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Re: Updated Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.

From: Andreas Tai <tai@irt.de>
Date: Wed, 31 Oct 2012 18:53:51 +0100
Message-ID: <509165AF.6020306@irt.de>
To: John Birch <John.Birch@screensystems.tv>
CC: "Monica Martin (MS OPEN TECH)" <momartin@microsoft.com>, Michael Dolan <mdolan@newtbt.com>, "public-tt@w3.org" <public-tt@w3.org>
Hi Monica, Hi John,

It´s true that the increase of the character limitation from 32 to 38 
does not cover all subtitle presentation formats in Europe but with 
"european teletext" a good proportion of it. Furthermore the 32 
character limitation is related to CEA-608 and the WS Teletext can be 
seen as an European equivalent. Apart from subtitle content that comply 
with the 38 character constraint this limit is also a well-known 
restriction in Europe.

To summarize: the change may not solve every issue but it would 
facilitate the distribution of European content in the US and therefore 
will be a good thing.

If this benefit does outbalance changes that have to be made in the 
SDP-US (e.g. add a new font-size value) or negative side effects on the 
main purpose of the delivery profile is a different question and has to 
be decided by the WG.

Best regards,

Andreas

Am 25.10.2012 18:38, schrieb John Birch:
> Thanks,
>
> Whilst I have no issue with creating a constrained definition for both the content and the decoder to encourage the implementation of support in browsers and CE devices for captioning (accessibility), I do have significant reservations about the concept of similar constraints being considered appropriate in an IMF for subtitling.
>
> Best regards,
> John
>
>
> John Birch | Screen Systems | Strategic Partnerships Manager
> Main Line : +44 1473 831700 | Ext : 270 | Direct Dial : +44 1473 834532
> Mobile : +44 7919 558380 | Fax : +44 1473 830078
> John.Birch@screensystems.tv | www.screensystems.tv | https://twitter.com/screensystems
>
> Visit us at
> SMPTE Annual Technical Conference & Exhibition,23-24 October, Stand 112
> Loews Hollywood hotel, Hollywood
>
> P Before printing, think about the environment-----Original Message-----
> From: Monica Martin (MS OPEN TECH) [mailto:momartin@microsoft.com]
> Sent: 25 October 2012 16:49
> To: John Birch; Michael Dolan; public-tt@w3.org; Andreas Tai (tai@irt.de)
> Subject: RE: Updated Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> We'll review this John. Adding Andreas Tai who input to the proposal for EBU and their tele-text requirements.
>
> Monica
>
> -----Original Message-----
> From: John Birch [mailto:John.Birch@screensystems.tv]
> Sent: Thursday, October 25, 2012 8:43 AM
> To: Monica Martin (MS OPEN TECH); Michael Dolan; public-tt@w3.org
> Subject: RE: Updated Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> I seek clarification....
>
> Does the revised limit of 38 characters only apply to the Simple Delivery Protocol?
>
> I believe there may be some confusion regarding current European subtitling practice.
>
> EBU TR 3264 does not have a specific line limitation, in effect a line can be the size of a TTI block within an STL file....
>
>          The Text Field contains all, or some of, the text and control characters to convey a subtitle. It has a
>          fixed length of 112 bytes and may contain any valid character code selected from the character code table
>          specified in the CCT field of the GSI block.
>          Regardless of which character code table is in use, the following conventions must be applied:
>          - the CR/LF indicator, used to initiate the second and subsequent rows of the subtitle display, is
>          conveyed by character code 8Ah;
>          - the Text Field of the last TTI block of a subtitle must always terminate with code 8Fh;
>          - unused space in the Text Field will be set to 8Fh..
>
> The practical limitation in an STL subtitle file USED FOR TELETEXT presentation is 38 characters, although typically this will be 37 or 36 characters to allow for double height and or coloured text.
>
> However, many STL files are used in non Teletext modes, consequently this practical downstream limitation does not apply...
> DVB subtitles are frequently longer than 45 characters per line, especially in certain languages (e.g. Italian).
> Further, STL subtitle files are not the only format used as the origination content for European subtitles, I would estimate their application to be about 30-40%.
