InBroadcast - January 2023 - 42

42
www.inbroadcast.com | Vol: 13 - Issue 1 | January 2023
InMedia
Closed Captioning Update cont'd...
specific features, event scheduling
and the creation of new live closed
captioning tasks. It
supports
large
array
standard
of
inputs,
a
including
capture cards, analog
sound cards or virtual devices, as
well as streaming feeds. The output
is equally streamlined by simplifying
the overall
process with native
delivery integrations, supporting the
majority of encoders and streaming
APIs.
improvement
control, expediting
adaptability
and
idioms and other
local
to
every captioning scenario. Constantly
adapting to local
pronunciations,
speaking
characteristics, our language models
maintain high-quality standards even
in situations such as breaking news
situations that demand continuous
captioning. Our AI-driven models
are refined daily, sourced from the
network's
ongoing programming
and statistical models from the web,
instantly
adding
unusual
names
and terms relevant for the upcoming
news cycle, supported by standard
newsroom computer systems like
These on-top integrations
provide a broader degree of custom
vocabulary
VoiceInteraction's Automatic Closed Captioning with task lists for CC and translation
NPS as well as MOS for added
integration. The platform identifies
speakers and detects transitions to
increase caption readability and flow
as well as distinguishing multiple
spoken languages. This allows live
multilingual
broadcasting,with
automatic
produced
premises
translation on top of
captions, working on
without
an internet
connection. As a global company, we
provide automatic closed captions
for more than 35 languages, allowing
any TV station to comply with the
highest accessibility standards with
A Close Look at Closed-Captioning
C
With Ciro A. Noronha, Ph.D., Cobalt Digital Inc.
losed-captions have been around
for a long time now, and are a
legal requirement in many countries.
They " travel " together with the video
in some sort of ancillary channel, and
the display device overlays them in
the video under user control. This is
the main difference between Closed
and Open captions; Open captions
are " burned " into the video and
cannot be turned off.
We are going to focus on the
carriage and distribution of ClosedCaptions
(CC).
In the old Standard
Definition analog video days, CC was
carried in a line belonging to the
Vertical Blanking Interval, using the
EIA-608 standard. At 4 bytes/frame,
that gave you about 960 bits/second
to work with. And that was good for a
while until compressed digital video
came about.
The folks who invented compressed
video very helpfully
left space in
there for " user data " , where one
could stick extra non-video bits
-
such as CC, which could now be
carried in its native format as bits
and not encoded in a video line. For
a while, it was like the Wild West for
CC in digital compressed streams -
lots of proprietary solutions with no
interoperability.
It was not a difficult
problem to solve, and solutions were
needed, so people got to work ahead
of standardization.
The advent of
High Definition signals made it even
more interesting, due to the lack of
an analog baseline. We could go
over all the twists and turns of that
story, but eventually the standards
came through and sorted out all the
pain points:
* EIA-708 defined
a more
advanced captioning system with 10
times the bit rate of EIA-608, and the
ability to carry EIA-608 captions.
* SMPTE ST 334M defined a way
to carry captions in SDI baseband
digital signals, in the ancillary data
space - making it independent of
resolution.
CDI 9905-MPx
* ATSC A/53 standardized the way
the captions are carried in MPEG-2
compressed
the same for
Europe?
streams. A/72 did
H.264 and is also
applicable to H.265.
This is all US-centric. What about
Well, they had Teletext.
While that is now mostly gone, part of
it lives in OP-47, which is a subset of
Teletext for carrying captions. There
are a set of standards on how to carry
these in baseband digital video (also
in the ancillary data space) and in
compressed transport streams - but
as a separate flow, with timestamps
to align it with the video.
Nowadays, ST 2110 uncompressed
video over IP is all the rage - what
about that?
data is mapped
to
Simple: SDI ancillary
ST 2110-40
flows, and in baseband, CC is in the
ancillary data, so that problem is
solved too.
In summary: all the bits and pieces
of the CC " plumbing " are in place,
and the right products seamlessly
implement them, so you don't have
to worry about it.
https://www.cobaltdigital.com
absolute confidence. "
Wowza's
Streaming Engine
software integrates closed captioning
into streaming video, making online
content
accessible to a broader
audience. It can ingest caption data
from a variety of in-stream and filebased
sources and convert it to the
appropriate format. The company's
supporting Streaming Cloud service
offers
closed
streaming
global
cloud
video delivered via
platform.
captioning for live
a
Wowza
Streaming Engine accepts CEA-608
captions embedded in live streams,
as Action Message Format
onTextData in input
streams.
(AMF)
streams, or
embedded as AMF onCaption and
onCaptionInfo in input
Using a Java API, it can also connect
to back-end caption providers. For
outbound video, Wowza Streaming
Engine directly embeds
CEA-608
or WebVTT captions in live streams
played back via Apple HLS. For ondemand
content, Wowza Streaming
Engine
can
convert
and
deliver
captions that are embedded in the
video content as well as captions
that are delivered in external files
alongside the video content.
Wowza Streaming EngineTM
http://www.inbroadcast.com http://bit.ly/3vZD8pI https://www.cobaltdigital.com https://www.cobaltdigital.com https://www.cobaltdigital.com https://www.cobaltdigital.com https://www.cobaltdigital.com
InBroadcast - January 2023

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