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Fwd: Implementing Assistive Technologies

From: Glenn Adams <glenn@skynav.com>
Date: Wed, 4 Nov 2015 08:26:57 +0800
Message-ID: <CACQ=j+eS_w7T+Lyd8FJux2KEh0S-xKDce=MueoRGZDRAoseSOQ@mail.gmail.com>
To: TTWG <public-tt@w3.org>
FYI. Nice write-up that includes some coverage on IMSC and WebVTT.

---------- Forwarded message ----------
From: SMPTE Newswatch <communications@smpte.org>
Date: Wed, Nov 4, 2015 at 1:28 AM
Subject: Implementing Assistive Technologies
To: Glenn Adams <glenn@skynav.com>

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Table of Contents
Implementing Assistive Technologies <#150ce6cc4af86968_NW1>
I <#150ce6cc4af86968_NB1>TU OK's Immersive Audio Standard
W <#150ce6cc4af86968_NB2>here are the 4K HDMI Switchers?
R <#150ce6cc4af86968_NB3>emote DVR Progress <#150ce6cc4af86968_NB3>
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The current issue of the *SMPTE Motion Imaging Journal* is now Available in
the Digital Library

Exclusive online peer-reviewed articles are available only in the Digital
November 2015 #1

*Hot Button Discussion*

* Implementing Assistive Technologies By Michael Goldman *
Since *SMPTE Newswatch* last examined the topic of closed captioning and
other accessibility technologies a couple of years ago
not much has changed in terms of governmental regulatory requirements on
broadcasters to widen access to modern communication technologies. Indeed,
the only major recent action taken by the FCC regarding accessibility
related to the expansion of rules regarding how to get critical emergency
information to consumers with visual impairments
making that information accessible on their so-called “second screen”
personal assistive devices. However, since the Twenty-First Century
Communications and Video Accessibility Act of 2010
was passed, the media industry has steadfastly been seeking ways to make
captioning, video description, and other enhancements more consistently
available with their content across all platforms. In fact, the action in
this space right now appears to be focused mainly around how to most
efficiently implement the FCC’s requirements across an industry that
“broadcasts” content just about everywhere, to everyone, using both
traditional and non-traditional methods, and delivery and viewing systems.

As discussed previously in *Newswatch*, the traditional television
broadcast industry has remained stable and efficient in terms of providing
closed captions by adhering to the established captioning standards,
CEA-608, and its digital television descendant mandated by the FCC,
CEA-708. Methodology-wise, television broadcasters continue to author
captions in the CEA-608 format, and put them through a transcoding process
to convert them into the 708 format as the final step in the broadcast
chain. This methodology is used because 708 has never been “natively”
adopted by the caption authoring industry as a wholesale replacement, since
most archival content, hardware, and software infrastructure remains based
on 608.

It is, however, “an interesting question” how changes in broadcast
television picture creation, transmission, processing, and viewing due to
the industry’s ongoing ultra-high-definition (UHD) transition could impact
captions for broadcast content, including the integration of broadband
delivery, suggests Michael Dolan, founder of the Television Broadcast
Technology Consulting Group, chairman of the ATSC Technology and Standards
Group 1
chair of SMPTE Working Group 24-TB, and a SMPTE Fellow. But Dolan suggests
that this evolution to UHD and broadband delivery provides an opportunity
to introduce new caption technology along the way.

“Caption systems today already support at least eight colors—some of them
more—and there does not seem to be any requirement from the authoring
community for a broader set of colors than what is available today, unlike
video, where you are trying to provide very smooth transitions between
shades of all the different colors, and a wider color gamut and higher bit
depth make a remarkable difference to the viewing experience,” Dolan
explains. “When it comes to captions, I’m not aware of a requirement where
you would need or want to make two subtle shades of red, for instance. That
simply wouldn’t serve the purpose of helping the hard-of-hearing person
discriminate text for different speakers or sound effects. However, it
would complicate the decoder mixing to have two color models in play, so as
you move to higher dynamic range, wider color gamut in video, ultimately
the captions have to be easily composited into the video plane. And that
process can get a little more complicated when you are working with one
color model for the video and another for the text. So one would expect
enhancements to caption technology to facilitate this [in the future], even
if more colors are not needed.”


