[opendtv] Re: 7% penetration for UK HD-DTT by 2012: report

Craig Birkmaier wrote:

> But we were talking about a specific story, which I believe
> Bert posted, describing the situation in the UK; this was the
> source of the quote.
>
> You see Bert, what is relevant here is the migration path and
> business model that is being formed via the interplay of the
> UK Broadcasters and Ofcom. There will be one DVB-T2 multiplex
> for four HD channels in the multiplex. We are talking about
> an average bit rate of 8 Mbps per HD channel.
>
> This is ONLY possible thanks to the improved coding
> efficiency of h.264.

Craig, you are confusing two different posts, and a couple of different
topics mentioned in each one. And that is why you are concluding 8 Mb/s
for an HD stream, which is not anything stated in any of the posts. (And
anyway, is not completely out of the question with H.262, e.g. in 720 at
24p mode.)

I posted both stories. So here goes.

In the most recent one, with the same subject title as above, here are
the two important points made:

"'Improvements in compression technologies like MPEG-4 AVC are making
HD-DTT solutions a possibility,' says Graeme Packman, Principal
Consultant at Understanding & Solutions, 'although only with a very
limited number of channels.'"

So this first part, according to the actual HD H.264 bit rates as
reported separately by the BBC, by Ofcom, and by the DTG, is overstated.
Introduction of HDTV in Europe does not appear to depend on any
additional efficiencies provided by H.264, because the HD bit rates, as
reported by these three groups, are in the 16-18 Mb/s regions, using
H.264. (We can go back and ferret out those quotes too. Three sources is
a decent number though, isn't it?)

Then this report goes on to explain what needs to be done to create
enough spectrum for multiple HD streams, rather than just very few:

"According to the report, the UK is currently taking the lead in
addressing some of these issues and has two separate sets of proposals."

And that's where they are referring to DVB-T2 or the Ofcom MIMO scheme
(or maybe the MIMO scheme is also classified under "DVB-T2"). And BTW,
much of this fretting is caused by the fact that these new HD streams
have to be simulcast over and above the existing SD service. It would
otherwise be very simple to just replace one existing SD stream with an
HD stream, in each multiplex, and offer at least as many HD channels as
there are multiplexes.

Then comes the 4 HD streams per multiplex.

That idea came from a different article I posted, subject "Ofcom paves
the way for UK HD on DTT," dated 3 April. First, it says "up to four
high-definition channels as digital switchover is completed in the UK in
2012." That would be over a multiplex freed of SD traffic, which SD
traffic was crammed into the remaining multiplexes.

But then it also says:

"Once this [relocation of SD channels] is complete, Multiplex B will be
upgraded to use new technologies and standards."

So, Ofcom mentioning "new technologies and standards" suggests probably
the MIMO scheme, since that was THEIR proposal. In which case, four HD
streams over 44 Mb/s means 11 Mb/s avg per stream.

As I showed previously, some HD channels in the US are already down to
something close to that bit rate. And worse, using 1080i, which is
supposed to compress less efficiently than 720p.

So you see, Craig, H.264 does not appear to be carrying any huge amount
of responsibility in the European introduction of HDTV, other than the
fact that it is being mandated. But sure, H.264 at 11 Mb/s is likely to
give better results than H.262 at 11 Mb/s. H.264 is however not
absolutely essential in this.

So let's not make a bigger deal out of it than it deserves.

Bert
 
 
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