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Hard Mattes in Telecine Xfer



--- Forwarded mail from "Randy Blim" <rblim at laserpacific.com>

                       Subject:                               Time:7:34 AM
  OFFICE MEMO          Hard Mattes in Telecine Xfers          Date:6/25/96

Is there a "standard" in telecine tranfsers of letter-boxed material for the
precise placement of the hard matte?  Is there an accepted placement in terms
of video lines for the start and stop of actual picture information for such
formats at 1.66, 1.78, 1.85, 2.35 etc.?

Looking at transfers from various telecine houses it appears that 1.85 hard
mattes can be placed in a variety of places, thus centering the image up or
down a few lines.   With the advent of current waveform monitors, it would
seem easy to conform to a standard.  Is there one?

DVD and other MPEG1/2 standards are capable of playing bitstreams containing
just the active picture area and relying on the 'player' to center the picture
and display the hard matte, and current analog letter-boxed laserdiscs have
the hard matte inserted during the telecine transfer.
One can calculate the placement mathematically, based on centering the image
in the tv raster, but in actual practice it varies quite a bit (10-15 lines)
in placement.   Is there a reason for the variance?

Randy Blim
Laser Pacific Media

--- End of forwarded message from "Randy Blim" <rblim at laserpacific.com>