[opendtv] Re: BBC Demonstrates HDTV Broadcasts over SD Channels
- From: "John Willkie" <JohnWillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 21 Jun 2005 11:10:36 -0700
Sorry, Alan, I was treading upon previous posts of mine, perhaps before you
got on the list or rose up from lurkerdom.
To have HDTV, DVB countries (with the exception of Australia, where the
issue was indentified and prevented) will need to have two transitions up
from analog. The first, which we're being told is well advance of the US
one, is to DTV transmission systems. The second is to HDTV. The only hope
to avoid the second is if in the meantime, there is a second DTV transition
in the regions where HDTV is common now, to 2K or whatever comes next.
What's wrong with it is that it's a kludge.
It's not the BBC that is in denial. It's the DVB common practices and the
regulators.
How reasonable a simulation of HDTV over transport streams do you think that
store and forward HDTV is ? (forgive the dangling participle.) Sounds to
me like a "resistance is futile" marketing ploy, barganing to avoid doing
what really needs to be done.
John Willkie
----- Original Message -----
From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, June 21, 2005 2:21 AM
Subject: [opendtv] Re: BBC Demonstrates HDTV Broadcasts over SD Channels
> I don't understand this first sentence; when has the BBC ever denied the
> benefits of HDTV? It was experimenting with it in 1978 (I was doing much
of
> that work). "Acting out", acting out what? Bargaining?
>
> The report, if you take the trouble to read it, describes a system whereby
> an HD version of a programme can be rolled out to a viewer over the
existing
> SD network such that it can be played out in sync from the viewers PVR
with
> the (later) SD broadcast of the SD programme. At least that's what I
> actually saw working. At no stage in that demonstration did Richard even
> hint that it's an alternative to transmitting HD properly, that will
happen
> fairly soon anyway. But this system could happen now, before bandwidth's
> released for HDTV, and on any digital distribution system worldwide. And
it
> could continue to work over existing SD networks that have sufficient
> headroom. What's wrong with all that?
>
> ----- Original Message -----
> From: "John Willkie" <JohnWillkie@xxxxxxxxxx>
> To: <opendtv@xxxxxxxxxxxxx>
> Sent: Tuesday, June 21, 2005 2:33 AM
> Subject: [opendtv] Re: BBC Demonstrates HDTV Broadcasts over SD Channels
>
>
> > the first step is denial, then comes acting out, followed by barganing
...
> >
> > Can't wait for acceptance of Live HDTV in the U.K. It might even come
> > before this is actually deployed. Anyone ever hear of news? How do you
> > transmit that in advance? Mexico will be doing live news in HDTV
shortly.
> >
> > John Willkie
> > ----- Original Message -----
> > From: "Craig Birkmaier" <craig@xxxxxxxxx>
> > To: "OpenDTV Mail List" <opendtv@xxxxxxxxxxxxx>
> > Sent: Monday, June 20, 2005 5:57 AM
> > Subject: [opendtv] BBC Demonstrates HDTV Broadcasts over SD Channels
> >
> >
> > > BBC Demonstrates HDTV Broadcasts over SD Channels
> > >
> > > June 20, 2005 12:00am
> > > Source: Communications Daily
> > >
> > > HDTV broadcasts over standard definition (SD) DTV channels are
> > > feasible as a result of a system developed by the BBC. If adopted,
> > > the system would beam HDTV content to British homes with HDTV-ready
> > > sets before the nation's 2008-2012 analog cutoff opens additional
> > > spectrum.
> > >
> > > Unveiling of the HD-over-SD system came at recent broadcast industry
> > > demonstrations at the BBC's R&D labs in Kingswood Warren, Surrey. The
> > > event takes place every 2 years; this year's was held against the
> > > backdrop of BBC plans to eliminate up to 25% of its work force.
> > >
> > > The HD broadcast system demonstrated exploits the growing capacity
> > > and shrinking cost of hard-drive PVRs. It uses Britain's existing SD
> > > terrestrial DTV channels -- basically digitized 625i PAL -- to carry
> > > HD content off- hours. During the day and night before the scheduled
> > > SD broadcast, an HDTV version of the program is broadcast to a PVR
> > > using a various frequencies as available. By the time the scheduled
> > > broadcast is transmitted in SD, the complete HD version is stored and
> > > ready to play from the PVR. The scheduled program contains a trigger
> > > signal that's recognized by the PVR, which automatically plays the HD
> > > version. So viewers with HDTV-ready sets see the program in HDTV
> > > instead of SD.
> > >
> > > The SD program streams at the usual broadcast rates, up to 4 Mbps.
> > > The HD version stored on the PVR plays at 17 Mbps for MPEG-2 or 12
> > > Mbps for MPEG-4, but can be downloaded at much slower rates and
> > > piecemeal. The PVR stitches it all together before playback. The
> > > system works only with recorded programs, not live coverage. But it
> > > provides a simple way to deliver movies or regularly scheduled TV
> > > series in HD before analog broadcasting is shut down and releases
> > > frequencies to carry digital HDTV live.
> > >
> > > In a related area, the BBC's Kingswood engineers have been carrying
> > > out viewer tests to determine the best scanning and display method
> > > for HDTV -- 720 lines progressive (720p) or 1080 lines interlaced
> > > (1080i). Each method was compared with conventional 625 line PAL
> > > pictures, which display 576 lines interlaced on CRTs or 576
> > > progressively on plasma or LCD panels.
> > >
> > > Viewers sat at the 2.7 meters distance from the screens typical in
> > > U.K. homes. They agreed that ordinary SD was good enough for screens
> > > up to 27". For larger screens, up to 50", 720p with 1,280 pixels per
> > > line was considered ideal. "It's time to ditch interlacing," said BBC
> > > engineer Richard Salmon. "CCD cameras and flat panel displays are
> > > inherently progressive. Interlacing is analogue compression. It's
> > > yesterday's technology."
> > >
> > > The demonstrations gave a useful reminder why flat panels are easier
> > > to watch. As Americans accustomed to 60 Hz NTSC are quick to notice
> > > when they visit Europe, interlaced PAL at 50 Hz on a CRT shows
> > > noticeable flicker, especially when the picture content is bright and
> > > white. Artificially increasing the display rate requires new CRTs and
> > > can introduce image artifacts. But LCD and plasma progressive panels
> > > show no flicker at 50 Hz because the LCD backlights are always on,
> > > and the plasma panel is using "sample and hold" to increase the speed
> > > at which the gas cells fire to emit UV light and excite the color
> > > phosphors.
> > >
> > > As for Britain's planned switch-over from analog to DTV, on
> > > technical grounds the BBC stands firmly behind telecom regulator
> > > Ofcom's plan to change terrestrial DTV modulation from 2K to 8K --
> > > that is, increasing the number of carriers for the signal to about
> > > 8,000 from the current 2,000. -- Stephen A. Booth, Barry Fox
> > >
> > > <<Communications Daily -- 06/20/05>>
> > >
> > >
> > > ----------------------------------------------------------------------
> > > You can UNSUBSCRIBE from the OpenDTV list in two ways:
> > >
> > > - Using the UNSUBSCRIBE command in your user configuration settings at
> > FreeLists.org
> > >
> > > - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
> > unsubscribe in the subject line.
> > >
> >
> >
> >
> > ----------------------------------------------------------------------
> > You can UNSUBSCRIBE from the OpenDTV list in two ways:
> >
> > - Using the UNSUBSCRIBE command in your user configuration settings at
> FreeLists.org
> >
> > - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
> unsubscribe in the subject line.
> >
>
>
>
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
>
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
>
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
