- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Sat, 7 Aug 2010 16:08:35 +1000
- To: Sean Hayes <Sean.Hayes@microsoft.com>
- Cc: Geoff Freed <geoff_freed@wgbh.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>, Judy Brewer <jbrewer@w3.org>
- Message-ID: <AANLkTinYQb7Mf_V+j8h1NNALHqZif+0jWWGJrCKqFhvf@mail.gmail.com>
On Sat, Aug 7, 2010 at 2:24 AM, Sean Hayes <Sean.Hayes@microsoft.com> wrote: > > > “WebSRT by the WHATWG is already capable of supporting almost all of TTML, > so I am not worried about this.” > > I don’t think this is true. WebSRT doesn’t for example doesn’t support > arbitrary positioning of multiple captions in the video rectangle at the > same time. TTML is a superset of WebSRT in terms of functionality. > It actually does. If you read up on http://www.whatwg.org/specs/web-apps/current-work/complete/rendering.html#timed-tracks-0, it clearly deals with multiple captions at the same time and WebSRT allows for such. > However I’ve looked at what Ian is up to recently, and I think that TTML > could map fairly well into his evolving architecture, so all we need to make > sure is that he doesn’t explicitly rule it out. > I also would prefer to keep the <track> platform open to any file format. Though I do believe we need a baseline format that all browsers implement. What happens on top of that can be flexible. > He has special cased a bunch of stuff because of his insistence that WebSRT > is all that is needed, but I think that might be straightened out, if it > ever gets proposed back into the HTML process, and assuming that he is open > to technical feedback. > I'm trying to give technical feedback now also. Cheers, Silvia. > *From:* public-html-a11y-request@w3.org [mailto: > public-html-a11y-request@w3.org] *On Behalf Of *Silvia Pfeiffer > *Sent:* 06 August 2010 01:07 > *To:* Geoff Freed > *Cc:* HTML Accessibility Task Force; Judy Brewer > *Subject:* Re: text-format discussion from today's call > > > > Hi Geoff, > > This is all very interesting indeed. > > I do wonder, however, how much "automatism" can be in there from saying > because "SMPTE is using TTML as their transcoding format for IP delivery of > captions" to saying "TTML also has to be supported by the Web". The problem > about this statement is implementation support in Web browsers. If no Web > browser is implementing support for TTML, TTML will not mean much on the > Web, no matter how many TTML documents exist from repurposed broadcast > captions. > > But, to be honest, I do not see that as a big problem. Transcoding from one > text format to another is not a big issue where those formats support the > same functionality. I believe that whatever format will be chosen for HTML5, > it will support all the TTML features, so there should be no problem in > transcoding. In fact, even the proposed draft WebSRT by the WHATWG is > already capable of supporting almost all of TTML, so I am not worried about > this. > > In fact, if I was a broadcaster, I would probably just create both file > types from my existing broadcast captions and use them as appropriate. It > has been done with video before and is a much bigger problem there since > transcoding in video means data loss. This is not the case for text, so > won't be much of an issue, IMHO. > > But, you are right, it is good to know these things and to make sure they > are compatible. Thanks for sharing! > > Regards, > Silvia. > > On Fri, Aug 6, 2010 at 2:52 AM, Geoff Freed <geoff_freed@wgbh.org> wrote: > > > Greetings, all: > > Regarding the conversation on the call today about timed-text formats, I’d > like to offer some further thoughts regarding the format eventually > recommended by the a11y group and/or HTML5 and how it may affect others. At > a minimum these comments may further complicate matters. Sorry... > > Some on the list may be aware that SMPTE (Society of Motion Picture and > Television Engineers) is coming close to completing a standard for the > repurposing of broadcast captions for IP delivery. This standard, called > SMPTE-TT, is based almost entirely on TTML. SMPTE-TT will provide > broadcasters a clearly defined method for converting huge libraries of > existing captions for Web delivery. > > Many here may also be aware of legislation making its way through the U.S. > Congress that will, in some form, mandate the inclusion of captions and > descriptions on some types of video material on the Web, most likely related > to material that originates in the broadcast sphere and is then transferred > to the Web. The U.S. House of Representatives passed its version of the > bill (HR3101, The 21st-Century Communications and Video Accessibility Act; > http://www.coataccess.org/node/9733) last week, and the Senate is still > debating its version but is expected to complete its work soon. > > Among its many provisions, HR3101 contains the following language: > > ============ > (1) CLOSED-CAPTIONING REPORT.—Within 6 months after the date of the first > meeting of the Advisory Committee, the Advisory Committee shall develop and > submit to the Commission a report that includes the following: > > (A) An identification of the performance objectives for protocols, > technical capabilities, and technical procedures needed to > permit content providers, content distributors, Internet service providers, > software developers, and device manufacturers to > reliably encode, transport, receive, and render closed captions of video > programming delivered using Internet protocol. > > (B) An identification of additional protocols, technical capabilities, and > technical procedures beyond those available as of the > date of enactment of this Act for the delivery of closed captions of video > programming delivered using Internet protocol that > are necessary to meet the performance objectives identified under > subparagraph (A). > > (C) A recommendation for any regulations that may be necessary to ensure > compatibility between video programming > delivered using Internet protocol and devices capable of receiving and > displaying such programming in order to facilitate > access to closed captions. > ============ > > C is most relevant here: it’s stating that the committee must recommend a > format for IP delivery of captions. The committee specified in (1) will > probably have significant representation from the broadcast world, and my > educated guess is that broadcasters are probably going to push for SMPTE-TT > as the standard to specify in the regulations. If there is a disconnect > between this recommendation and what is recommended in HTML5, it could > create a significant headache for the broadcast industry. In short, > harmonization of the text-display formats would be ideal. > > It’s important to keep this specific issue in mind while debating the > text-format problem, and I raise it just to remind everyone that a good deal > of video on the Web, especially captioned video, originates elsewhere and > will continue to do so for some time. The amount of captioned programming > repurposed from the broadcast world is significant, and we should be paying > close attention to what is happening there. Broadcasters will probably > favor a single conversion format for captions from terrestrial/cable to Web. > In other words, if they’re already having to convert from CEA-608/708 to > SMPTE-TT (not a done deal), they’re probably not going to want to do another > conversion, with potentially different results or limitations, to whatever > format is recommended by HTML5 and its implementers. > > Discuss. > > Thanks. > Geoff/NCAM > > > >
Received on Saturday, 7 August 2010 06:09:28 UTC