[opendtv] Re: Video compression artifacts and MPEG noise reduction

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 19 Jun 2008 15:31:53 -0400

Craig Birkmaier wrote:


Summary: This paper presents an overview of the transform and
quantization designs in H.264. Unlike the popular 8/spl times/8 discrete
cosine transform used in previous standards, the 4/spl times/4
transforms in H.264 can be computed exactly in integer arithmetic, thus
avoiding inverse transform mismatch problems. The new transforms can
also be computed without multiplications, just additions and shifts, in
16-bit arithmetic, thus minimizing computational complexity, especially
for low-end processors. By using short tables, the new quantization
formulas use multiplications but avoid divisions

> So h.264 provides a significant improvement in arithmetic accuracy
> and the visibility of artifacts is reduced by acting upon smaller
> 4 x 4 regions of the image.

Actually, you will not see that "accuracy" is improved mentioned
anywhere, but rather that computational complexity is reduced. An
integer transorm is not inherently more "accurate" at all, even if the
inverse doesn't introduce any additional error. And yes, the variable
block sizes will make blocking artifacts less obvious.

> So my educated guess is that products like the Algolith device
> will not find their way into TV receivers. The shift to improved
> compression techniques will make this unnecessary.

I don't buy your reasoning, Craig, because a shift to improved
compression techniques is not something a CE manufacturer can introduce
into his product all by himself. It requires a standards change and a
migration of the broadcast system.

This box, very simply, can be used to extend the life of MPEG-2, both at
the transmission end and at the receive end. Whether it is hugely
successful or not is another matter. It took a whole lot of time to get
that point across.

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