[opendtv] Re: Carriage of various extra types of data in digital TV
- From: "Russ Wood" <russ.wood@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 2 May 2008 15:25:06 +0100
Tom, what geographical limits do you want to apply to the answer - this
is a view from Europe.
For example in the UK there are subtitles/captions (can be
multi-language, bitmap not character coded), audio description, DSM-CC
carousel carrying an MHEG-5 application and its data replacing the
teletext service.
In the rest of Europe the bitmapped subtitles are often replaced by a
teletext stream (coded as bytes of data replicating the whole teletext
VBI), if there is a digital application it will most often be a DSM-CC
carousel of MHP application and data.
Open-TV based systems have a different application environment.
There are often streams carrying private data for an EPG - for where the
EIT tables aren't good enough.
Most transport streams are multi-channel, carrying 4 or more SD videos
plus the above, themed channels may share capacity and switch over at a
particular time of day. An inactive channel may carry an application as
a place-holder.
Support for audio description was sparse until about a few months ago
when Sony and Panasonic both launched new ranges of ITDVs which had AD
built in.
Most STB and IDTV support the MHEG-5 application environment.
Where the STB is not bound by the broadcaster to a particular EPG the
receiver will have at least a rudimentary EIT based EPG but which may
not have the luxury of lots of cache.
Regards - Russ Wood
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of Tom Barry
Sent: 02 May 2008 12:43
To: opendtv
Subject: [opendtv] Carriage of various extra types of data in digital TV
Digital TV was spec'd out with the ability to have multiple sub-channels
plus various extra non-AV types of data in each stream. Is there any
consensus about what types will usually be carried on cable or
satellite?
I'm guessing that multi-must-carry will not come about and that any type
of PSIP or caption data probably WILL be carried, no matter what's in
it. Anyone disagree? What about other types of data that can be
embedded in the primary program stream? Anybody know the current FCC
stance? Or even current common practice?
This could pretty much set the standard of what actually gets used since
broadcasters these days seem to mostly care about cable carriage and may
not invest practically anything for antenna-only material.
Also, anybody know what current integrated digital TV's usually support?
- Tom
--
Tom Barry trbarry@xxxxxxxxxxx
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