forked from video-dev/hls.js
/
timeline-controller.ts
385 lines (346 loc) · 12.5 KB
/
timeline-controller.ts
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import Event from '../events';
import EventHandler from '../event-handler';
import Cea608Parser, { CaptionScreen } 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';
import Fragment from '../loader/fragment';
import { HlsConfig } from '../config';
// TS todo: Reduce usage of any
class TimelineController extends EventHandler {
private media: HTMLMediaElement | null = null;
private config: HlsConfig;
private enabled: boolean = true;
private Cues: any;
private textTracks: Array<TextTrack> = [];
private tracks: Array<any> = [];
private initPTS: Array<number> = [];
private unparsedVttFrags: Array<{frag: Fragment, payload: any}> = [];
private cueRanges: Array<any> = [];
private captionsTracks: any = {};
private captionsProperties: any;
private cea608Parser: Cea608Parser;
private lastSn: number = -1;
private prevCC: number = -1;
private vttCCs: any = null;
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.Cues = hls.config.cueHandler;
this.captionsProperties = {
textTrack1: {
label: this.config.captionsTextTrack1Label,
languageCode: this.config.captionsTextTrack1LanguageCode
},
textTrack2: {
label: this.config.captionsTextTrack2Label,
languageCode: this.config.captionsTextTrack2LanguageCode
}
};
if (this.config.enableCEA708Captions) {
const channel1 = new OutputFilter(this, 'textTrack1');
const channel2 = new OutputFilter(this, 'textTrack2');
this.cea608Parser = new Cea608Parser(0, channel1, channel2);
}
}
addCues (trackName: string, startTime: number, endTime: number, screen: CaptionScreen) {
// 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.captionsTracks[trackName], startTime, endTime, screen);
}
// Triggered when an initial PTS is found; used for synchronisation of WebVTT.
onInitPtsFound (data: { id: string, frag: Fragment, initPTS: number}) {
const { frag, id, initPTS } = data;
const { unparsedVttFrags } = this;
if (id === 'main') {
this.initPTS[frag.cc] = initPTS;
}
// Due to asynchronous processing, initial PTS may arrive later than the first VTT fragments are loaded.
// Parse any unparsed fragments upon receiving the initial PTS.
if (unparsedVttFrags.length) {
this.unparsedVttFrags = [];
unparsedVttFrags.forEach(frag => {
this.onFragLoaded(frag);
});
}
}
getExistingTrack (trackName: string): TextTrack | null {
const { media } = this;
if (media) {
for (let i = 0; i < media.textTracks.length; i++) {
let textTrack = media.textTracks[i];
if (textTrack[trackName]) {
return textTrack;
}
}
}
return null;
}
createCaptionsTrack (trackName: string) {
const { captionsProperties, captionsTracks, media } = this;
const { label, languageCode } = captionsProperties[trackName];
if (!captionsTracks[trackName]) {
// Enable reuse of existing text track.
const existingTrack = this.getExistingTrack(trackName);
if (!existingTrack) {
const textTrack = this.createTextTrack('captions', label, languageCode);
if (textTrack) {
// Set a special property on the track so we know it's managed by Hls.js
textTrack[trackName] = true;
captionsTracks[trackName] = textTrack;
}
} else {
captionsTracks[trackName] = existingTrack;
clearCurrentCues(captionsTracks[trackName]);
sendAddTrackEvent(captionsTracks[trackName], media);
}
}
}
createTextTrack (kind: TextTrackKind, label: string, lang: string): TextTrack | undefined {
const media = this.media;
if (!media) {
return;
}
return media.addTextTrack(kind, label, lang);
}
destroy () {
super.destroy();
}
onMediaAttaching (data: { media: HTMLMediaElement }) {
this.media = data.media;
this._cleanTracks();
}
onMediaDetaching () {
const { captionsTracks } = this;
Object.keys(captionsTracks).forEach(trackName => {
clearCurrentCues(captionsTracks[trackName]);
delete captionsTracks[trackName];
});
}
onManifestLoading () {
this.lastSn = -1; // Detect discontiguity in fragment parsing
this.prevCC = -1;
this.vttCCs = { // Detect discontinuity in subtitle manifests
ccOffset: 0,
presentationOffset: 0,
