[opendtv] Re: Kennard and Powell to the rescue
- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sun, 11 Jan 2009 17:10:59 -0800
Still more funnies.
How many dozen people in the u.s. have HD radio? 100?
And, just what is the business/consumer model for buying a totally new home
tv set to watch 416x240 video representations of 720 or 1080 video that is
otherwise available? It might work for Cliff, but I suspect he would have
serious concerns, because it ain't analog.
You're a laugh a minute, Bert. Technology uber alles.
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Manfredi, Albert E
Enviado el: Sunday, January 11, 2009 5:03 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Kennard and Powell to the rescue
Bob Miller wrote:
> So if all you take away from the main program is 1 Mb/s how
> much of that is overhead and how much is for WHAT type of
> video, MPEG2 or MPEG4? How many bits for this MPEG2 or MPEG4
> low quality program? If its MPEG4 you will need a new receiver
> right?
The answer to the first question is in Table 6.1 of A/153. If you take
away 0.917 Mb/s of the main channel, you can provide a 1/2 rate (over
2/3 rate) robust stream of 312 Kb/s capacity. So that gives you the
extra convolutional code and the extra training sequences. Take away 1.8
Mb/s capacity, and you have 629 Kb/s of robust capacity, at 1/2 rate.
And so on.
This (or these) robust stream(s) would all be H.264 compression.
You would need a new receiver no matter what, if you wanted to be
capable of receiving the M/H streams. So sure, you would need a new
receiver. Initially, an added STB could take care of this, more or less
manually. But eventually, CE manufacturers could also build this in more
intelligently.
Users of HD radio, for example, know that when the signal of the main
digital subchannel falls below a certain threshold, HD radios seamlessly
switch back to the analog FM signal. Only for the main digital
subchannel, though. The other subchannels are allowed to go silent for a
bit of time, and they the radio reverts to the analog signal.
This same behavior could be programmed into sets with built-in M/H
capability without any huge problems. If there's only one robust M/H
stream offered, then only the main subchannel will failover to the M/H
stream. If more M/H subchannels are offered, other streams would also be
allowed to fail over.
Bert
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