W3C home > Mailing lists > Public > public-tt@w3.org > March 2015

[VTT] review from a member of the CSS WG

From: David Singer <singer@apple.com>
Date: Mon, 30 Mar 2015 14:35:57 -0700
Cc: public-texttracks@w3.org, Alan Stearns <stearns@adobe.com>
Message-id: <B394E0D3-1547-4552-90B5-8CAD0087B888@apple.com>
To: Public TTWG List <public-tt@w3.org>
Alan, thank you

Personally, I wonder if we can say less about text wrap; how it’s best done in various languages, how to take into account forced or desorable line-breaks, hyphenation, and so on — this could be a tar-pit.


> Begin forwarded message:
> 
> From: Alan Stearns <stearns@adobe.com>
> To: David Singer <singer@apple.com>, Bert Bos <bert@w3.org>
> Cc: "w3c-css-wg@w3.org" <w3c-css-wg@w3.org>
> Subject: Re: Agenda+ review 1st WD of WebVTT
> Date: March 30, 2015 at 14:22:58 PDT
> 
> On 3/30/15, 1:37 PM, "David Singer" <singer@apple.com> wrote:
> 
>> It would be nice to get the CSS group’s feedback, or individual feedback, 
>> soon.
>> 
>> We’re working on providing style-sheets in the CSS file (probably the 
>> most-sought ‘missing feature’ from this review).
>> 
>> 
>>> On Feb 20, 2015, at 5:04 , Bert Bos <bert@w3.org> wrote:
>>> 
>>> On Thursday 19 February 2015 07:28:01 fantasai wrote:
>>>> On 02/18/2015 12:36 PM, Tab Atkins Jr. wrote:
>>>>> On Wed, Feb 18, 2015 at 9:34 AM, Sylvain Galineau 
>>>>> <galineau@adobe.com> 
>>> wrote:
>>>>>> All this feedback seems technical. Did I miss the reason it’s
>>>>>> happening on this list?
>>>>> 
>>>>> We sometimes gather feedback and then send it as a group?  I thought
>>>>> that's what was happening here.
>>>> 
>>>> We still gather it on www-style...
>>> 
>>> The list for discussions of WebVTT is <public-tt@w3.org> and that is 
>>> also 
>>> where the TTWG asks us to send our group's comments. (See the slide 
>>> called 
>>> "Reviews" in https://www.w3.org/2015/Talks/0212-WebVTT/)
>>> 
>>> Each of us can join that list and send personal comments, too, but the 
>>> TTWG 
>>> asked for our comments as a group and I agree with them it is more 
>>> efficient 
>>> that we discuss first among ourselves and then send them the outcome. 
>>> That's 
>>> why I asked to put it on the agenda.
>>> 
>>> It doesn't mean we need to have consensus on our comments.
>>> 
>>> 
>>> I think the comments so far are already very useful. I volunteer to 
>>> draft a 
>>> response to the TTWG, after we discussed them a bit more.
> 
> My comment for the collection is either on WebVTT or CSS Text level 4. The 
> definitions for line balancing should be rationalized, and probably a note 
> should be added to both that the definition may only hold for Latin text.
> 
> In WebVTT section 6.1 [1], step 11 of the algorithm for obtaining CSS 
> boxes says:
> 
> -----
> any line breaks inserted by the user agent 
> for the purposes of line wrapping must be 
> placed so as to minimize Δ across each run of 
> consecutive lines between preserved newlines 
> in the source. Δ for a set of lines is defined 
> as the sum over each line of the absolute of 
> the difference between the line's length and 
> the mean line length of the set.
> 
> -----
> 
> In Text level 4 section 5.1 [2], the definition of text-wrap:balance says:
> 
> -----
> 
> Line boxes are balanced when the standard deviation from 
> the average inline-size consumed is reduced over the block 
> 
> (including lines that end in a forced break).
> 
> -----
> 
> 
> I’d be happy to adopt WebVTT’s second sentence if that’s deemed better, 
> but I’m not that happy about the first sentence. If you assume a forced 
> break is always a paragraph boundary, then different line lengths before 
> and after the break are fine. But if you consider a forced break to not 
> break apart the paragraph, then different line lengths before and after 
> the break are bad.
> 
> Thanks,
> 
> Alan
> 
> [1] http://dev.w3.org/html5/webvtt/#processing-model
> [2] http://dev.w3.org/csswg/css-text-4/#text-wrap

David Singer
Manager, Software Standards, Apple Inc.
Received on Monday, 30 March 2015 21:36:47 UTC

This archive was generated by hypermail 2.3.1 : Thursday, 5 October 2017 18:24:21 UTC