Meanwhile, in the increasingly busy commercial content streaming space, the
industry has been turning to the SMPTE Timed Text (SMPTE-TT) format
for broadband distribution of captions. Since the FCC formally declared
SMPTE-TT as a so-called “safe harbor,” meaning commercial broadcasters who
used it would be considered compliant with the law now and for the
foreseeable future, the industry “has really taken that to heart, but they
have had to examine on a technical level what that means exactly,” Dolan

By that, Dolan means that after the FCC’s declaration that SMPTE-TT was the
way to go, the industry had to get to work trying to find ways to coalesce
around a common profile of SMPTE-TT as the standard choice for captioning
commercial streaming video content. This is an important step since, until
recently, captioning had existed across the Web pretty much in a
hodge-podge of formats and systems. In this regard, getting both commercial
and Web content to converge around a common profile remains a work in
progress, Dolan suggests.

“Some time ago, the UltraViolet industry forum created a profile of SMPTE
Timed Text, because it is a rather large set of technologies, not all of
which are needed to do a good job on captions and movie subtitles
specifically,” he says. “That profile did a good job for captions, and it
formed the basis of a new initiative by the W3C [Worldwide Web Consortium]
with the profile known as IMSC1 [Internet Media Subtitles and Captions 1.0]
That is now close to publication, and more and more folks are looking at
adopting it as the profile for the safe harbor version of SMPTE Timed Text.
Right now, there are reference implementations underway.
“There are a number of commercial media delivery silos on the Internet that
are using some profile of [SMPTE Timed Text] already, but most of them do
not disclose what they are doing exactly, so it is a little difficult to
talk about who is adopting it and who isn’t, other than to say that many
programmers who deliver content to tablets and other ‘second-screen’
devices are using a version of it when they deliver their content.”

However, Dolan quickly adds that the volume of programmers and content, and
the rapidly evolving nature of the Internet, combined with the typical
nature of what it takes to roll out a new technology or standard even under
the best of circumstances, means it will take a long time to coalesce
broadcasters around a common profile such as IMSC1 in terms of
standardizing caption formatting. For one thing, some software developers
and Web browser companies have gravitated toward another option—WebVTT
That methodology relies on a simpler markup language built on Subtitle
Resource Tracks (SRT), and has become popular for captioning some types of
Web-based videos.

And for another thing, according to Dolan, major commercial content
streaming services like Netflix, Amazon Prime, and others were well into
development of their own proprietary processes before the industry got
around to pushing toward standardizing commercial media delivery on the Web.

“They are still converting not only video and audio, but also captions to
whatever they have already designed for their silos, and much of that
pre-dates a lot of the work over the last few years with respect to
captions, certainly,” he says. “Some of them are moving in the direction
[of SMPTE Timed Text] and some aren’t—it’s really on a case-by-case basis.

“So a lot of progress has been made. But has everyone converted to a single
format or fully deployed IMSC1? No. But there has been a lot of work put
forward and a lot of activities are going on that are starting to adopt
IMSC1, both in standards’ bodies and in commercial silos. It’s a process,
but we are not even close to a common format, that’s for sure.”

Broadcast, of course, is not the only content delivery area where assistive
technology is required, nor are captions the only area where there have
been interesting developments in this category. In the world of digital
cinema, for instance, captions are a relatively stable topic. DCI
distributions now include closed-caption standards built around an
Ethernet-based synchronization protocol, associated resource presentation
list, and a content essence format that permits content creators to
distribute DCI versions of their movies with up to six languages of
interoperable closed captions associated with them. The industry also has a
standardized protocol for how digital cinema servers talk to captioning
devices, as well as well-established standards for descriptive audio in
place that are carried in DCI packages
Further, as Dolan points out, the Interoperable Mastering Format (IMF) has
“already embraced IMSC1” so new studio movies will typically be mastered to
be optimized for streaming platforms going forward.

At the same time, manufacturers have been making interesting strides
regarding how to make such assistive technologies practical in the cinema
space. When it comes to the issue of descriptive audio—that is, a separate
audio track designed to describe or narrate what is happening in the
picture to assist visually impaired viewers—hardware manufacturers have
been offering a variety of solutions in recent years. For cinema
applications, companies like Dolby, Sony, and USL, among others, are
offering a range of technologies that provide closed captions to individual
consumers on small personal devices, or audio signals through small,
wireless RF receivers attached to standard headphones worn by impaired

