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* Timeline Controller
*/
import Event from '../events';
import EventHandler from '../event-handler';
import Cea608Parser from '../utils/cea-608-parser';
import OutputFilter from '../utils/output-filter';
import WebVTTParser from '../utils/webvtt-parser';
import { logger } from '../utils/logger';
import { sendAddTrackEvent, clearCurrentCues } from '../utils/texttrack-utils';
function reuseVttTextTrack (inUseTrack, manifestTrack) {
return inUseTrack && inUseTrack.label === manifestTrack.name && !(inUseTrack.textTrack1 || inUseTrack.textTrack2);
}
function intersection (x1, x2, y1, y2) {
return Math.min(x2, y2) - Math.max(x1, y1);
}
class TimelineController extends EventHandler {
constructor (hls) {
super(hls, Event.MEDIA_ATTACHING,
Event.MEDIA_DETACHING,
Event.FRAG_PARSING_USERDATA,
Event.FRAG_DECRYPTED,
Event.MANIFEST_LOADING,
Event.MANIFEST_LOADED,
Event.FRAG_LOADED,
Event.LEVEL_SWITCHING,
Event.INIT_PTS_FOUND);
this.hls = hls;
this.config = hls.config;
this.enabled = true;
this.Cues = hls.config.cueHandler;
this.textTracks = [];
this.tracks = [];
this.unparsedVttFrags = [];
this.initPTS = undefined;
this.cueRanges = [];
Eif (this.config.enableCEA708Captions) {
let channel1 = new OutputFilter(this, 1);
let channel2 = new OutputFilter(this, 2);
this.cea608Parser = new Cea608Parser(0, channel1, channel2);
}
}
addCues (channel, startTime, endTime, screen) {
// skip cues which overlap more than 50% with previously parsed time ranges
const ranges = this.cueRanges;
let merged = false;
for (let i = ranges.length; i--;) {
let cueRange = ranges[i];
let overlap = intersection(cueRange[0], cueRange[1], startTime, endTime);
if (overlap >= 0) {
cueRange[0] = Math.min(cueRange[0], startTime);
cueRange[1] = Math.max(cueRange[1], endTime);
merged = true;
if ((overlap / (endTime - startTime)) > 0.5)
return;
}
}
if (!merged)
ranges.push([startTime, endTime]);
this.Cues.newCue(this[channel], startTime, endTime, screen);
}
// Triggered when an initial PTS is found; used for synchronisation of WebVTT.
onInitPtsFound (data) {
if (typeof this.initPTS === 'undefined')
this.initPTS = data.initPTS;
// Due to asynchrony, initial PTS may arrive later than the first VTT fragments are loaded.
// Parse any unparsed fragments upon receiving the initial PTS.
if (this.unparsedVttFrags.length) {
this.unparsedVttFrags.forEach(frag => {
this.onFragLoaded(frag);
});
this.unparsedVttFrags = [];
}
}
getExistingTrack (channelNumber) {
const media = this.media;
if (media) {
for (let i = 0; i < media.textTracks.length; i++) {
let textTrack = media.textTracks[i];
let propName = 'textTrack' + channelNumber;
if (textTrack[propName] === true)
return textTrack;
}
}
return null;
}
createCaptionsTrack (track) {
let trackVar = 'textTrack' + track;
if (!this[trackVar]) {
// Enable reuse of existing text track.
let existingTrack = this.getExistingTrack(track);
if (!existingTrack) {
const textTrack = this.createTextTrack('captions', this.config['captionsTextTrack' + track + 'Label'], this.config['captionsTextTrack' + track + 'LanguageCode']);
if (textTrack) {
textTrack[trackVar] = true;
this[trackVar] = textTrack;
}
} else {
this[trackVar] = existingTrack;
clearCurrentCues(this[trackVar]);
sendAddTrackEvent(this[trackVar], this.media);
}
}
}
createTextTrack (kind, label, lang) {
const media = this.media;
Eif (media)
return media.addTextTrack(kind, label, lang);
}
destroy () {
EventHandler.prototype.destroy.call(this);
}
onMediaAttaching (data) {
this.media = data.media;
this._cleanTracks();
}
onMediaDetaching () {
clearCurrentCues(this.textTrack1);
clearCurrentCues(this.textTrack2);
}
onManifestLoading () {
this.lastSn = -1; // Detect discontiguity in fragment parsing
this.prevCC = -1;
this.vttCCs = { ccOffset: 0, presentationOffset: 0 }; // Detect discontinuity in subtitle manifests
this._cleanTracks();
}
_cleanTracks () {
// clear outdated subtitles
const media = this.media;
if (media) {
const textTracks = media.textTracks;
if (textTracks) {
for (let i = 0; i < textTracks.length; i++)
clearCurrentCues(textTracks[i]);
}
}
}
onManifestLoaded (data) {
this.textTracks = [];
this.unparsedVttFrags = this.unparsedVttFrags || [];
this.initPTS = undefined;
this.cueRanges = [];
Eif (this.config.enableWebVTT) {
this.tracks = data.subtitles || [];
const inUseTracks = this.media ? this.media.textTracks : [];
this.tracks.forEach((track, index) => {
let textTrack;
Iif (index < inUseTracks.length) {
const inUseTrack = inUseTracks[index];
// Reuse tracks with the same label, but do not reuse 608/708 tracks
if (reuseVttTextTrack(inUseTrack, track))
textTrack = inUseTrack;
}
Eif (!textTrack)
textTrack = this.createTextTrack('subtitles', track.name, track.lang);
if (track.default)
textTrack.mode = this.hls.subtitleDisplay ? 'showing' : 'hidden';
else
textTrack.mode = 'disabled';
this.textTracks.push(textTrack);
});
}
}
onLevelSwitching () {
this.enabled = this.hls.currentLevel.closedCaptions !== 'NONE';
}
onFragLoaded (data) {
let frag = data.frag,
payload = data.payload;
if (frag.type === 'main') {
let sn = frag.sn;
// if this frag isn't contiguous, clear the parser so cues with bad start/end times aren't added to the textTrack
if (sn !== this.lastSn + 1) {
const cea608Parser = this.cea608Parser;
Eif (cea608Parser)
cea608Parser.reset();
}
this.lastSn = sn;
} // eslint-disable-line brace-style
// If fragment is subtitle type, parse as WebVTT.
