1 /* 2 * Copyright (C) 2016 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.util; 18 19 import java.util.concurrent.TimeUnit; 20 21 /** A class that includes convenience methods for time shift plays. */ 22 public class TimeShiftUtils { 23 private static final String TAG = "TimeShiftUtils"; 24 private static final boolean DEBUG = false; 25 26 private static final long SHORT_PROGRAM_THRESHOLD_MILLIS = TimeUnit.MINUTES.toMillis(46); 27 private static final int[] SHORT_PROGRAM_SPEED_FACTORS = new int[] {2, 4, 12, 48}; 28 private static final int[] LONG_PROGRAM_SPEED_FACTORS = new int[] {2, 8, 32, 128}; 29 30 /** 31 * The maximum play speed level support by time shift play. In other words, the valid speed 32 * levels are ranged from 0 to MAX_SPEED_LEVEL (included). 33 */ 34 public static final int MAX_SPEED_LEVEL = SHORT_PROGRAM_SPEED_FACTORS.length - 1; 35 36 /** 37 * Returns real speeds used in time shift play. This method is only for fast-forwarding and 38 * rewinding. The normal play speed is not addressed here. 39 * 40 * @param speedLevel the valid value is ranged from 0 to {@link #MAX_SPEED_LEVEL}. 41 * @param programDurationMillis the length of program under playing. 42 * @throws IndexOutOfBoundsException if speed level is out of its range. 43 */ 44 public static int getPlaybackSpeed(int speedLevel, long programDurationMillis) 45 throws IndexOutOfBoundsException { 46 return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) 47 ? LONG_PROGRAM_SPEED_FACTORS[speedLevel] 48 : SHORT_PROGRAM_SPEED_FACTORS[speedLevel]; 49 } 50 51 /** 52 * Returns the maxium possible play speed according to the program's length. 53 * 54 * @param programDurationMillis the length of program under playing. 55 */ 56 public static int getMaxPlaybackSpeed(long programDurationMillis) { 57 return (programDurationMillis > SHORT_PROGRAM_THRESHOLD_MILLIS) 58 ? LONG_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL] 59 : SHORT_PROGRAM_SPEED_FACTORS[MAX_SPEED_LEVEL]; 60 } 61 } 62
