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Re: Re: Digi Beta versus D1



Tom McMahon wrote:
> 
> MPEG and JPEG don't have to be lossy, although the fashion in which they are
> typically used is lossy.
> 

Tom is right that the quality of MPEG and JPEG compressed images depends
largely on how they are used, but technically speaking, they are lossy,
because they discard picture information that the human eye in normal
circumstances can't detect.  With MPEG1 the lossiness is pretty obvious. 
Anyone with a CD Rom can attest to that.  With MPEG2, the standard for DVD,
the lossiness is far less obvious.  With a high enough bit rate a movie can be
compressed and look nearly as good as the original source, and certainly much
better than VHS.

Post production is another matter.  DigiBeta is fine format, and for
television broadcast it's excellent.  But if I were transferring a film that
was to be later compressed for DVD, I would stick with a uncompressed format,
either D1 or D5.  You can always make a Digi- Beta clone later if needed. 
When encoding with MPEG2, I would want to start with the most artifact free
source I could get.

Phil Voss

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