[opendtv] Re: MPs back Ofcom stance on spectrum sale
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 21 May 2007 11:56:13 -0400
At 5:14 PM -0400 5/19/07, Albert Manfredi wrote:
If transmission of 720 at 60p, 55.3 Mpels/sec, requires something
less than 20 Mb/s, then transmission of 1080 at 60p, 124.4
Mpels/sec, requires 2.25X as much channel bandwidth. Therefore, if
H.264 is capable of at least 2:1 reduction in bit rate compared with
H.262, which it is supposed to have been capable of from the
beginning (according to the press hypsters), then it seems a no
brainer that transmission of 1080 at 60p is on the horizon. In time,
H.264 or something else will no doubt reach that level of
performance.
There are several flaws in this argument, that work both for and against you.
First, you cannot equate pixel density and bandwidth requirements.
bandwidth requirements are determined primarily by information
content and entropy. The good news about higher resolution formats is
that they are more highly correlated, thus typically can be
compressed at a higher compression ratio for a given level of image
quality. The bad news is that they typically have more noise, and may
deliver more information, both of which requires more bits.
next, you are making an invalid assumption about the adequacy of 20
Mbps for 720P. This is well within the average bit rate requirement
for most content, but well below the peak bit rate requirement,
especially for high action content. As the EBU demo showed, 720P
benefits from the extra compression efficiency of H.264, providing
consistently high quality images at available bit rates. What the
demo did not show was how much better the quality is at a given bit
rate for H.264 versus MPEG-2. The EBU test results demonstrate that
we are still throwing away to much information when we try to push
1080@50/60P though a 20 Mbps channel.
Its all a question of quality. As the quality of 1080@60P acquisition
systems improves they will produce more information that will by
necessity need to be quantized away to make the format fit in a
constrained emission channel.
This is EXACTLY THE SAME ARGUMENT made by U.S. broadcasters in 1987.
Your consistent argument has been that HDTV is a "niche" service,
and that US broadcasters are only interested in retaining the "NTSC
franchise." So, I don't see that the UK situation is at all the
same. Unless I misunderstand what this "NTSC franchise" means. At
some point, this viewpoint will have to be updated even by you,
Craig.
The U.S. broadcasters are protecting "their" spectrum and
retransmission consent.
Now the U.K broadcasters are are using HDTV to try to protect their spectrum.
IF and when NTSC is turned off we can talk about updating the viewpoints.
It is also ironic that with a 20 year head start in the U.S., we have
made such little progress relative to the U.K.
DTV here started in 1998, DTV in the UK started in 1998. How is that 20 years?
U.S. broadcasters started using HDTV as an argument to hold onto
their spectrum in 1987. The U.K. broadcasters are now using the same
argument in 2007. You do the math.
Adoption of DTV in the US is now more than 51 percent, according to
Nielsen, and that ignores any DTT uptake completely. Just digital
cable and DBS. In the UK, it's somewhat more, maybe 60 percent,
counting all forms of DTV. I don't know offhand what the use of HDTV
per se is over here, but it is substantial. Mostly because the sale
of flat panel TVs is enormous, and they are all either ED or HD
sets. I'd say, there isn't a lot of difference, other than the fact
that here the overwhelming majority use umbillical media, and
availability of HDTV OTA.
Yes, the adoption of DTV in the U.S. is growing thanks especially to
DBS, and now a growing number of cable subscribers. But most of these
subscribers DO NOT pay for an HD tier. The majority of deployed HD
capable displays do not have access to HD content - just because
there is an ATSC tuner in there does not mean it is being used.
Regards
Craig
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
