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Re: ISSUE-332 (-): #cellResolution support [TTML IMSC 1.0]

From: Pierre-Anthony Lemieux <pal@sandflow.com>
Date: Tue, 23 Sep 2014 15:40:53 -0700
Message-ID: <CAF_7JxB9O3uZkaS9OYgJPzeituhW2xgWJP5BYRpHmoDoGGR0OQ@mail.gmail.com>
To: Timed Text Working Group <public-tt@w3.org>
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

Best,

-- Pierre

On Thu, Aug 7, 2014 at 5:22 AM, Timed Text Working Group Issue Tracker
<sysbot+tracker@w3.org> wrote:
> ISSUE-332 (-): #cellResolution support [TTML IMSC 1.0]
>
> http://www.w3.org/AudioVideo/TT/tracker/issues/332
>
> Raised by: Frans de Jong
> On product: TTML IMSC 1.0
>
> ------------------
> Request
> ------------------
> Chapter 4.8 (Common Constraints -> Features)
>
> The part:
>
> "#cellResolution  SHALL NOT be used."
>
> should be deleted.
>
> ------------------
> 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.
>
> --------------------------
> 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.
>
> -------------------
> 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.
>
>
>
>
Received on Tuesday, 23 September 2014 22:41:42 UTC

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