>
> I am very concerned that the SMPTE-TT (SDP) standard could become an inappropriate 'lower common denominator' particularly since it has been adopted for use within IMF.
> This would not fit the large proportion of CURRENT European practise as it should be appreciated that Teletext subtitling is deprecated... most broadcasters have moved to DVB subtitling.
>
> Other proposed limitations (for example number of regions) also do not fit well with European practises.
>
> With regards,
>
> John
>
> John Birch | Screen Systems | Strategic Partnerships Manager Main Line : +44 1473 831700 | Ext : 270 | Direct Dial : +44 1473 834532 Mobile : +44 7919 558380 | Fax : +44 1473 830078 John.Birch@screensystems.tv | www.screensystems.tv | https://twitter.com/screensystems
>
> Visit us at
> SMPTE Annual Technical Conference & Exhibition,23-24 October, Stand 112 Loews Hollywood hotel, Hollywood
>
> P Before printing, think about the environment-----Original Message-----
> From: Monica Martin (MS OPEN TECH) [mailto:momartin@microsoft.com]
> Sent: 25 October 2012 09:16
> To: Michael Dolan; public-tt@w3.org
> Subject: RE: Updated Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> Updated proposal to close Issue-192
>
> Updated proposal addresses EBU requirements for display of European content in the US and the concerns raised about 16-9 display formats.
>
> Change from: At most 32 characters must be present in any displayed text line.
> Change to: No more than 38 characters MUST be present in any displayed text line where the aspect ratio of the root container is 4:3 and no more than 42 characters MUST be present for 16:9.
>
> Also add these 2 new requirements:
> The total character limit for displayed text should be 152 where the aspect ratio of the root container is 4:3.
> The total character limit for displayed text should be 168 where the aspect ratio of the root container is 16:9.
>
> Add a note following the requirements:
> These requirements accommodate European content that is to be displayed in the US.
>
> Thanks.
>
> Monica J Martin
> Senior Program Manager
> Microsoft Open Technologies, Inc.
> A subsidiary of Microsoft Corporation
>
>
> -----Original Message-----
> From: Michael Dolan [mailto:mdolan@newtbt.com]
> Sent: Wednesday, October 17, 2012 11:16 PM
> To: public-tt@w3.org
> Subject: RE: Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> I think this is not a general solution since it does not address other display aspect ratios, such as 21:9, which is becoming more common, and it is silent on every other aspect ratio.
>
> Also, with the change to SHOULD, this allows unlimited characters/line on 4:3, which I don't think was intended.
>
> An informative note should be added to state that the cellResolution needs to set accordingly since the initial TTML attribute value force 32x15 no matter what the display aspect ratio is.
>
> This needs further discussion, think.
>
>          Mike
>
> -----Original Message-----
> From: Monica Martin (MS OPEN TECH) [mailto:momartin@microsoft.com]
> Sent: Wednesday, October 17, 2012 9:53 PM
> To: 'public-tt@w3.org'; Michael Jordan (mijordan@adobe.com)
> Subject: Proposal for ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> Here is a draft proposal for Issue-192 and Action-114 on R0041.
>
> Change from: At most 32 characters must be present in any displayed text line.
> Change to: No more than 32 characters SHOULD be present in any displayed text line where the aspect ratio of the root container is 4:3 and no more than 42 characters MUST be present for 16:9.
>
> Monica
>
> -----Original Message-----
> From: Timed Text Working Group Issue Tracker [mailto:sysbot+tracker@w3.org]
> Sent: Thursday, October 11, 2012 7:22 AM
> To: public-tt@w3.org
> Subject: ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> ISSUE-192: R0041 doesn't allow for EBT-TT conversion easily. Revise R0041 to a SHOULD.
>
> http://www.w3.org/AudioVideo/TT/tracker/issues/192
>
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Andreas Tai
Production Systems Television IRT - Institut fuer Rundfunktechnik GmbH
R&D Institute of ARD, ZDF, DRadio, ORF and SRG/SSR
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Phone: +49 89 32399-389 | Fax: +49 89 32399-200
http: www.irt.de | Email: tai@irt.de
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Received on Wednesday, 31 October 2012 18:24:34 GMT

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