[opendtv] Re: News: No Motive for HDTV Rollouts
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 28 Jun 2004 08:46:41 -0400
Kon
You are making this more complex than needed.
There are two functional blocks that are decoupled in every digital
receiver or STB.
1. Decoders - the components that turn the bits into image samples;
2. Image processing - the components that take arbitrary sample
rasters and transform them for presentation at the local screen
resolution (or as a window within the larger display raster).
The second function is well evolved and fully capable of taking ANY
raster and scaling it for presentation. It is worth noting that all
image processing systems have upper limits in terms of the
combinations of raster size and frame rates that they can support.
Currently about 63 million samples per second is common, but this is
now doubling in some implementations as 1920 x 1080 at 60P display is
becoming not only feasible, but affordable.
On the decoder side, there are tow issues.
1. Which codecs to support;
2. Is the codec implementation conformant or just a subset of the
specification?
Clearly there are only a handful of codecs that are being used in the
broadcast world. It is equally clear that any STB can implement all
of the arbitrary, programmable codecs that have emerged from the
world of IT. What is more important is whether the implementation is
conformant. Broadcasters have tied their hands in many regions of the
world by selecting subsets of formats. The cable and DBS guys have
tended to do fully conformant implementations so that they can take
full advantage of all of the handles for controlling the use of
bandwidth.
The reality is that it does not cost a penny more to provision a
fully resolution independent system (both codecs and display
processors). It is just a matter of proper implementations rather
than politically driven format limitations.
Regards
Craig
At 7:37 PM -0700 6/27/04, Kon Wilms wrote:
> >But cable and satellite do not really have these restrictions so we
>>will probably see more in between resolutions there. Personally I
>>think resolution should vary instantly and continuously based upon the
>>channel capacity and the possible benefits offered by the source.
>>Stat muxing re-encoders should be able to change them on the fly.
>>
>>
>>
>Ofcourse they do. They make their own restrictions. Restrictions mean
>simplicity and simplicity means a low-cost STB.
>
>Now if youre talking pirated movies and that whole scene of video caps
>in 640x272 and other 'inbetween' resolutions, then you may have a point.
>But you aren't going to see these used anywhere except some 'dude's HTPC
>or PC.
>
>If youre in the real world, good luck trying to convince the digital
>asset management folks that you want to support anything under the sun.
>
>Newbie datacast rollouts have previously attempted the 'use any
>resolution' mechanism. Ofcourse the first thing to do is chuckle as the
>extoll the virtues of the type of system you envisage. Eventually they
>come to their senses and realize that it is more expedient and less time
>consuming to pick a short-list of standard resolutions and one codec and
>use this across the board. Anything else wastes time and money.
>
>As for statmuxing VBR, you can do this already. You can use your
>automation system to control the encoders and flip them between SD and
>HD in the AM, or whatever the configuration is. All this stuff is
>addressable over IP these days - no rocket science there.
>
>However, changing resolutions at every flip of the coin is likely to
>cause your STBs to fall over. Implementing such a system is an excercise
>in futility.
>
>Cheers
>Kon
>
>
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