- From: Philip Jägenstedt <philipj@opera.com>
- Date: Mon, 9 Sep 2013 11:27:17 +0200
- To: Glenn Adams <glenn@skynav.com>
- Cc: Silvia Pfeiffer <silviapfeiffer1@gmail.com>, Cyril Concolato <cyril.concolato@telecom-paristech.fr>, public-html <public-html@w3.org>
On Sun, Sep 8, 2013 at 6:02 AM, Glenn Adams <glenn@skynav.com> wrote: > > On Sat, Sep 7, 2013 at 5:27 PM, Silvia Pfeiffer <silviapfeiffer1@gmail.com> > wrote: >> >> I don't follow. Can you give an example of a serialized TTML document >> entity ? I thought it was XML and not binary? > (1) it can be encoded in either UTF-8, UTF-16, or any other encoding, and > contains its encoding declaration, so this effectively requires binary > (octet stream) transparency; After parsing TTML, all attributes text nodes in the DOM would already be decoded to the internal Unicode encoding (probably UTF-16) so exposing any of the text from TTML would not require a binary representation. > (2) but more problematic, it contains, even if decoded into characters, > contains LF and CR, which aren't permitted in WebVTT metadata text; WebVTT files can contain CRLF line endings and so can script-created VTTCues. What does happen is that the WebVTT parser normalizes line endings. If one wanted to cram TTML into VTTCue (see below) one could do something similar. >> > 2. Because TTML is not related to VTT, and pretending that TTML is >> > WebVTT >> > metadata text just confuses authors and implementers. >> >> Agreed - some renaming would be necessary. VTTCue could be called TextCue. > > > NO. Because VTTCue is not representative of all cue types and simply > renaming it serves no purpose. It is still VTT based. Yeah, exposing TTML using VTTCue doesn't make sense unless the TTML rendering algorithm is a strict subset of WebVTT, and I'm pretty sure it isn't. Of course, a browser which doesn't care about rendering TTML properly could transform it to some subset of VTTCue, but the whole reason that VTTCue was split from TextTrackCue was to allow for other rendering algorithms than WebVTT's. This is going a little bit from the original problem, which is what to do with in-band metadata tracks of potentially unknown kind and whether or not any browser actually wants to expose subtitles/captions to scripts without rendering them. Philip
Received on Monday, 9 September 2013 09:27:46 UTC