[opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
- From: "Adam Goldberg" <adam_g@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 7 Aug 2008 12:04:01 -0400
CRC is a one-way hash, not compression. Or, if you like, it's 100% lossy
compression...
On Thu, Aug 7, 2008 at 11:56 AM, John Willkie <johnwillkie@xxxxxxxxxxxxx>wrote:
> Yeah, I can't wait to see that feature deployed in the wild, aside from
> Thales PSIP/PSI generators region 1 rating region table, I've yet to see
> that. (Of course, there was that bug that existed for about 6 years in one
> of the stated decode tables …)
>
>
>
> I was thinking about how a CRC-32 can be considered as a compressed value,
> too…
>
>
>
> That said, I should point out that one might be able to get 2:1 or 3:1
> compression with Huffman encoding in PSIP text strings, but nothing like
> 50:1.
>
>
>
> John Willkie
>
>
> ------------------------------
>
> *De:* opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] *En
> nombre de *Adam Goldberg
> *Enviado el:* Thursday, August 07, 2008 8:44 AM
>
> *Para:* opendtv@xxxxxxxxxxxxx
> *Asunto:* [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
>
>
>
> To be super ultra hyper technical, there is some (optional) compression of
> text strings in PSIP.
>
> On Thu, Aug 7, 2008 at 11:41 AM, John Willkie <johnwillkie@xxxxxxxxxxxxx>
> wrote:
>
> Well, to be hyper-technical, there is no compression of PSIP or PSI. They
> are not sending uncompressed essence ...
>
> John Willkie
>
> -----Mensaje original-----
> De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
> nombre de maitken@xxxxxxxxxx
> Enviado el: Thursday, August 07, 2008 3:37 AM
> Para: opendtv@xxxxxxxxxxxxx
> Asunto: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
>
> Not sure what your definition of 'full-bandwidth' is, but I can assure all
> that they are not sending 'uncompressed' anything...
>
> Mark
> Sent from my Verizon Wireless BlackBerry
>
> -----Original Message-----
> From: "Don Moore" <don@xxxxxxxxxxxxxx>
>
> Date: Thu, 7 Aug 2008 02:40:56
> To: <opendtv@xxxxxxxxxxxxx>
> Subject: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
>
>
> WRAL has the advantage of Full-Bandwidth to Cable and (I assume)
> Satellite. The Raleigh Market has high cable/satellite penetration,
> meaning that WRAL can sacrifice their OTA Bandwidth to mobile
> customers since a large percentage of their viewers are cable and
> satellite. The net result is different streams to different
> receivers.
>
> They have the luxury of being able to feed cable homes one
> uncompressed signal with its various sub-channels, while OTA viewers
> watch the compressed ATSC signal.
>
> I'm not saying it's bad, it's just circumventing what the intention of
> HDTV was supposed to be and doing something that most broadcasters can
> not duplicate because of either their relationship with their local
> cable systems or lack of advanced research in the technology. Not
> everybody can pull this off.
>
> Are we creating One Program Service for Cable/Satellite/Internet and a
> second for OTA?
>
>
>
> On Wed, Aug 6, 2008 at 11:41 PM, Tom Barry <trbarry@xxxxxxxxxxx> wrote:
> > Supposedly from Broadcast Engineering though I copied it from AVS
> > <http://www.avsforum.com/avs-vb/showthread.php?t=1056025>. I'm not sure
> I
> > understand it correctly but it looks like they got a total of 900 kbps
> (2
> > channels, 300+600) after error correction overhead from using a total of
> 4.5
> > mbps of the channel bandwidth.
> >
> > - Tom
> >
> > ---------------------------------------------------
> > From Broadcast Engineering - WRAL tests mobile DTV
> > Broadcast Engineering Mobile TV Update
> >
> > WRAL tests mobile DTV
> >
> > Users in Raleigh-Durham reported reliable signal reception in most parts
> of
> > the station's existing coverage area.
> >
> > WRAL-DT, the CBS affiliate in Raleigh-Durham, NC, owned by Capitol
> > Broadcasting Company (CBC), conducted a series of mobile DTV tests last
> week
> > using the Mobile-Pedestrian-Handheld (MPH) system promoted by Harris
> > Broadcast and others. Hosted by CBC's New Media Group, the tests featured
> > seven handsets given to station executives living in different parts of
> the
> > state. Users reported reliable signal reception in most parts of the
> > station's existing coverage area.
> >
> > To kick off the July 21-25 trial, the station hosted a reception last
> > Tuesday in which about 50 participants were driven in a bus around the
> area
> > with prototype LG Electronics mobile handsets that featured
> MPH-compatible
> > reception chips inside. Signal reception of two channels (half rate at
> > 600kb/s and one-quarter rate at 300kb/s) using about 4.5Mb/s (including
> > turbo coding) of the station's 19.4Mb/s on-air DTV stream was reportedly
> > strong everywhere they went during the 10-minute ride — even at 70 miles
> per
> > hour.
> >
> > The goal of the service, according to John Harris, WRAL's director of
> > programming, is to extend the reach of the station's television channel,
> and
> > make it available everywhere our viewers are. The initial plan is to
> > simulcast the on-air DTV signal. WRAL-TV broadcasts CBS network and its
> own
> > local programming in the 1080i HDTV format as well as in SD digital.
> >
> > "We're excited about the possibilities," John Harris, WRAL's director of
> > programming, told Broadcast Engineering. "The priority is to offer WRAL's
> TV
> > signal in another way, in another place. I took one [handset] east of the
> > station and I just kept driving until the signal dropped out. I got
> pretty
> > far before that happened, so I can see the potential of this service."
> >
> > LG Electronics, Zenith Electronics and Harris, all proponents of the MPH
> > scheme, helped out with the field trials. WRAL-DT uses a Harris Sigma CVD
> > UHF transmitter, with an MPH module, for the weeklong test.
> >
> > In a statement, James F. Goodmon, CEO of CBC, said "mobile DTV
> broadcasting
> > enables WRAL to better serve our viewers, communities, and advertisers by
> > providing a strong combination of anywhere access, two-way communication,
> > and mobility."
> >
> > In 1996, Harris worked with WRAL-DT as one of the first DTV stations in
> the
> > country. Two years later, when John Glenn made his historic return to
> space,
> > Harris worked with WRAL to conduct the first live HDTV broadcast of a
> space
> > shuttle launch to audiences nationwide. Now, the station is the first to
> > promote mobile DTV service in the state of North Carolina. WRAL predicts
> > that more than 200 million portable devices will be sold in 2008,
> although
> > few if any will have the necessary MPH reception chips inside.
> >
> > WRAL-TV and Capitol Broadcasting Company are part of the Open Mobile
> Video
> > Coalition (www.openmobilevideo.com), a nationwide group of broadcasters
> > driving the deployment of mobile digital broadcast television. Commercial
> > deployments are forecast for 2009. The group hopes to have an established
> > standard available to broadcasters by the February 2009 analog shutoff
> date.
> > --
> > Tom Barry trbarry@xxxxxxxxxxx
> >
> >
> >
> >
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