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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 package com.google.android.exoplayer2.extractor;
17 
18 import androidx.annotation.Nullable;
19 import com.google.android.exoplayer2.C;
20 import com.google.android.exoplayer2.util.Assertions;
21 
22 /**
23  * Maps seek positions (in microseconds) to corresponding positions (byte offsets) in the stream.
24  */
25 public interface SeekMap {
26 
27   /** A {@link SeekMap} that does not support seeking. */
28   class Unseekable implements SeekMap {
29 
30     private final long durationUs;
31     private final SeekPoints startSeekPoints;
32 
33     /**
34      * @param durationUs The duration of the stream in microseconds, or {@link C#TIME_UNSET} if the
35      *     duration is unknown.
36      */
Unseekable(long durationUs)37     public Unseekable(long durationUs) {
38       this(durationUs, 0);
39     }
40 
41     /**
42      * @param durationUs The duration of the stream in microseconds, or {@link C#TIME_UNSET} if the
43      *     duration is unknown.
44      * @param startPosition The position (byte offset) of the start of the media.
45      */
Unseekable(long durationUs, long startPosition)46     public Unseekable(long durationUs, long startPosition) {
47       this.durationUs = durationUs;
48       startSeekPoints =
49           new SeekPoints(startPosition == 0 ? SeekPoint.START : new SeekPoint(0, startPosition));
50     }
51 
52     @Override
isSeekable()53     public boolean isSeekable() {
54       return false;
55     }
56 
57     @Override
getDurationUs()58     public long getDurationUs() {
59       return durationUs;
60     }
61 
62     @Override
getSeekPoints(long timeUs)63     public SeekPoints getSeekPoints(long timeUs) {
64       return startSeekPoints;
65     }
66   }
67 
68   /** Contains one or two {@link SeekPoint}s. */
69   final class SeekPoints {
70 
71     /** The first seek point. */
72     public final SeekPoint first;
73     /** The second seek point, or {@link #first} if there's only one seek point. */
74     public final SeekPoint second;
75 
76     /** @param point The single seek point. */
SeekPoints(SeekPoint point)77     public SeekPoints(SeekPoint point) {
78       this(point, point);
79     }
80 
81     /**
82      * @param first The first seek point.
83      * @param second The second seek point.
84      */
SeekPoints(SeekPoint first, SeekPoint second)85     public SeekPoints(SeekPoint first, SeekPoint second) {
86       this.first = Assertions.checkNotNull(first);
87       this.second = Assertions.checkNotNull(second);
88     }
89 
90     @Override
toString()91     public String toString() {
92       return "[" + first + (first.equals(second) ? "" : (", " + second)) + "]";
93     }
94 
95     @Override
equals(@ullable Object obj)96     public boolean equals(@Nullable Object obj) {
97       if (this == obj) {
98         return true;
99       }
100       if (obj == null || getClass() != obj.getClass()) {
101         return false;
102       }
103       SeekPoints other = (SeekPoints) obj;
104       return first.equals(other.first) && second.equals(other.second);
105     }
106 
107     @Override
hashCode()108     public int hashCode() {
109       return (31 * first.hashCode()) + second.hashCode();
110     }
111   }
112 
113   /**
114    * Returns whether seeking is supported.
115    *
116    * @return Whether seeking is supported.
117    */
isSeekable()118   boolean isSeekable();
119 
120   /**
121    * Returns the duration of the stream in microseconds.
122    *
123    * @return The duration of the stream in microseconds, or {@link C#TIME_UNSET} if the duration is
124    *     unknown.
125    */
getDurationUs()126   long getDurationUs();
127 
128   /**
129    * Obtains seek points for the specified seek time in microseconds. The returned {@link
130    * SeekPoints} will contain one or two distinct seek points.
131    *
132    * <p>Two seek points [A, B] are returned in the case that seeking can only be performed to
133    * discrete points in time, there does not exist a seek point at exactly the requested time, and
134    * there exist seek points on both sides of it. In this case A and B are the closest seek points
135    * before and after the requested time. A single seek point is returned in all other cases.
136    *
137    * @param timeUs A seek time in microseconds.
138    * @return The corresponding seek points.
139    */
getSeekPoints(long timeUs)140   SeekPoints getSeekPoints(long timeUs);
141 }
142