shaka-player
Version:
DASH/EME video player library
356 lines (325 loc) • 9.61 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
// cspell:ignore AABBGGRR HAABBGGRR
goog.provide('shaka.text.SsaTextParser');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.text.Cue');
goog.require('shaka.text.TextEngine');
goog.require('shaka.util.StringUtils');
/**
* Documentation: http://moodub.free.fr/video/ass-specs.doc
* https://en.wikipedia.org/wiki/SubStation_Alpha
* @implements {shaka.extern.TextParser}
* @export
*/
shaka.text.SsaTextParser = class {
/**
* @override
* @export
*/
parseInit(data) {
goog.asserts.assert(false, 'SSA does not have init segments');
}
/**
* @override
* @export
*/
setSequenceMode(sequenceMode) {
// Unused.
}
/**
* @override
* @export
*/
setManifestType(manifestType) {
// Unused.
}
/**
* @override
* @export
*/
parseMedia(data, time) {
const StringUtils = shaka.util.StringUtils;
const SsaTextParser = shaka.text.SsaTextParser;
// Get the input as a string.
const str = StringUtils.fromUTF8(data);
const section = {
styles: '',
events: '',
};
let tag = null;
let lines = null;
const parts = str.split(/\r?\n\s*\r?\n/);
for (const part of parts) {
lines = part;
// SSA content
const match = SsaTextParser.ssaContent_.exec(part);
if (match) {
tag = match[1];
lines = match[2];
}
if (tag == 'V4 Styles' || tag == 'V4+ Styles') {
section.styles = lines;
if (section.events) {
section.styles += '\n' + lines;
} else {
section.styles = lines;
}
continue;
}
if (tag == 'Events') {
if (section.events) {
section.events += '\n' + lines;
} else {
section.events = lines;
}
continue;
}
if (tag == 'Script Info') {
continue;
}
shaka.log.warning('SsaTextParser parser encountered an unknown part.',
lines);
}
// Process styles
const styles = [];
// Used to be able to iterate over the style parameters.
let styleColumns = null;
const styleLines = section.styles.split(/\r?\n/);
for (const line of styleLines) {
if (/^\s*;/.test(line)) {
// Skip comment
continue;
}
const lineParts = SsaTextParser.lineParts_.exec(line);
if (lineParts) {
const name = lineParts[1].trim();
const value = lineParts[2].trim();
if (name == 'Format') {
styleColumns = value.split(SsaTextParser.valuesFormat_);
continue;
}
if (name == 'Style') {
const values = value.split(SsaTextParser.valuesFormat_);
const style = {};
for (let c = 0; c < styleColumns.length && c < values.length; c++) {
style[styleColumns[c]] = values[c];
}
styles.push(style);
continue;
}
}
}
// Process cues
/** @type {!Array<!shaka.text.Cue>} */
const cues = [];
// Used to be able to iterate over the event parameters.
let eventColumns = null;
const eventLines = section.events.split(/\r?\n/);
for (const line of eventLines) {
if (/^\s*;/.test(line)) {
// Skip comment
continue;
}
const lineParts = SsaTextParser.lineParts_.exec(line);
if (lineParts) {
const name = lineParts[1].trim();
const value = lineParts[2].trim();
if (name == 'Format') {
eventColumns = value.split(SsaTextParser.valuesFormat_);
continue;
}
if (name == 'Dialogue') {
const values = value.split(SsaTextParser.valuesFormat_);
const data = {};
for (let c = 0; c < eventColumns.length && c < values.length; c++) {
data[eventColumns[c]] = values[c];
}
const startTime = SsaTextParser.parseTime_(data['Start']);
const endTime = SsaTextParser.parseTime_(data['End']);
// Note: Normally, you should take the "Text" field, but if it
// has a comma, it fails.
const payload = values.slice(eventColumns.length - 1).join(',')
.replace(/\\N/g, '\n') // '\n' for new line
.replace(/\{[^}]+\}/g, ''); // {\pos(400,570)}
const cue = new shaka.text.Cue(startTime, endTime, payload);
const styleName = data['Style'];
const styleData = styles.find((s) => s['Name'] == styleName);
if (styleData) {
SsaTextParser.addStyle_(cue, styleData);
}
cues.push(cue);
continue;
}
}
}
return cues;
}
/**
* Adds applicable style properties to a cue.
