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Port Subtitle Changes from v4.7.4 (#4359) #105

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Merged
merged 1 commit into from
Sep 8, 2025
Merged

Port Subtitle Changes from v4.7.4 (#4359) #105

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71 changes: 49 additions & 22 deletions src/streaming/text/TextTracks.js
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,8 @@ function TextTracks(config) {
displayCCOnTop,
previousISDState,
topZIndex,
resizeObserver;
resizeObserver,
hasRequestAnimationFrame;

function setup() {
logger = Debug(context).getInstance().getLogger(instance);
Expand All @@ -104,6 +105,7 @@ function TextTracks(config) {
displayCCOnTop = false;
topZIndex = 2147483647;
previousISDState = null;
hasRequestAnimationFrame = ('requestAnimationFrame' in window);

if (document.fullscreenElement !== undefined) {
fullscreenAttribute = 'fullscreenElement'; // Standard and Edge
Expand Down Expand Up @@ -409,20 +411,19 @@ function TextTracks(config) {

function _renderCaption(cue) {
if (captionContainer) {
clearCaptionContainer.call(this);

const finalCue = document.createElement('div');
captionContainer.appendChild(finalCue);

previousISDState = renderHTML(
cue.isd,
finalCue,
function (src) {
return _resolveImageSrc(cue, src)
},
captionContainer.clientHeight,
captionContainer.clientWidth,
cue.isd,
finalCue,
function (src) { return _resolveImageSrc(cue, src) },
captionContainer.clientHeight,
captionContainer.clientWidth,
settings.get().streaming.text.imsc.displayForcedOnlyMode,
function (err) {
logger.info('renderCaption :', err) /*TODO: add ErrorHandler management*/
},
function (err) { logger.info('renderCaption :', err) /*TODO: add ErrorHandler management*/ },
previousISDState,
settings.get().streaming.text.imsc.enableRollUp,
settings.get().streaming.text.imsc.options
Expand All @@ -432,23 +433,26 @@ function TextTracks(config) {
}
}

function _extendLastCue(cue, track) {
if (!settings.get().streaming.text.extendSegmentedCues) {
return false;
}
if (!track.cues || track.cues.length === 0) {
// Check that a new cue immediately follows the previous cue
function _areCuesAdjacent(cue, prevCue) {
if (!prevCue) {
return false;
}
const prevCue = track.cues[track.cues.length - 1];
// Check previous cue endTime with current cue startTime
// (should we consider an epsilon margin? for example to get around rounding issues)
if (prevCue.endTime < cue.startTime) {
return prevCue.endTime >= cue.startTime;
}

// Check if cue content is identical. If it is, extend the previous cue.
function _extendLastCue(cue, prevCue) {
if (!settings.get().streaming.text.extendSegmentedCues) {
return false;
}
// Compare cues content

if (!_cuesContentAreEqual(prevCue, cue, CUE_PROPS_TO_COMPARE)) {
return false;
}
}

prevCue.endTime = Math.max(prevCue.endTime, cue.endTime);
return true;
}
Expand Down Expand Up @@ -509,7 +513,24 @@ function TextTracks(config) {
}
track.manualCueList.push(cue);
} else {
if (!_extendLastCue(cue, track)) {
// Handle adjacent cues
let prevCue;
if (track.cues && track.cues.length !== 0) {
prevCue = track.cues[track.cues.length - 1];
}

if (_areCuesAdjacent(cue, prevCue)) {
if (!_extendLastCue(cue, prevCue)) {
/* If cues are adjacent but not identical (extended), let the render function of the next cue
* clear up the captionsContainer so removal and appending are instantaneous.
* Only do this for imsc subs (where isd is present).
*/
if (prevCue.isd) {
prevCue.onexit = function () { };
}
track.addCue(cue);
}
} else {
track.addCue(cue);
}
}
Expand Down Expand Up @@ -560,7 +581,12 @@ function TextTracks(config) {
cue.onenter = function () {
if (track.mode === Constants.TEXT_SHOWING) {
if (this.isd) {
_renderCaption(this);
if (hasRequestAnimationFrame) {
// Ensure everything in _renderCaption happens in the same frame
requestAnimationFrame(() => _renderCaption(this));
} else {
_renderCaption(this)
}
logger.debug('Cue enter id:' + this.cueID);
} else {
captionContainer.appendChild(this.cueHTMLElement);
Expand All @@ -573,6 +599,7 @@ function TextTracks(config) {
}
};

// For imsc subs, this could be reassigned to not do anything if there is a cue that immediately follows this one
cue.onexit = function () {
if (captionContainer) {
const divs = captionContainer.childNodes;
Expand Down