Expose cue settings parser
This CL exposes the cue settings parser in order to allow its usage from the MP4Webvtt extractor. Also fixes a few mistakes from the previous related CL. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=112145806
This commit is contained in:
aquilescanta
Oliver Woodman
parent
6b9a1b16f1
commit
b6b97a8683
@ -18,6 +18,7 @@ package com.google.android.exoplayer.text.webvtt;
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import com.google.android.exoplayer.text.Cue;
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import android.text.Layout.Alignment;
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import android.util.Log;
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/**
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* A representation of a WebVTT cue.
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@ -53,4 +54,127 @@ import android.text.Layout.Alignment;
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return (line == DIMEN_UNSET && position == DIMEN_UNSET);
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}
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/**
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* Builder for WebVTT cues.
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*/
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@SuppressWarnings("hiding")
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public static final class Builder {
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private static final String TAG = "WebvttCueBuilder";
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private long startTime;
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private long endTime;
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private CharSequence text;
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private Alignment textAlignment;
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private float line;
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private int lineType;
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private int lineAnchor;
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private float position;
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private int positionAnchor;
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private float width;
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// Initialization methods
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public Builder() {
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reset();
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}
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public void reset() {
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startTime = 0;
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endTime = 0;
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text = null;
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textAlignment = null;
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line = Cue.DIMEN_UNSET;
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lineType = Cue.TYPE_UNSET;
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lineAnchor = Cue.TYPE_UNSET;
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position = Cue.DIMEN_UNSET;
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positionAnchor = Cue.TYPE_UNSET;
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width = Cue.DIMEN_UNSET;
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}
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// Construction methods
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public WebvttCue build() {
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if (position != Cue.DIMEN_UNSET && positionAnchor == Cue.TYPE_UNSET) {
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derivePositionAnchorFromAlignment();
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}
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return new WebvttCue(startTime, endTime, text, textAlignment, line, lineType, lineAnchor,
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position, positionAnchor, width);
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}
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public Builder setStartTime(long time) {
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startTime = time;
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return this;
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}
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public Builder setEndTime(long time) {
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endTime = time;
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return this;
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}
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public Builder setText(CharSequence aText) {
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text = aText;
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return this;
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}
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public Builder setTextAlignment(Alignment textAlignment) {
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this.textAlignment = textAlignment;
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return this;
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}
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public Builder setLine(float line) {
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this.line = line;
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return this;
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}
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public Builder setLineType(int lineType) {
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this.lineType = lineType;
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return this;
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}
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public Builder setLineAnchor(int lineAnchor) {
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this.lineAnchor = lineAnchor;
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return this;
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}
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public Builder setPosition(float position) {
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this.position = position;
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return this;
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}
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public Builder setPositionAnchor(int positionAnchor) {
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this.positionAnchor = positionAnchor;
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return this;
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}
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public Builder setWidth(float width) {
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this.width = width;
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return this;
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}
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private Builder derivePositionAnchorFromAlignment() {
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if (textAlignment == null) {
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positionAnchor = Cue.TYPE_UNSET;
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} else {
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switch (textAlignment) {
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case ALIGN_NORMAL:
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positionAnchor = Cue.ANCHOR_TYPE_START;
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break;
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case ALIGN_CENTER:
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positionAnchor = Cue.ANCHOR_TYPE_MIDDLE;
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break;
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case ALIGN_OPPOSITE:
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positionAnchor = Cue.ANCHOR_TYPE_END;
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break;
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default:
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Log.w(TAG, "Unrecognized alignment: " + textAlignment);
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positionAnchor = Cue.ANCHOR_TYPE_START;
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break;
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}
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}
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return this;
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}
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}
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}
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@ -31,7 +31,7 @@ import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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/**
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* Parser for webvtt cue text. (https://w3c.github.io/webvtt/#cue-text)
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* Parser for WebVTT cues. (https://w3c.github.io/webvtt/#cues)
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*/
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public final class WebvttCueParser {
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@ -66,71 +66,50 @@ public final class WebvttCueParser {
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private static final String TAG = "WebvttCueParser";
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private StringBuilder textBuilder;
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private PositionHolder positionHolder;
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private final StringBuilder textBuilder;
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public WebvttCueParser() {
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positionHolder = new PositionHolder();
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textBuilder = new StringBuilder();
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}
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/**
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* Parses the next valid Webvtt cue in a parsable array, including timestamps, settings and text.
