpeed(int speedLevel, long programDurationMillis)
throws IndexOutOfBoundsException {
return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) ?
LONG_PROGRAM_SPEED_FACTORS[speedLevel] : SHORT_PROGRAM_SPEED_FACTORS[speedLevel];
}
/**
* Returns the maxium possible play speed according to the program's length.
* @param programDurationMillis the length of program under playing.
*/
public static int getMaxPlaybackSpeed(long programDurationMillis) {
return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) ?
LONG_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL]
: SHORT_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL];
}
}
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