[opendtv] Re: Qualcomm on Channel 55
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 22 Jun 2005 19:00:30 -0400
John Golitsis wrote:
> I've actually been somewhat afraid to mention this,
> oddly fearing that it will come to pass, but the
> logical thing to do in ATSC is to use MPEG2 SD for
> one channel, and an AVC sub-channel for HD. That
> way, no receivers stop working. You'd have
> something like 15-16Mbps for the AVC channel, which
> is plenty.
We have discussed this several times over the years.
The question is, why bother?
If you are like France or the UK, starting out with
MPEG-2 SD only, then planning to upgrade to HD, of
course this is a good way to introduce HD without
disenfranchising all existing customers. But in the
US and in Australia, HD is already available. So you
would be preventing HD reception to folks who have
HD now.
What's more, in the US, you don't gain much or
anything with this simulcast. The total bit rate of
the MPEG-2 SD + AVC HD streams is basically identical
to a single MPEG-2 HD stream that all can view. So
why bother?
Australia is saddled with the worst of both worlds,
in a sense, because they did not mandate receivers
capable of HD modes for everyone. As a result, they
get hit with a big penalty when doing simulcasts of
SD and HD today.
I think the way to introduce AVC here is for schemes
like USDTV, or any other CA system, to adopt AVC.
Also, include AVC, starting as soon as economically
possible, in new receivers, so as to eventually phase
out MPEG-2 compression altogether.
Bert
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