[opendtv] Re: Food for thought
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 21 Feb 2007 11:51:24 -0500
Craig Birkmaier wrote:
[From the BBC HDTV report:]
"Each HD channel is likely to need bandwidth equivalent to that required
by three or four standard definition channels even when using more
advanced MPEG-4 technology."
> Figures.
>
> Here you go again drawing unfounded conclusions from the thin
> air.
Craig, being obnoxious does not make you, or anyone else, right. And
throwing a lot of words at something so basically simple does not
either.
If a 576i SD program takes, on average, roughly 5 Mb/s, that's average
and not peak, then 3 of these take an average (not peak) 15 Mb/s, and
four take an average (not peak) 20 Mb/s.
Reduce the quality of the 576i SD to an average (not peak) of 4 Mb/s,
which is what decent SD programs here use for 480i, and you're still
requiring an average (not peak) of 12 to 16 Mb/s for 3 or 4 SD programs.
The BBC claimed, from their real-world testing, that this many SD
programs would have to be removed to make room for one H.264 HDTV
program. That looks to me very much like a low estimate of 12 Mb/s, and
a high estimate of 20 Mb/s. Throw whatever prefiltering words you like
at this, the results are not a dramatic improvement compared with H.262.
As I already said, I do not doubt that H.264 will give better results as
the bit rate is reduced.
But there's no reason for over-hyping it, either. I'm not a salesman for
H.264. I'm just after some unvarnished truth, rather than press
releases.
Bert
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