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Re: DVD X-fers



Hi Robert,

>American Zoetrope has now received a request for a transfer
>from B/W negative.

> [...] Specifically, in the past, we've left our Quadra in color mode when
>working with B/W print or negative for aesthetic reasons.  [...] For DVD,
is
>there any reason we should put the Quadra into monochrome (so that
>we're sending only Y-channel information to the DigiBeta)?

As far as the conversion of a 601 digital video signal to MPEG2 for DVD is
concerned, it makes little difference where in a telecine chain you make the
signal monochrome.  Consequently, if you get more pleasing results by
running the telecine in color mode and making the picture monochrome
downstream, that should be the way to go.

>Also, we've worked with a particular compressionist who prefers that we
>do no noise reduction during the transfer.  [...] Has a rule of thumb been
>established for colorists regarding noise reduction when transferring
>for DVD?

Unfortunately, the amount of noise reduction to use in a telecine transfer
for DVD is dependent on the equipment in both the transfer suite and the
compression suite.  While everybody agrees that removal of noise is quite
important for good compression efficiency, noise reduction can in some cases
introduce subtle lag artifacts.  When compressed, these result in higher
peak bit rates, which are of course undesirable.  The trick is to use as
much noise reduction as needed, but not so much that the other artifacts
catch up.  Your compressionist probably prefers to determine this by trial
and error on the actual compression system.  If the noise reduction method
isn't specified, but you know the material is going to DVD, the best thing
to do is ask, but if that isn't practical for one reason or another, stick
to the minimum amounts of noise reduction and aperture correction you can
possibly get by with.

Best regards,
Christopher Bacon




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