[opendtv] Re: [oldvtrs] So Much for HDTV]
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 22 Aug 2008 18:11:06 -0400
Dan Grimes wrote:
> Macroblocking is one artifact. But I would also consider
> the extreme soft areas as an artifact as well. Such as when
> there is no detail in water splash (such as water polo,
> butterfly, etc.). In fact, the softening can be so bad that
> objects completely disappear.
>
> And there may be little to no macroblocking at times in the
> high motion areas, but it is also extremely blurry, such as
> twisting dives and sprinter's legs. This is probably just
> blur from slow shutter speeds and not actually a
> compression artifact
Right, exactly. Complaining about an artifact that has nothing to do
with MPEG compression is a different matter. What's the "shutter speed"
of a digital HD camera? If it's something on the order of 1/60th of a
second (or so), it's not going to freeze action very well. Which by the
way helps the MPEG process, because all edges are nicely blurred
already, as if prefiltered.
With a still camera, 1/60th of a second shutter speed is typically only
used for stationary subjects. It's usually considered to be the slowest
shutter speed adequate for hand-held photography, not to freeze rapid
motion. To freeze a runner going across the frame, I'd certainly be
looking at 1/400th at least, with a still camera.
Bert
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