On Fri, 06 Apr 2001 02:14:29 GMT, Howard Ring wrote:

>Let me add a little more:
>
>If the 5:1 was lossless, then why would they use 3.3:1 in DV50? I would
>guess it isn't lossless, and thus a little bit of quality is lost each
>cycle. So when does the COmpression/DECompression take place? Obviously
>it gets compressed when originally stored to tape. When you DL it to
>disk in order to edit it, I would hope it only gets decompressed for
>viewing, and all your cuts and assemblies can be done without modifying
>the original data more than intended (i.e. data is decompressed so you
>can view where you're at, but cuts and assemblies are done using the
>still compressed data). Hopefully when you write back out to tape, you
>can just write the compressed data, and thus no CODEC cycle has taken
>place on the data now being written. When your editing involves more than
>just rearranging the data, i.e. something must be rendered, then a CODEC
>cycle must take place. I'm just trying to reason this process out here,
>does anybody know if I have it correct?

Yes, but depending on the quality of the DV-codec, you may,
or may not, need to worry about the number of rendering
generations while editing. See these for multi-generation
examples (though it has been pointed out that some of the
codecs used in the second URL have been improved):
http://www.David-Ruether-Photography.com/original_vs_10th-gen.htm
and:
http://members.home.net/dgcom/MiniDV/DVcompressors.htm
Not all DV-codecs are created equal...