[opendtv] Re: MPs back Ofcom stance on spectrum sale
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 24 May 2007 15:55:49 -0400
Craig Birkmaier wrote:
> You are talking about the number of samples that are transferred
> to the display over some unit of time. This has NOTHING to do
> with the information content of those samples.
What I am talking about is 960 cycles/line, 1080 lines/frame, 60
frames/sec for 1080 at 60p, compared with 640 cycles/line, 720
lines/frame, 60 frames/sec for 720p, and half again as much info in each
case for the chrominance. So this is as much image info as each format
can carry, including any spurious noise or anything else, and any amount
of entropy or lack thereof.
Now that can be compressed by any algorithm you like. Just use the same
algorithm for each format, when making the comparison of channel
capacity requirement.
>> I said that when/as/if a compression algorithm comes along
>> that provides a true 2:1, or slightly better improvement,
>> compared with H.262, THEN the transmission of 1080p will be
>> feasible in the existing RF channels.
>
> This would ONLY be true if the information content and entropy
> did not increase with the higher resolution format.
I gave you the maximum theoretical. Max content, including noise, in
each format. The ratio is 2.25:1.
Now certainly, you can posit any number of situations that are less than
that max. For example, a 720p example of flat gray, compared with a very
detailed color scene in 1080p. Or a nice clean signal used for the 720p
stream, and a noisy static-filled signal for the 1080p source. But give
me a scene loaded with detail and color, then capture that in both 720p
and 1080p, with both cameras equally noise free, and the difference in
bit rate should not exceed 2.25:1.
> Sorry Bert but this is not legacy thinking The reality is
> that the vast majority of content that is being delivered
> today and will be delivered in the next decade will NOT be HDTV.
Allowing for a 1080p transmission mode in no way precludes 720, 480p,
etc. It is simply an additional mode that was not practical back in
1994, so it wasn't considered in the original HDTV transmission formats.
The "legacy thinking" part is to consider what might apply today as what
must apply in the future. You know, just like a couple or three years
ago, when it seemed to some people unlikely that LCDs would replace CRTs
in short order. They cited production costs, production volumes, and
whatever else. But LCDs took over regardless. I'm saying that 1080p
displays are becoming commonplace now, and if new codecs are added to
ATSC and DVB-T, I would not rule out that a 1080/60p transmission mode
could also be added. If the new codec is truly capable of 2:1
improvement, the 1080/60p mode *IS* feasible.
And flat panels DO make larger screen sizes practical, compared to
hulking CRTs. With larger screen sizes, people CAN appreciate the need
for good HD modes. And old movies or old TV shows archived in 35mm film
CAN be retransmitted as HDTV in the future.
Bert
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