[opendtv] Re: Distribution and Transmission of TV is Going Backwards
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 20 Oct 2005 07:00:25 -0400
At 10:57 AM -0700 10/18/05, dan.grimes@xxxxxxxx wrote:
>Now my point is this: lets stop forcing a faulty progression and actually
>progress, rather than digress. We need to be focussing on fixing
>distribution and transmission so that this digital conversion actually
>results in better pictures for all. It is a waste of all our efforts and
>resources to transition to digital if we don't get a better benefit from
>it.
There is nothing faulty about the transmission systems for DTV
content, unless you consider their ability to correct lost packet
errors faulty [note: the ability to receive some forms of DTV
transmission may be less desirable than others, but this has noting
to do with delivered picture quality, assuming a receiver has an
adequate link budget].
Simply stated, the problem is that the available video compression
technology is being misused. For almost every distribution media the
system operators are trying to squeeze too much content into too
little bandwidth. This is even true for OTA broadcasters, as 19.3
Mbps is barely adequate for low stress HD content, and begins to show
problems with high stress HD content. If you add multicasting into
the equation, something has to give, and picture quality is the
victim.
There is one distribution medium that is working hard to make video
quality as good as is possible given the restrictions of their
"pipe." That would be DVDs where the content authors have taken the
time to optimize the encoding of the source. Anything that is
real-time tends to suffer when encoded due to lack of sufficient
headroom to handle peak bit rate requirements, and the limitations of
real-time encoders that may not be able to provide the best
predictions due to lack of time to fully run the block matching
algorithms.
All of this "may" improve as compression algorithms evolve, however,
the trend seems to be to squeeze harder rather than maintaining the
bit rate to improve image quality when new encoders are deployed.
It's all about keeping the quality JUST above the threshold where
people will complain.
Unfortunately there is no TECHNICAL fix for this problem. It is a
business problem that is related to maximizing the bottom line. I am
hopeful that someday, content producers will start holding the
distribution folks feet to the fire. The RIGHT way to solve this
problem is for the content producer to handle the video encoding, to
assure that the image quality is at the level they expect. THEN, they
must demand - via their distribution contracts - that the video files
be delivered as provided - NO RECOMPRESSION OR GROOMING TO REDUCE THE
BIT RATES.
Ultimately, I think this may turn out to be one of the big advantages
of file based downloads of TV content versus systems that stream
dozens or hundreds of channels. If the quality of downloads is
consistently higher than the streaming services, this may provide yet
another incentive for people to move to download services. This will
be especially true if we move to ala carte purchasing, where you pay
only for the programs you download - at that point people will be
turned off if the quality is not adequate for the price.
The only other alternative is to legislate picture quality, and
that's a sure bet to make things worse. The marketplace can deal with
this issue.
Regards
Craig
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