[opendtv] Re: Delay
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 12 Dec 2006 17:36:53 -0500
John Shutt wrote:
> Well, we run an HD and an SD. Our Program Manager wants to run 4 SDs
> during the daytime and an HD/SD combo in the evenings. In a larger
> market such as NYC, I can easily see doubling the number of program
> streams without compromising HD.
>
> However, with the current ATSC technology, our running multiple SDs
> is simply a ploy to invoke the "multicast must-carry" that was
> negotiated between NCTA, APTS, and PBS.
"doubling the number of program streams without compromising HD." I
think you are referring to use of H.264? How is it any more difficult,
technically, to add H.264 to ATSC than it was to add it to DVB-T?
If anything, the French have a much harder time of it, to offer HDTV
over DTT. Because of the legacy problem, even with H.264 codecs, they
can only get two HD streams total on the air, in the test markets. Do
you see that somehow as easier than what you have to work with today?
Here are the numbers again:
HDTV here, compatible with all receivers today, takes ~10-18 Mb/s,
depending on whether it's sports or not. And *no new codec* required.
To transmit HDTV in France requires ~6 Mb/s for the SD stream + ~6 to
~12 Mb/s for each HD stream, which is why a 22 Mb/s channel is assigned
for two HD program streams.
The total is 12 to 18 Mb/s, to transmit HD simulcast with SD, in France,
and only a small fraction can even watch the HD terrestrial.
So how exactly do they have it easier than you?
> As Craig so often points out, our DTV signal has become a
> placeholder to gain access to the cable head end.
And you see virtue in that?
Bert
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