- From: David Singer <singer@apple.com>
- Date: Wed, 15 May 2013 13:07:27 -0700
- To: John Kemp <john@jkemp.net>
- Cc: John Foliot <john@foliot.ca>, 'Loretta Guarino Reid' <lorettaguarino@google.com>, public-texttracks@w3.org
On May 15, 2013, at 12:57 , John Kemp <john@jkemp.net> wrote: >>> David, I would >>> hope we would also be ensuring that SMPTE-TT would also be "convertible" >>> within the same mapping effort. > > SMPTE-TT is a profile of W3C TTML (https://www.smpte.org/sites/default/files/st2052-1-2010.pdf). One of its main uses is to allow the "tunneling" of broadcast TV closed captions (CEA 608) as binary data, base64-encoded in the TTML, a sort of compatibility or translation mode. > > Is the intent either to allow others (like SMPTE) to profile VTT (in the same way that SMPTE profiled TTML), or to define this kind of compatibility mode in VTT? The intention is to find those features of TTML that map into VTT, so that one can say "if you author this way, it's convertible 'without loss' into VTT", and so on. So, it might inform a discussion of TTML profiles, but no, VTT itself is not profiled nor expected to be. > > Regards, > > JohnK > > On May 15, 2013, at 3:43 PM, John Foliot wrote: > >> David Singer wrote: >>> On May 15, 2013, at 12:29 , Loretta Guarino Reid >>> <lorettaguarino@google.com> wrote: >>> >>>> I'm not entirely sure what this means, but "using TTML as a source >>> format for WebVTT" sounds scary. >>> >>> maybe badly expressed by me. One ought to be able to convert TTML to >>> VTT. We've had a long-standing action to define how that's done. TTML >>> is an authoring/exchange format by design, so it ought to be possible >>> and needs defining. >> >> +1 to David. >> >> Loretta TTML is essentially XML (Sean Hayes will correct me, but in >> principle, ya, it is XML-ish), and so converting XML-marked content to >> another "markup format" is a common occurrence already today. David, I would >> hope we would also be ensuring that SMPTE-TT would also be "convertible" >> within the same mapping effort. >> >> At this point I would also express positive support for working with the >> Timed Text WG as proposed. >> >> JF >> >> > David Singer Multimedia and Software Standards, Apple Inc.
Received on Wednesday, 15 May 2013 20:07:59 UTC