else Iif (frag.type === 'subtitle') {
if (payload.byteLength) {
// We need an initial synchronisation PTS. Store fragments as long as none has arrived.
if (typeof this.initPTS === 'undefined') {
this.unparsedVttFrags.push(data);
return;
}
let decryptData = frag.decryptdata;
// If the subtitles are not encrypted, parse VTTs now. Otherwise, we need to wait.
if ((decryptData == null) || (decryptData.key == null) || (decryptData.method !== 'AES-128'))
this._parseVTTs(frag, payload);
} else {
// In case there is no payload, finish unsuccessfully.
this.hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag: frag });
}
}
}
_parseVTTs (frag, payload) {
let vttCCs = this.vttCCs;
if (!vttCCs[frag.cc]) {
vttCCs[frag.cc] = { start: frag.start, prevCC: this.prevCC, new: true };
this.prevCC = frag.cc;
}
let textTracks = this.textTracks,
hls = this.hls;
// Parse the WebVTT file contents.
WebVTTParser.parse(payload, this.initPTS, vttCCs, frag.cc, function (cues) {
const currentTrack = textTracks[frag.trackId];
// WebVTTParser.parse is an async method and if the currently selected text track mode is set to "disabled"
// before parsing is done then don't try to access currentTrack.cues.getCueById as cues will be null
// and trying to access getCueById method of cues will throw an exception
if (currentTrack.mode === 'disabled') {
hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag: frag });
return;
}
// Add cues and trigger event with success true.
cues.forEach(cue => {
// Sometimes there are cue overlaps on segmented vtts so the same
// cue can appear more than once in different vtt files.
// This avoid showing duplicated cues with same timecode and text.
if (!currentTrack.cues.getCueById(cue.id)) {
try {
currentTrack.addCue(cue);
} catch (err) {
const textTrackCue = new window.TextTrackCue(cue.startTime, cue.endTime, cue.text);
textTrackCue.id = cue.id;
currentTrack.addCue(textTrackCue);
}
}
}
);
hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: true, frag: frag });
},
function (e) {
// Something went wrong while parsing. Trigger event with success false.
logger.log(`Failed to parse VTT cue: ${e}`);
hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag: frag });
});
}
onFragDecrypted (data) {
let decryptedData = data.payload,
frag = data.frag;
if (frag.type === 'subtitle') {
if (typeof this.initPTS === 'undefined') {
this.unparsedVttFrags.push(data);
return;
}
this._parseVTTs(frag, decryptedData);
}
}
onFragParsingUserdata (data) {
// push all of the CEA-708 messages into the interpreter
// immediately. It will create the proper timestamps based on our PTS value
if (this.enabled && this.config.enableCEA708Captions) {
for (let i = 0; i < data.samples.length; i++) {
let ccdatas = this.extractCea608Data(data.samples[i].bytes);
this.cea608Parser.addData(data.samples[i].pts, ccdatas);
}
}
}
extractCea608Data (byteArray) {
let count = byteArray[0] & 31;
let position = 2;
let tmpByte, ccbyte1, ccbyte2, ccValid, ccType;
let actualCCBytes = [];
for (let j = 0; j < count; j++) {
tmpByte = byteArray[position++];
ccbyte1 = 0x7F & byteArray[position++];
ccbyte2 = 0x7F & byteArray[position++];
ccValid = (4 & tmpByte) !== 0;
ccType = 3 & tmpByte;
if (ccbyte1 === 0 && ccbyte2 === 0)
continue;
if (ccValid) {
if (ccType === 0) { // || ccType === 1
actualCCBytes.push(ccbyte1);
actualCCBytes.push(ccbyte2);
}
}
}
return actualCCBytes;
}
}
export default TimelineController;
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