ISSUE-332: #cellResolution support
#cellResolution support
#cellResolution support
- State:
- CLOSED
- Product:
- TTML IMSC 1.0
- Raised by:
- Frans de Jong
- Opened on:
- 2014-08-07
- Description:
- ------------------
Request
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Chapter 4.8 (Common Constraints -> Features)
The part:
"#cellResolution SHALL NOT be used."
should be deleted.
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Reasoning
------------------
IMSC currently does not allow the use of the feature #cellResolution
https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml-ww-profiles/ttml-ww-profiles.html#features
It is not sufficient that an IMSC processor processes the EBU-TT-D document but ignores cellResolution values. Indirectly the cellResolution defines the fontSize. IMSC calculates the fontSize in percentages with an implicit cellResolution (with the TTML initial value, "32 15"). EBU-TT-D documents (example here: http://tech.ebu.ch/docs/ebu-tt/ebu-tt-d-imsc-compliance-example.xml ) will renderin a different font-size and therefore intended line breaks cannot be guaranteed. In this use case this is not acceptable for the broadcaster.
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General use case
-------------------------
A german broadcaster uses an EBU-TT-D document (https://tech.ebu.ch/docs/ebu-tt/ebu-tt-d-imsc-compliance-example.xml) for HbbTV subtitles and for their catch up tv - portal for PC. Both the HbbTV application (or in the future the HbbTV 2.0 compliant device) and the player of the EBU-TT-D portal support EBU-TT-D. Now the broadcaster licences the same AV content together with the subtitles to a commercial on-demand Internet streaming media provider. The provider distributes its content to a client which is conformant to IMSC 1.0 (IMSC 1.0 Text - http://www.w3.org/ns/ttml/profile/imsc1/text). Conformance to EBU-TT-D of this player is not documented.
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Requirement
-------------------
The broadcaster demands from the provider that the subtitles will be displayed as specified in the EBU-TT-D file. The provider will distribute the EBU-TT-D file as it is provided and will not convert the EBU-TT-D file.
- Related Actions Items:
- No related actions
- Related emails:
- {agenda} TTWG Meeting 25/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-24)
- Re: ISSUE-332 (-): #cellResolution support [TTML IMSC 1.0] (from pal@sandflow.com on 2014-09-23)
- Re: {minutes} TTWG Meeting 11/9/2014 (from silviapfeiffer1@gmail.com on 2014-09-13)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from nigel.megitt@bbc.co.uk on 2014-09-12)
- Re: {minutes} TTWG Meeting 11/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-12)
- Re: {minutes} TTWG Meeting 11/9/2014 (from silviapfeiffer1@gmail.com on 2014-09-12)
- Re: {minutes} TTWG Meeting 11/9/2014 (from silviapfeiffer1@gmail.com on 2014-09-12)
- Re: {minutes} TTWG Meeting 11/9/2014 (from ckennedy@apple.com on 2014-09-11)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from John.Birch@screensystems.tv on 2014-09-11)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from pal@sandflow.com on 2014-09-11)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from nigel.megitt@bbc.co.uk on 2014-09-11)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from pal@sandflow.com on 2014-09-11)
- {minutes} TTWG Meeting 11/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-11)
- Re: IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from John.Birch@screensystems.tv on 2014-09-11)
- IMSC 1 re: ISSUE-332, ISSUE-342 and ISSUE-339 (from pal@sandflow.com on 2014-09-10)
- Re: {agenda} TTWG Meeting 11/9/2014 (from glenn@skynav.com on 2014-09-10)
- {agenda} TTWG Meeting 11/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-10)
- {agenda} TTWG Meeting 4/9/2014 (from nigel.megitt@bbc.co.uk on 2014-09-03)
- {agenda} TTWG Meeting 21/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-20)
- Re: New Change Proposal 28 on IMSC 1: Profile refactoring (from nigel.megitt@bbc.co.uk on 2014-08-14)
- Re: New Change Proposal 28 on IMSC 1: Profile refactoring (from pal@sandflow.com on 2014-08-14)
- {agenda} TTWG Meeting 14/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-13)
- New Change Proposal 28 on IMSC 1: Profile refactoring (from nigel.megitt@bbc.co.uk on 2014-08-08)
- Re: {minutes} TTWG Meeting 7/8/2014 (from glenn@skynav.com on 2014-08-07)
- {minutes} TTWG Meeting 7/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-07)
- ISSUE-332 (-): #cellResolution support [TTML IMSC 1.0] (from sysbot+tracker@w3.org on 2014-08-07)
Related notes:
See also Change Proposal 28 [1] which helps enable this change to be implemented by removing the strong requirement to meet the HRM constraints: the proposal in this issue does not consider any impact on complexity.
[1] https://www.w3.org/wiki/TTML/changeProposal028
Addressed at [2] per [1]
[1] https://dvcs.w3.org/hg/ttml/rev/7084721154b6
[2] http://lists.w3.org/Archives/Public/public-tt/2014Sep/0031.html
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