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From: Phil@fillin.co.uk
In article ,
Roger Multi segmented wrote:
> > On Tue, 8 Jul 2003 11:24:48 +0100, "Martin Underwood"
> > wrote:
Ampexes used a drum with four heads rotating vertically,
> thus writing each frame in four slightly angled stripes as the tape ran
> past it: the three joins were often just visible. (Modern machines use
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> the angled drum with two heads, the same principle as domestic video
> recorders).
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Phil: NO - multi segmented tracks on ALL DIGITAL formats (and BCN
Format before them)
Phil: Each pass of the head only recorded 16 or 20 lines and the
characteristic features of 'quad banding' were velocity errors,
slant or scalloping: \ or ( or ) or / (corrected at the left edge each
line, but increasing to the right) due to head-tip penetration errors /
differences from the original recording, and last-line errors as these
couldn't be corrected because there wasn't another line to refer to (it
belonged to the next head every 16 or 20 lines) - this, seen in PAL-simple
showed as phase errors on the 16th/20th line.
Line by line correction of colour saturation etc came in with the AVR2
AMTEC then COLORTEC then VELOCITY corrector in VR2000s
The joins were visible - perhaps more so nowadays as those used to lining
them up are long gone to other employment.
There was also the Rank Cintel /IVC 9000 which was a 1.7" slant track
recording on 2" tape - used at Birmingham and other distant places 8-)
--
Phil Spiegelhalter: Phil@fillin.co.uk
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