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TTML support #111

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sirkro opened this issue Jun 24, 2015 · 5 comments
Closed

TTML support #111

sirkro opened this issue Jun 24, 2015 · 5 comments
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status: archived Archived and locked; will not be updated type: enhancement New feature or request
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@sirkro
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sirkro commented Jun 24, 2015

In the latest release of DashJS (1.4.0), they added support for TTML.

It would be perfect if support for TTML could be added to Shaka-player.

Teststream: http://dash.edgesuite.net/dash264/TestCases/4b/qualcomm/1/ED_OnDemand_5SecSeg_Subtitles.mpd

<AdaptationSet mimeType="application/ttml+xml" lang="en">
      <Role schemeIdUri="urn:mpeg:dash:role" value="subtitle" />
      <Representation id="7"  bandwidth="268" >
        <BaseURL>English_track.xml</BaseURL>
      </Representation>
    </AdaptationSet>
      <AdaptationSet mimeType="application/ttml+xml" lang="ge">
      <Role schemeIdUri="urn:mpeg:dash:role" value="subtitle" />
      <Representation id="8"  bandwidth="268" >
        <BaseURL>German_track.xml</BaseURL>
      </Representation>
    </AdaptationSet>
@joeyparrish joeyparrish added the type: enhancement New feature or request label Jun 26, 2015
@joeyparrish
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Thanks for the request. At the moment, we rely on the browser's subtitle support. On Chrome or Firefox, Shaka Player will do WebVTT.

For context, Shaka Player has made a point of not doing any DOM manipulation or CSS so far. Both of those things would have to change in order for us to render any subtitle format not directly supported by the browser. It's doable, but would require some architectural changes first.

We can't fit this into our schedule right now, but we'll keep it in mind.

@sanbornhilland
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Related to this and a possible alternative for some people, how difficult would it be to add an option to sidecar load WebVTT subtitles?

@tdrews
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tdrews commented Jul 22, 2015

Please see #133 for a separate discussion on sidecar loading (outside of the MPD) WebVTT subtitles.

@tdrews tdrews added this to the v1.6.0 milestone Aug 6, 2015
@joeyparrish joeyparrish modified the milestones: v1.6.0, Future Aug 21, 2015
@natalieharris natalieharris self-assigned this Jan 4, 2016
shaka-bot pushed a commit that referenced this issue Jun 22, 2016
Otherwise, we fail to play manifests containing TTML.  Without a TTML
parser, TTML streams should be ignored and not cause failures.

Issue #111

Change-Id: I982ad04083e40a3f5c5023f0059fa4ae1604ab07
shaka-bot pushed a commit that referenced this issue Jun 23, 2016
Issue #111

Change-Id: Ifb1dde142c8acee5a2e67b8a76ddea743af957d3
shaka-bot pushed a commit that referenced this issue Jun 28, 2016
This adds support for TTML in XML form only.  TTML embedded in MP4 will
be added later.

Issue #111

Change-Id: Ic44cbcc57c6105c398778e676565f2511bfd8a73
shaka-bot pushed a commit that referenced this issue Jul 7, 2016
Issue #111

Change-Id: Ia9ebcd9be19ebdc452d9554ace116265d5a7d59c
@dougdoe
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dougdoe commented Jul 8, 2016

Hi, my team is watching this issue. I have a couple of questions that I hope you can answer to help me plan:

  1. Are you implementing TTML 1 or TTML 2 support? I don't see references to TTML 2, so I assume you are following the TTML 1 Specification. Is that right?
  2. Does this work include support for chunked TTML for Live streams?

@joeyparrish
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Hi Doug,

  1. We are implementing partial TTML 1 support. We are using the TTML 1 spec, but we are only implementing what can be represented in the browser's native cues interface. The means we can't implement extents or origins based on pixel sizes, animation, etc.
  2. Shaka v2 betas already support chunked/segmented subtitles, but only in the specific formats we parse. Currently, that's the textual forms of WebVTT and TTML. We do not yet support text streams embedded in MP4 (Segmented WebVTT in MP4 #277 and Segmented TTML in MP4 #278).

One important note about segmented text is that just like audio and video, segments must exist to cover the entire period. If there are no cues to display during a given segment's time, the segment would be a valid WebVTT or TTML file, but would contain no cues.

shaka-bot pushed a commit that referenced this issue Jul 11, 2016
Issue #111.

Change-Id: Ieeafda794b54ae2aad6751eadba28e28882d6b49
@shaka-project shaka-project locked and limited conversation to collaborators Mar 22, 2018
@shaka-bot shaka-bot added the status: archived Archived and locked; will not be updated label Apr 15, 2021
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