0: {
start: 0, prevCC: -1, new: false
}
};
this._cleanTracks();
}
_cleanTracks () {
// clear outdated subtitles
const { media } = this;
if (!media) {
return;
}
const textTracks = media.textTracks;
if (textTracks) {
for (let i = 0; i < textTracks.length; i++) {
clearCurrentCues(textTracks[i]);
}
}
}
onManifestLoaded (data: { subtitles: Array<any> }) {
this.textTracks = [];
this.unparsedVttFrags = this.unparsedVttFrags || [];
this.initPTS = [];
this.cueRanges = [];
if (this.config.enableWebVTT) {
this.tracks = data.subtitles || [];
const inUseTracks = this.media ? this.media.textTracks : [];
this.tracks.forEach((track, index) => {
let textTrack;
if (index < inUseTracks.length) {
let inUseTrack = null;
for (let i = 0; i < inUseTracks.length; i++) {
if (canReuseVttTextTrack(inUseTracks[i], track)) {
inUseTrack = inUseTracks[i];
break;
}
}
// Reuse tracks with the same label, but do not reuse 608/708 tracks
if (inUseTrack) {
textTrack = inUseTrack;
}
}
if (!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: { frag: Fragment, payload: any }) {
const { frag, payload } = data;
const { cea608Parser, initPTS, lastSn, unparsedVttFrags } = this;
if (frag.type === 'main') {
const 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 (frag.sn !== lastSn + 1) {
if (cea608Parser) {
cea608Parser.reset();
}
}
this.lastSn = sn as number;
} // eslint-disable-line brace-style
// If fragment is subtitle type, parse as WebVTT.
else if (frag.type === 'subtitle') {
if (payload.byteLength) {
// We need an initial synchronisation PTS. Store fragments as long as none has arrived.
if (!Number.isFinite(initPTS[frag.cc])) {
unparsedVttFrags.push(data);
if (initPTS.length) {
// finish unsuccessfully, otherwise the subtitle-stream-controller could be blocked from loading new frags.
this.hls.trigger(Event.SUBTITLE_FRAG_PROCESSED, { success: false, frag });
}
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 });
}
}
}
_parseVTTs (frag: Fragment, payload) {
const { hls, prevCC, textTracks, vttCCs } = this;
if (!vttCCs[frag.cc]) {
vttCCs[frag.cc] = { start: frag.start, prevCC, new: true };
this.prevCC = frag.cc;
}
// Parse the WebVTT file contents.
WebVTTParser.parse(payload, this.initPTS[frag.cc], vttCCs, frag.cc, function (cues) {
const currentTrack = textTracks[frag.level];
// 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 => {
const addTextTrackCue = (track, cue) => {
const textTrackCue = new (window as any).TextTrackCue(cue.startTime, cue.endTime, cue.text);
textTrackCue.id = cue.id;
track.addCue(textTrackCue);
};
// 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)) {
if (hls.config.forceTextTrackCue) {
addTextTrackCue(currentTrack, cue);
} else {
try {
currentTrack.addCue(cue);
} catch (err) {
addTextTrackCue(currentTrack, cue);
}
}
}
}
);
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: { frag: Fragment, payload: any}) {
const { frag, payload } = data;
if (frag.type === 'subtitle') {
if (!Number.isFinite(this.initPTS[frag.cc])) {
this.unparsedVttFrags.push(data);
return;
}
this._parseVTTs(frag, payload);
}
}
onFragParsingUserdata (data: { samples: Array<any> }) {
if (!this.enabled || !this.config.enableCEA708Captions) {
return;
}
// If the event contains captions (found in the bytes property), push all bytes into the parser immediately
// It will create the proper timestamps based on the PTS value
for (let i = 0; i < data.samples.length; i++) {
const ccBytes = data.samples[i].bytes;
if (ccBytes) {
const ccdatas = this.extractCea608Data(ccBytes);
this.cea608Parser.addData(data.samples[i].pts, ccdatas);
}
}
}
extractCea608Data (byteArray: Uint8Array): Array<number> {
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;
}
}
function canReuseVttTextTrack (inUseTrack, manifestTrack): boolean {
return inUseTrack && inUseTrack.label === manifestTrack.name && !(inUseTrack.textTrack1 || inUseTrack.textTrack2);
}
function intersection (x1: number, x2: number, y1: number, y2: number): number {
return Math.min(x2, y2) - Math.max(x1, y1);
}
export default TimelineController;