*
* @param {shaka.text.Cue} cue
* @param {Object} style
* @private
*/
static addStyle_(cue, style) {
const Cue = shaka.text.Cue;
const SsaTextParser = shaka.text.SsaTextParser;
const fontFamily = style['Fontname'];
if (fontFamily) {
cue.fontFamily = fontFamily;
}
const fontSize = style['Fontsize'];
if (fontSize) {
cue.fontSize = fontSize + 'px';
}
const color = style['PrimaryColour'];
if (color) {
const ccsColor = SsaTextParser.parseSsaColor_(color);
if (ccsColor) {
cue.color = ccsColor;
}
}
const backgroundColor = style['BackColour'];
if (backgroundColor) {
const cssBackgroundColor = SsaTextParser.parseSsaColor_(backgroundColor);
if (cssBackgroundColor) {
cue.backgroundColor = cssBackgroundColor;
}
}
const bold = style['Bold'];
if (bold) {
cue.fontWeight = Cue.fontWeight.BOLD;
}
const italic = style['Italic'];
if (italic) {
cue.fontStyle = Cue.fontStyle.ITALIC;
}
const underline = style['Underline'];
if (underline) {
cue.textDecoration.push(Cue.textDecoration.UNDERLINE);
}
const letterSpacing = style['Spacing'];
if (letterSpacing) {
cue.letterSpacing = letterSpacing + 'px';
}
const alignment = style['Alignment'];
if (alignment) {
const alignmentInt = parseInt(alignment, 10);
switch (alignmentInt) {
case 1:
cue.displayAlign = Cue.displayAlign.AFTER;
cue.textAlign = Cue.textAlign.START;
break;
case 2:
cue.displayAlign = Cue.displayAlign.AFTER;
cue.textAlign = Cue.textAlign.CENTER;
break;
case 3:
cue.displayAlign = Cue.displayAlign.AFTER;
cue.textAlign = Cue.textAlign.END;
break;
case 5:
cue.displayAlign = Cue.displayAlign.BEFORE;
cue.textAlign = Cue.textAlign.START;
break;
case 6:
cue.displayAlign = Cue.displayAlign.BEFORE;
cue.textAlign = Cue.textAlign.CENTER;
break;
case 7:
cue.displayAlign = Cue.displayAlign.BEFORE;
cue.textAlign = Cue.textAlign.END;
break;
case 9:
cue.displayAlign = Cue.displayAlign.CENTER;
cue.textAlign = Cue.textAlign.START;
break;
case 10:
cue.displayAlign = Cue.displayAlign.CENTER;
cue.textAlign = Cue.textAlign.CENTER;
break;
case 11:
cue.displayAlign = Cue.displayAlign.CENTER;
cue.textAlign = Cue.textAlign.END;
break;
}
}
const opacity = style['AlphaLevel'];
if (opacity) {
cue.opacity = parseFloat(opacity);
}
}
/**
* Parses a SSA color .
*
* @param {string} colorString
* @return {?string}
* @private
*/
static parseSsaColor_(colorString) {
// The SSA V4+ color can be represented in hex (&HAABBGGRR) or in decimal
// format (byte order AABBGGRR) and in both cases the alpha channel's
// value needs to be inverted as in case of SSA the 0xFF alpha value means
// transparent and 0x00 means opaque
/** @type {number} */
const abgr = parseInt(colorString.replace('&H', ''), 16);
if (abgr >= 0) {
const a = ((abgr >> 24) & 0xFF) ^ 0xFF; // Flip alpha.
const alpha = a / 255;
const b = (abgr >> 16) & 0xFF;
const g = (abgr >> 8) & 0xFF;
const r = abgr & 0xff;
return 'rgba(' + r + ',' + g + ',' + b + ',' + alpha + ')';
}
return null;
}
/**
* Parses a SSA time from the given parser.
*
* @param {string} string
* @return {number}
* @private
*/
static parseTime_(string) {
const SsaTextParser = shaka.text.SsaTextParser;
const match = SsaTextParser.timeFormat_.exec(string);
const hours = match[1] ? parseInt(match[1].replace(':', ''), 10) : 0;
const minutes = parseInt(match[2], 10);
const seconds = parseFloat(match[3]);
return hours * 3600 + minutes * 60 + seconds;
}
};
/**
* @const
* @private {!RegExp}
* @example [V4 Styles]\nFormat: Name\nStyle: DefaultVCD
*/
shaka.text.SsaTextParser.ssaContent_ =
/^\s*\[([^\]]+)\]\r?\n([\s\S]*)/;
/**
* @const
* @private {!RegExp}
* @example Style: DefaultVCD,...
*/
shaka.text.SsaTextParser.lineParts_ =
/^\s*([^:]+):\s*(.*)/;
/**
* @const
* @private {!RegExp}
* @example Style: DefaultVCD,...
*/
shaka.text.SsaTextParser.valuesFormat_ = /\s*,\s*/;
/**
* @const
* @private {!RegExp}
* @example 0:00:01.1 or 0:00:01.18 or 0:00:01.180
*/
shaka.text.SsaTextParser.timeFormat_ =
/^(\d+:)?(\d{1,2}):(\d{1,2}(?:[.]\d{1,3})?)?$/;
shaka.text.TextEngine.registerParser(
'text/x-ssa', () => new shaka.text.SsaTextParser());