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* Parses the next valid WebVTT cue in a parsable array, including timestamps, settings and text.
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*
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* @param webvttData parsable Webvtt file data.
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* @return a {@link WebvttCue} instance if cue content is found. {@code null} otherwise.
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* @param webvttData Parsable WebVTT file data.
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* @param cueBuilder Builder for WebVTT Cues.
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* @return True if a valid Cue was found, false otherwise.
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*/
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public WebvttCue parseNextValidCue(ParsableByteArray webvttData) {
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public boolean parseNextValidCue(ParsableByteArray webvttData, WebvttCue.Builder cueBuilder) {
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Matcher cueHeaderMatcher;
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while ((cueHeaderMatcher = findNextCueHeader(webvttData)) != null) {
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WebvttCue currentCue = parseCue(cueHeaderMatcher, webvttData);
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if (currentCue != null) {
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return currentCue;
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if (parseCue(cueHeaderMatcher, webvttData, cueBuilder, textBuilder)) {
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return true;
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}
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}
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return null;
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return false;
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}
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private WebvttCue parseCue(Matcher cueHeaderMatcher, ParsableByteArray webvttData) {
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long cueStartTime;
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long cueEndTime;
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try {
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// Parse the cue start and end times.
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cueStartTime = WebvttParserUtil.parseTimestampUs(cueHeaderMatcher.group(1));
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cueEndTime = WebvttParserUtil.parseTimestampUs(cueHeaderMatcher.group(2));
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} catch (NumberFormatException e) {
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Log.w(TAG, "Skipping cue with bad header: " + cueHeaderMatcher.group());
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return null;
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}
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// Default cue settings.
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Alignment cueTextAlignment = null;
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float cueLine = Cue.DIMEN_UNSET;
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int cueLineType = Cue.TYPE_UNSET;
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int cueLineAnchor = Cue.TYPE_UNSET;
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float cuePosition = Cue.DIMEN_UNSET;
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int cuePositionAnchor = Cue.TYPE_UNSET;
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float cueWidth = Cue.DIMEN_UNSET;
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/**
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* Parses a string containing a list of cue settings.
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*
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* @param cueSettingsList String containing the settings for a given cue.
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* @param builder The {@link WebvttCue.Builder} where incremental construction takes place.
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*/
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public static void parseCueSettingsList(String cueSettingsList, WebvttCue.Builder builder) {
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// Parse the cue settings list.
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Matcher cueSettingMatcher = CUE_SETTING_PATTERN.matcher(cueHeaderMatcher.group(3));
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Matcher cueSettingMatcher = CUE_SETTING_PATTERN.matcher(cueSettingsList);
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while (cueSettingMatcher.find()) {
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String name = cueSettingMatcher.group(1);
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String value = cueSettingMatcher.group(2);
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try {
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if ("line".equals(name)) {
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parseLineAttribute(value, positionHolder);
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cueLine = positionHolder.position;
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cueLineType = positionHolder.lineType;
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cueLineAnchor = positionHolder.positionAnchor;
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parseLineAttribute(value, builder);
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} else if ("align".equals(name)) {
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cueTextAlignment = parseTextAlignment(value);
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builder.setTextAlignment(parseTextAlignment(value));
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} else if ("position".equals(name)) {
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parsePositionAttribute(value, positionHolder);
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cuePosition = positionHolder.position;
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cuePositionAnchor = positionHolder.positionAnchor;
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parsePositionAttribute(value, builder);
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} else if ("size".equals(name)) {
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cueWidth = WebvttParserUtil.parsePercentage(value);
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builder.setWidth(WebvttParserUtil.parsePercentage(value));
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} else {
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Log.w(TAG, "Unknown cue setting " + name + ":" + value);
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}
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@ -138,12 +117,44 @@ public final class WebvttCueParser {
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Log.w(TAG, "Skipping bad cue setting: " + cueSettingMatcher.group());
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}
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}
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}
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if (cuePosition != Cue.DIMEN_UNSET && cuePositionAnchor == Cue.TYPE_UNSET) {
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// Computed position alignment should be derived from the text alignment if it has not been
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// set explicitly.
