[Bug 24382] New: <track> missed cues fail to reach the application & show difficulty of identifying which cues triggered the cuechange event

https://www.w3.org/Bugs/Public/show_bug.cgi?id=24382

            Bug ID: 24382
           Summary: <track> missed cues fail to reach the application &
                    show difficulty of identifying which cues triggered
                    the cuechange event
           Product: WHATWG
           Version: unspecified
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: HTML
          Assignee: ian@hixie.ch
          Reporter: silviapfeiffer1@gmail.com
        QA Contact: contributor@whatwg.org
                CC: b.lund@cablelabs.com,
                    cyril.concolato@telecom-paristech.fr,
                    david.lewis4@bbc.co.uk, mike@w3.org,
                    oipfjon@gmail.com, philipj@opera.com,
                    public-html-admin@w3.org,
                    public-html-wg-issue-tracking@w3.org,
                    silviapfeiffer1@gmail.com
        Depends on: 24161

The "time marches on" algorithm for media playback will trigger the oncuechange
event for cues that are entered or exited. After that it is possible to
identify which cues are active among all the cues in a TextTrack by looking at
.activeCues and .cues in the TextTrack object.

Short cues (less than 250ms long) may be missed by the "time marches on"
algorithm, yes still cause a oncuechange event (since they have been entered
and exited). It is, however, not possible from looking at .activeCues and .cues
to identify these cues.

Other than registering an onenter and onexit event on every cue, determining
those missed cues is hard. Going through the list of all cues and determining
which cues have just been passed and are short is more heuristics than a proper
approach.

There is more discussion of this in Bug #24161 with a suggestion to introduce a
missedCues attribute on the TextTrack interface.

Another option would be to make the cuechange event a CustomEvent with a
TextTrackCueList that contains the list of cues that triggered the cuechange
event.

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Received on Friday, 24 January 2014 11:06:45 UTC