W3C home > Mailing lists > Public > public-tt@w3.org > January 2014

Re: WebVTT endTime = infinity and ability to rewrite cue times

From: John Birch <John.Birch@screensystems.tv>
Date: Tue, 14 Jan 2014 22:09:27 +0000
To: "'self@brendanlong.com'" <self@brendanlong.com>, "'public-tt@w3.org'" <public-tt@w3.org>
Message-ID: <0981DC6F684DE44FBE8E2602C456E8AB014F6BB1BF@SS-IP-EXMB-01.screensystems.tv>
We had concerns in EBU-TT about an every growing doc. Particularly for xml and completeness / validation :-) I guess in webVTT YMMV ;-)


From: Brendan Long [mailto:self@brendanlong.com]
Sent: Tuesday, January 14, 2014 10:49 PM
To: public-tt@w3.org <public-tt@w3.org>
Subject: Re: WebVTT endTime = infinity and ability to rewrite cue times

On Tue, 2014-01-14 at 21:37 +0000, John Birch wrote:
In EBU-TT the proposal for live is to use a single document per subtitle and avoid dependencies on Id values... Only one document is allowed to be valid in the decoder at any one time so the new document automatically replaces the old one.
I guess we could completely replace the WebVTT document for every cue, but it seems like it would be less efficient and harder to implement. It would be really nice if we could download one file and parse it as we receive it, with no need to do polling or restarting the parser. Having everything in one document is also convenient for implementations using GStreamer, but I'm not sure if that would apply to other media frameworks.

Wrt to end time it might be better to set an end time some reasonable point in the future (e.g. 10 or 20 seconds) to avoid the problem of a hanging subtitle if the revised cue never gets sent (e.g. Service switch)
That's a good point. Maybe infinity isn't what we want anyway. I'll bring this up with my coworkers.
John Birch | Strategic Partnerships Manager | Screen
Main Line : +44 1473 831700 | Ext : 270 | Direct Dial : +44 1473 834532
Mobile : +44 7919 558380 | Fax : +44 1473 830078
John.Birch@screensystems.tv<mailto:John.Birch@screensystems.tv> | www.screensystems.tv<http://www.screensystems.tv> | https://twitter.com/screensystems

Visit us at
BVE, Excel London, 25-27 February 2014, Stand M15

P Before printing, think about the environment

This message may contain confidential and/or privileged information. If you are not the intended recipient you must not use, copy, disclose or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation. Screen Subtitling Systems Ltd. Registered in England No. 2596832. Registered Office: The Old Rectory, Claydon Church Lane, Claydon, Ipswich, Suffolk, IP6 0EQ
Received on Tuesday, 14 January 2014 22:09:57 UTC

This archive was generated by hypermail 2.3.1 : Thursday, 5 October 2017 18:24:13 UTC