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cuePositionAnchor = alignmentToAnchor(cueTextAlignment);
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/**
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* Reads lines up to and including the next WebVTT cue header.
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*
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* @param input The input from which lines should be read.
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* @return A {@link Matcher} for the WebVTT cue header, or null if the end of the input was
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* reached without a cue header being found. In the case that a cue header is found, groups 1,
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* 2 and 3 of the returned matcher contain the start time, end time and settings list.
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*/
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public static Matcher findNextCueHeader(ParsableByteArray input) {
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String line;
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while ((line = input.readLine()) != null) {
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if (COMMENT.matcher(line).matches()) {
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// Skip until the end of the comment block.
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while ((line = input.readLine()) != null && !line.isEmpty()) {}
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} else {
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Matcher cueHeaderMatcher = WebvttCueParser.CUE_HEADER_PATTERN.matcher(line);
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if (cueHeaderMatcher.matches()) {
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return cueHeaderMatcher;
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}
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}
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}
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return null;
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}
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private static boolean parseCue(Matcher cueHeaderMatcher, ParsableByteArray webvttData,
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WebvttCue.Builder builder, StringBuilder textBuilder) {
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try {
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// Parse the cue start and end times.
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builder.setStartTime(WebvttParserUtil.parseTimestampUs(cueHeaderMatcher.group(1)))
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.setEndTime(WebvttParserUtil.parseTimestampUs(cueHeaderMatcher.group(2)));
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} catch (NumberFormatException e) {
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Log.w(TAG, "Skipping cue with bad header: " + cueHeaderMatcher.group());
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return false;
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}
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parseCueSettingsList(cueHeaderMatcher.group(3), builder);
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// Parse the cue text.
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textBuilder.setLength(0);
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@ -154,11 +165,8 @@ public final class WebvttCueParser {
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}
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textBuilder.append(line.trim());
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}
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CharSequence cueText = parseCueText(textBuilder.toString());
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return new WebvttCue(cueStartTime, cueEndTime, cueText, cueTextAlignment, cueLine,
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cueLineType, cueLineAnchor, cuePosition, cuePositionAnchor, cueWidth);
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builder.setText(parseCueText(textBuilder.toString()));
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return true;
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}
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/* package */ static Spanned parseCueText(String markup) {
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@ -226,77 +234,34 @@ public final class WebvttCueParser {
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return spannedText;
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}
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/**
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* Reads lines up to and including the next WebVTT cue header.
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*
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* @param input The input from which lines should be read.
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* @return A {@link Matcher} for the WebVTT cue header, or null if the end of the input was
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* reached without a cue header being found. In the case that a cue header is found, groups 1,
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* 2 and 3 of the returned matcher contain the start time, end time and settings list.
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*/
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public static Matcher findNextCueHeader(ParsableByteArray input) {
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String line;
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while ((line = input.readLine()) != null) {
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if (COMMENT.matcher(line).matches()) {
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// Skip until the end of the comment block.
