Re: Streaming of WebVTT

On Jul 26, 2012, at 15:59 , Silvia Pfeiffer <silviapfeiffer1@gmail.com> wrote:

> On Thu, Jul 26, 2012 at 7:33 PM, Cyril Concolato
> <cyril.concolato@telecom-paristech.fr> wrote:
>>> No, not quite. Everything until the first empty line is regarded as
>>> the header.
>> 
>> I don't understand. The syntax (http://dev.w3.org/html5/webvtt/#syntax) says
>> that the "WEBVTT" string can optionally be followed by "either a U+0020
>> SPACE character or a U+0009 CHARACTER TABULATION (tab) character followed by
>> any number of characters that are not U+000A LINE FEED (LF) or U+000D
>> CARRIAGE RETURN (CR) characters.". Since it says "that are not LF or CR" you
>> can't have text on another line. The line starting with "WEBVTT" must be
>> followed by an empty line. This seems to be also the interpretation of
>> Anne's validator, which says "no blank line after the signature". But this
>> does not change the fact that the header, indeed, may carry interesting
>> things.
> 
> That's the Syntax definition. In step 11 in the parser, thought it says:
> http://dev.w3.org/html5/webvtt/#parsing
> 
> "Header: Collect a sequence of characters that are not U+000A LINE
> FEED (LF) characters. Let line be those characters, if any."
> 
> The way I read this is that while we haven't defined in the Syntax
> that there should be a header, the parser allows putting extra
> characters beyond the identifier line and skips everything until it
> finds the two line terminators it requires (i.e. the empty line).

Hm, we should disambiguate this; I think we need multi-line headers, up to the blank line.


David Singer
Multimedia and Software Standards, Apple Inc.

Received on Friday, 27 July 2012 23:54:49 UTC