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Re: [whatwg] How to expose caption tracks without TextTrackCues

From: Brendan Long <self@brendanlong.com>
Date: Mon, 03 Nov 2014 10:56:48 -0600
Message-ID: <5457B3D0.3060506@brendanlong.com>
To: whatwg@lists.whatwg.org

On 10/27/2014 08:43 PM, Silvia Pfeiffer wrote:
> On Tue, Oct 28, 2014 at 2:41 AM, Philip J├Ągenstedt <philipj@opera.com> wrote:
>> On Sun, Oct 26, 2014 at 8:28 AM, Silvia Pfeiffer
>> <silviapfeiffer1@gmail.com> wrote:
>>> On Thu, Oct 23, 2014 at 2:01 AM, Philip J├Ągenstedt <philipj@opera.com> wrote:
>>>> On Sun, Oct 12, 2014 at 11:45 AM, Silvia Pfeiffer
>>>> <silviapfeiffer1@gmail.com> wrote:
>>>>> Using the VideoTrack interface it would list them as a kind="captions"
>>>>> and would thus also be able to be activated by JavaScript. The
>>>>> downside would that if you have N video tracks and m caption tracks in
>>>>> the media file, you'd have to expose NxM videoTracks in the interface.
>>>> VideoTrackList can have at most one video track selected at a time, so
>>>> representing this as a VideoTrack would require some additional
>>>> tweaking to the model.
>>> The "captions" video track is one that has video and captions rendered
>>> together, so you only need the one video track active. If you want to
>>> turn off captions, you merely activate a different video track which
>>> is one without captions.
>>>
>>> There is no change to the model necessary - in fact, it fits perfectly
>>> to what the spec is currently describing without any change.
>> Ah, right! Unless I'm misunderstanding again, your suggestion is to
>> expose extra video tracks with kind captions or subtitles, requiring
>> no spec change at all. That sounds good to me.
> Yes, that was my suggestion for dealing with UA rendered tracks.
Doesn't this still leave us with the issue: "if you have N video tracks
and m caption tracks in
the media file, you'd have to expose NxM videoTracks in the interface"?
We would also need to consider:

  * How do you label this combined video and text track?
  * What is the track's "id"?
  * How do you present this to users in a way that isn't confusing?
  * What if the video track's kind isn't "main"? For example, what if we
    have a sign language track and we also want to display captions?
    What is the generated track's kind?
  * The "language" attribute could also have conflicts.
  * I think it might also be possible to create files where the video
    track and text track are different lengths, so we'd need to figure
    out what to do when one of them ends.
Received on Monday, 3 November 2014 16:57:15 UTC

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