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while ((line = input.readLine()) != null && !line.isEmpty()) {}
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} else {
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Matcher cueHeaderMatcher = WebvttCueParser.CUE_HEADER_PATTERN.matcher(line);
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if (cueHeaderMatcher.matches()) {
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return cueHeaderMatcher;
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}
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}
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}
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return null;
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}
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private static final class PositionHolder {
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public float position;
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public int positionAnchor;
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public int lineType;
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}
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// Internal methods
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private static void parseLineAttribute(String s, PositionHolder out)
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private static void parseLineAttribute(String s, WebvttCue.Builder builder)
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throws NumberFormatException {
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int lineAnchor;
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int commaPosition = s.indexOf(',');
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if (commaPosition != -1) {
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lineAnchor = parsePositionAnchor(s.substring(commaPosition + 1));
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builder.setLineAnchor(parsePositionAnchor(s.substring(commaPosition + 1)));
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s = s.substring(0, commaPosition);
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} else {
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lineAnchor = Cue.TYPE_UNSET;
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builder.setLineAnchor(Cue.TYPE_UNSET);
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}
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float line;
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int lineType;
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if (s.endsWith("%")) {
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line = WebvttParserUtil.parsePercentage(s);
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lineType = Cue.LINE_TYPE_FRACTION;
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builder.setLine(WebvttParserUtil.parsePercentage(s)).setLineType(Cue.LINE_TYPE_FRACTION);
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} else {
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line = Integer.parseInt(s);
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lineType = Cue.LINE_TYPE_NUMBER;
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builder.setLine(Integer.parseInt(s)).setLineType(Cue.LINE_TYPE_NUMBER);
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}
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out.position = line;
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out.positionAnchor = lineAnchor;
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out.lineType = lineType;
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}
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private static void parsePositionAttribute(String s, PositionHolder out)
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private static void parsePositionAttribute(String s, WebvttCue.Builder builder)
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throws NumberFormatException {
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int positionAnchor;
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int commaPosition = s.indexOf(',');
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if (commaPosition != -1) {
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positionAnchor = parsePositionAnchor(s.substring(commaPosition + 1));
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builder.setPositionAnchor(parsePositionAnchor(s.substring(commaPosition + 1)));
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s = s.substring(0, commaPosition);
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} else {
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positionAnchor = Cue.TYPE_UNSET;
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builder.setPositionAnchor(Cue.TYPE_UNSET);
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}
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out.position = WebvttParserUtil.parsePercentage(s);
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out.positionAnchor = positionAnchor;
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out.lineType = Cue.TYPE_UNSET;
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builder.setPosition(WebvttParserUtil.parsePercentage(s));
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}
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private static int parsePositionAnchor(String s) {
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@ -329,27 +294,10 @@ public final class WebvttCueParser {
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}
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}
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private static int alignmentToAnchor(Alignment alignment) {
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if (alignment == null) {
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return Cue.TYPE_UNSET;
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}
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switch (alignment) {
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case ALIGN_NORMAL:
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return Cue.ANCHOR_TYPE_START;
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case ALIGN_CENTER:
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return Cue.ANCHOR_TYPE_MIDDLE;
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case ALIGN_OPPOSITE:
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return Cue.ANCHOR_TYPE_END;
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default:
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Log.w(TAG, "Unrecognized alignment: " + alignment);
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return Cue.ANCHOR_TYPE_START;
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}
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}
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/**
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* Find end of tag (>). The position returned is the position of the > plus one (exclusive).
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*
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* @param markup The webvtt cue markup to be parsed.
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* @param markup The WebVTT cue markup to be parsed.
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* @param startPos the position from where to start searching for the end of tag.
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* @return the position of the end of tag plus 1 (one).
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*/
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@ -33,10 +33,12 @@ public final class WebvttParser implements SubtitleParser {
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private final WebvttCueParser cueParser;
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private final ParsableByteArray parsableWebvttData;
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private final WebvttCue.Builder webvttCueBuilder;
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public WebvttParser() {
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cueParser = new WebvttCueParser();
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parsableWebvttData = new ParsableByteArray();
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webvttCueBuilder = new WebvttCue.Builder();
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}
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@Override
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@ -48,6 +50,7 @@ public final class WebvttParser implements SubtitleParser {
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public final WebvttSubtitle parse(byte[] bytes, int offset, int length) throws ParserException {
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parsableWebvttData.reset(bytes, offset + length);
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parsableWebvttData.setPosition(offset);
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webvttCueBuilder.reset(); // In case a previous parse run failed with a ParserException.
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// Validate the first line of the header, and skip the remainder.
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WebvttParserUtil.validateWebvttHeaderLine(parsableWebvttData);
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@ -55,9 +58,9 @@ public final class WebvttParser implements SubtitleParser {
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// Extract Cues
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ArrayList<WebvttCue> subtitles = new ArrayList<>();
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WebvttCue currentWebvttCue;
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while ((currentWebvttCue = cueParser.parseNextValidCue(parsableWebvttData)) != null) {
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subtitles.add(currentWebvttCue);
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while (cueParser.parseNextValidCue(parsableWebvttData, webvttCueBuilder)) {
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subtitles.add(webvttCueBuilder.build());
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webvttCueBuilder.reset();
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}
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return new WebvttSubtitle(subtitles);
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}
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