1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/*
* 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 org.mozilla.thirdparty.com.google.android.exoplayer2.text.webvtt;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.ParserException;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Utility methods for parsing WebVTT data.
*/
public final class WebvttParserUtil {
private static final Pattern COMMENT = Pattern.compile("^NOTE([ \t].*)?$");
private static final String WEBVTT_HEADER = "WEBVTT";
private WebvttParserUtil() {}
/**
* Reads and validates the first line of a WebVTT file.
*
* @param input The input from which the line should be read.
* @throws ParserException If the line isn't the start of a valid WebVTT file.
*/
public static void validateWebvttHeaderLine(ParsableByteArray input) throws ParserException {
int startPosition = input.getPosition();
if (!isWebvttHeaderLine(input)) {
input.setPosition(startPosition);
throw new ParserException("Expected WEBVTT. Got " + input.readLine());
}
}
/**
* Returns whether the given input is the first line of a WebVTT file.
*
* @param input The input from which the line should be read.
*/
public static boolean isWebvttHeaderLine(ParsableByteArray input) {
@Nullable String line = input.readLine();
return line != null && line.startsWith(WEBVTT_HEADER);
}
/**
* Parses a WebVTT timestamp.
*
* @param timestamp The timestamp string.
* @return The parsed timestamp in microseconds.
* @throws NumberFormatException If the timestamp could not be parsed.
*/
public static long parseTimestampUs(String timestamp) throws NumberFormatException {
long value = 0;
String[] parts = Util.splitAtFirst(timestamp, "\\.");
String[] subparts = Util.split(parts[0], ":");
for (String subpart : subparts) {
value = (value * 60) + Long.parseLong(subpart);
}
value *= 1000;
if (parts.length == 2) {
value += Long.parseLong(parts[1]);
}
return value * 1000;
}
/**
* Parses a percentage string.
*
* @param s The percentage string.
* @return The parsed value, where 1.0 represents 100%.
* @throws NumberFormatException If the percentage could not be parsed.
*/
public static float parsePercentage(String s) throws NumberFormatException {
if (!s.endsWith("%")) {
throw new NumberFormatException("Percentages must end with %");
}
return Float.parseFloat(s.substring(0, s.length() - 1)) / 100;
}
/**
* Reads lines up to and including the next WebVTT cue header.
*
* @param input The input from which lines should be read.
* @return A {@link Matcher} for the WebVTT cue header, or null if the end of the input was
* reached without a cue header being found. In the case that a cue header is found, groups 1,
* 2 and 3 of the returned matcher contain the start time, end time and settings list.
*/
@Nullable
public static Matcher findNextCueHeader(ParsableByteArray input) {
@Nullable String line;
while ((line = input.readLine()) != null) {
if (COMMENT.matcher(line).matches()) {
// Skip until the end of the comment block.
while ((line = input.readLine()) != null && !line.isEmpty()) {}
} else {
Matcher cueHeaderMatcher = WebvttCueParser.CUE_HEADER_PATTERN.matcher(line);
if (cueHeaderMatcher.matches()) {
return cueHeaderMatcher;
}
}
}
return null;
}
}
|