And for home viewers, “the methods of carrying descriptive audio have been
mature for some time,” says Sripal Mehta, principal architect, broadcast,
for Dolby Laboratories and co-designer, along with Harold Hallikainen, of
the digital cinema closed caption communication protocol standard described
above. “In some cases, a separate audio program with descriptive video
mixed in is sent as an alternate sound program to the main audio program.
The issue with this is that, in many cases, the main program audio is
stereo or 5.1, while the descriptive video track may only be mono or
stereo. Another method is to send a separate descriptive video track, which
would be mixed, at playback time, with the main video. The benefit of this
approach is that the visually impaired viewer gets the full surround
experience, as opposed to a compromised stereo or mono experience. The
Dolby encoding/decoding system takes care of ‘ducking,’ or reducing the
volume of the main audio track when the descriptive video track dialogue is
Mehta adds that descriptive audio has become “a standard part of [Dolby’s]
offerings, and is being adopted by our consumer electronics partners, as
well as broadcasters,” and he suggests this trend is proliferating across
the industry. And that’s not the only evolution in the assistive technology
space in the broadcast world. He adds that another paradigm shift includes
the shifting of descriptive audio tracks into the element-based, or
object-based audio delivery world.

“With object-based audio, music and effects, dialogue, and descriptive
video are sent as separate elements, and are mixed together at playback
time,” Mehta says. “This method delivers a premium experience to each
listener of every need, provides the ability to adjust dialogue level for
increased intelligibility, and reduces the overall bit rate for different

And related to the notion of “increased intelligibility” is the growing
push toward what Mehta calls “dialogue enhancement” as another application
to assist hearing-impaired consumers.

“That’s the ability to pick out dialogue from the ambience of the content,”
he says. “Next generation audio codecs, including Dolby AC-4
support dialogue enhancement, which involves advanced signal processing to
improve the audibility and intelligibility of dialogue for both pre-mixed
stereo and 5.1 audio programs, as well as object-based audio. Dialogue
enhancement is a valuable feature for those who are hard-of-hearing.”

*News Briefs ITU OK's Immersive Audio Standard*
As reported recently by *TV Technology*
the ITU recently announced approval of Recommendation ITU-R BS.2088-0,
which essentially is an open audio standard designed to make feasible
immersive broadcast sound experiences in combination with
ultra-high-definition TV (UHDTV) pictures. The recommendation, which you
can read here
is based on existing Resource Interchange File Format (RIFF) and WAVE audio
formats, and codifies standards that will allow single files to carry
entire audio programs and metadata for all combinations of channel-based,
object-based, and scene-based audio available for those programs. When
implemented for users who have the right technology in their homes, the
idea is to permit them “to adjust the level of immersive audio” on UHD
programs, according to the article.
*Where are the 4K HDMI Switchers?*
A recent column by Rodolfo La Maestra on the HDTV Magazine site
takes a look at one of the understated problems with ongoing transition to
4K broadcasting: a lack of all the associated components that consumers
with sophisticated home theaters might need to make efficient 4K viewing
worth the trouble to begin with. In particular, with the arrival of 4K
video players, UHD Blu-ray players on the horizon, and more, he suggests
that manufacturers have not kept pace in terms of providing a basic element
that home theaters with multiple components will need in 4K scenarios—4K
HDMI switchers. “The market offered 4K TVs for the past three years and 4K
players for at least a year, but the industry did not react quickly enough
regarding 4K HDMI switchers that can comply with their requirements,” La
Maestra writes. He suggests the industry needs to find a solution
considering that most current 4K consumer displays only have one input
capable of 4K HDMI 2.0 that are HDCP 2.2 compliant, while “there will soon
be more 4K sources to connect to the display, so the need for capable AVRs
and HDMI switchers to consolidate those connections will soon grow.” In his
article, La Maesta also published reaction to this concern from several
switcher manufacturers whom he spoke to earlier this year at the Infocomm
2015 tradeshow.

*Remote DVR Progress*
Recent cable industry news headlines included a report that progress is
apparently being made on making the concept of the remote or cloud DVR a
reality. Industry site Fierce Cable recently covered news
that Charter Communications was making plans with technology partner Cisco
to conduct a remote DVR trial for IP video to the home, as well as
conducting experiments to enable remote content distribution through IP in
the home. These plans were disclosed in a recent filing Cisco made with the
FCC, according to the report, which added Charter and Cisco were shortly
about to begin field trials. The idea of remote DVR technology is to permit
users to record TV shows and store the recordings in a cloud-based server,
rather than on an at-home, set-top box. Conceptually, this would reduce the
cost or need for certain types of set-top boxes, and allow users to access
recordings from different devices and locations. The report adds that
Comcast and Cablevision are also working on similar technologies.

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Received on Wednesday, 4 November 2015 00:27:48 UTC

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