[opendtv] Re: PR: Analog Devices' JPEG2000 IC Enables Wireless High-Definition Video Distribution in the Home
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 25 Aug 2005 15:50:35 -0400
Craig Birkmaier wrote:
> But wavelets have had a difficult time historically
> competing in the Interframe compression arena,
> because of the need to introduce some kind of block
> based coding to handle the interframe predictions.
It would indeed be interesting to see comparisons of
compression efficiencies. However, I don't think a
wavelet-based MPEG algorithm would use block base
coding at all.
MPEG now uses blocks, because that's what the DCT or
integer transform produce. So if you start out with
blocks at the I frames, you use a block-based
approach for the B and P frames.
If instead your I frames are based on frequency windows,
you create the predictions or interpolations based on
frequency windows, not blocks. You simply adjust the
strategy based on the structure of the I frame.
For example, perhaps the low frequency images show less
variability than the higher frequency images, and can
more easily be predicted or interpolated, or in any
event don't need to be transmitted as often as the
higher frequency components of the frame.
So an efficient moving image algorithm which uses
the DWT as its basis can be created. One which does not
simply repeat the entire DWT every single time.
Bert
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