- From: <bugzilla@jessica.w3.org>
- Date: Mon, 13 Feb 2012 21:55:29 +0000
- To: public-html-bugzilla@w3.org
https://www.w3.org/Bugs/Public/show_bug.cgi?id=13357 --- Comment #13 from Bob Lund <b.lund@cablelabs.com> 2012-02-13 21:55:26 UTC --- (In reply to comment #12) > My intent here is to not add anything until there is at least one format that > supports this, since there is no point the HTML spec saying to do something > that can never happen. Premixed audio descriptions for visually impaired + main dialogue, as required by the recent FCC ruling (http://transition.fcc.gov/Daily_Releases/Daily_Business/2011/db0825/FCC-11-126A1.pdf), is specified in AC-3 audio used in MPEG-2 TS. This spec (http://www.atsc.org/cms/standards/a_52-2010.pdf) defines how the presence of this pre-mixed audio track is signaled: in the AC-3 bit stream information syntax (section 5.3.2) field bsmod = 2 signals the visually impaired audio stream (see Table 5.7 in section 5.4.2.2) and in the AC-3 descriptor field full_svc = 1 signals a full audio service (section A4.3), meaning the track includes the main dialogue audio. This standard is adhered to in North American broadcast channels. These AC-3 signals could also exist when these channels are redistributed over IP. -- Configure bugmail: https://www.w3.org/Bugs/Public/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the QA contact for the bug.
Received on Monday, 13 February 2012 21:55:32 UTC