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Support CEA-608 embedded in video representations in DASH #2362

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ojw28 opened this issue Jan 23, 2017 · 6 comments
Closed

Support CEA-608 embedded in video representations in DASH #2362

ojw28 opened this issue Jan 23, 2017 · 6 comments

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@ojw28
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ojw28 commented Jan 23, 2017

As per title.

@Natarajan92
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Natarajan92 commented Jan 24, 2017

Hi ojw28,

As you marked it as enhancement , the updated version of Exo-Player will support embedded CEA-608 captions of video in Dash Streaming ?

According to Dash-IF-IOP document, we use to signal the CEA-608 in manifest file as follows

<Accessibility schemeIdUri="urn:scte:dash:cc:cea-608:2015"/>

Will it display CC by using updated version of Exo-Player ?

@ojw28
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ojw28 commented Jan 24, 2017

That's the intention, yes. We're not promising to add support, but it's something we're actively looking at. This issue will be used to track any work in this area. If we do add support, it's likely that we will require the Accessibility element to be present in the AdaptationSet for CEA-608 to be enabled. It sounds like you're already adding it.

It would be preferable, although likely not required, if you could also fill out the value of the Accessibility element to indicate the language (and multiple channels, if applicable). This is described in the DASH-IF-IOP document also.

@ojw28
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ojw28 commented Jan 24, 2017

Specifically, the most useful thing for the client would be if you used values of the form:

CC1=eng;CC3=deu

ojw28 added a commit that referenced this issue Jan 24, 2017
Issue: #2362

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145401668
ojw28 added a commit that referenced this issue Jan 24, 2017
Issue: #2362

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145402640
ojw28 added a commit that referenced this issue Jan 25, 2017
- Fix to use different track ids for EMSG + CEA608, so they can
  both be enabled at once.
- Tweaked extractor to output formats prior to endTracks() when
  parsing the initial moov box. This makes it easier to handle
  multiple tracks through the chunk package. It may or may not
  be made a requirement (it's already true for the MKV extractor).

Issue: #2362
Issue: #2176

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145538757
ojw28 added a commit that referenced this issue Feb 15, 2017
Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146243681
ojw28 added a commit that referenced this issue Feb 23, 2017
Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148216614
ojw28 added a commit that referenced this issue Feb 28, 2017
This change exposes declared CEA-608 and EMSG tracks. The
tracks currently provide no samples.

Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148390849
ojw28 added a commit that referenced this issue Feb 28, 2017
Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148764237
ojw28 added a commit that referenced this issue Mar 10, 2017
Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=149524412
ojw28 added a commit that referenced this issue Mar 10, 2017
I think it's likely we'll revert back to discarding media
in sync with the playback position for ExtractorMediaSource
and HlsMediaSource too, where the tracks are muxed with ones
we're requesting anyway.

Note: discardBuffer is named as it is because it'll also be
used to discard for enabled tracks soon, as a result of the
remaining TODO in ChunkSampleStream. For enabled tracks the
discard will also be conditional on the samples having been
consumed, obviously.

Issue: #2362
Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=149525857
@ojw28
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ojw28 commented Mar 12, 2017

This functionality should be working now in dev-v2. Please give it a try.

There's still one technical issue where events might go missing when seeking short distances and/or toggling the cea-608 tracks on and off, so the issue is kept open to track fixing that. It's unlikely to be much of an issue in practice, however.

@Natarajan92
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Ok! I will give a try and let you know . Thanks

@ojw28
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ojw28 commented Mar 16, 2017

Marking as fixed. We'll track the remaining minor issue separately.

@ojw28 ojw28 closed this as completed Mar 16, 2017
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