add comments for duplicated cues check

hongsw · May 2, 2017 · 4ff21ec · 4ff21ec
1 parent 06610e2
commit 4ff21ec
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Showing 2 changed files with 6 additions and 0 deletions.
diff --git a/src/controller/timeline-controller.js b/src/controller/timeline-controller.js
@@ -277,6 +277,9 @@ class TimelineController extends EventHandler {
         WebVTTParser.parse(payload, this.initPTS, vttCCs, frag.cc, function (cues) {
             // 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 (!textTracks[frag.trackId].cues.getCueById(cue.id)) {
                 textTracks[frag.trackId].addCue(cue);
               }

diff --git a/src/utils/webvtt-parser.js b/src/utils/webvtt-parser.js
@@ -90,6 +90,9 @@ const WebVTTParser = {
 
             cue.startTime += cueOffset - localTime;
             cue.endTime += cueOffset - localTime;
+
+            // Create a unique hash id for a cue based on start/end times and text.
+            // This helps timeline-controller to avoid showing repeated captions.
             cue.id = hash(cue.startTime) + hash(cue.endTime) + hash(cue.text);
 
             // Fix encoding of special characters. TODO: Test with all sorts of weird characters.