On 18/09/17 20:31, Capitol wrote:
Â*Â*Â*Yes, it's called compression. It always distorts the original
source.

No, it doesnt always.

Fore axmple a ZIP file does not distiret anythung.

Lossless compression is possible, BUT for video, it takes a heck of a
lot of doing and results ion a hige delay ...consider for example a
systemn where you obly send CHANGES to a picture, and the actual picture
itself perhaps less than once a second.

That will give you very good quality no loss low bandwith video.

Until someone does a series of rapid cuits from scene to secne, where it
simply cant cope.

So in reality most stuff is good on stills and deteriorates on action,
simply because the amount of *new* informations goes up as scene
changing goes up.

I suspect, but do not know, that MP2 and other TV strandards are veryu
accurate for stills and lose nothing, the loss being in transient stuff.

It's the same with audio. Delta modulation reduces bandwith enormously,
but cannot cope with very rapid treble transients like the clash of cymbals.

I dont know exactly hwo mp2,3 and 4 do the compressing, but it doesnt
have to be lossy.

It tends to GET lossy when you try and push more information - real
genuine information that the receiver can't guess - down a too narrow pipe.

Bu thats how te modulatins schemas are constructed




One of the best ways to understand it is to look up the detailed
analysis of HDMI systems.Â* I'm sure there are other sources of data on
digital systems if you look closely. Having worked on digital phone
systems, I was always amazed that they worked as well as they do.


--
Canada is all right really, though not for the whole weekend.

"Saki"