SS0607-8
30 September 1988
Figure 3-3.
Part of color field one and detail A
3.
The importance of SC/H phase is primarily useful in the video tape
editing environment.
If during playback the video Signal coming off the
tape is not of the same color frame as the house reference, the video at the
machine's time base corrector output must be shifted horizontally.
The
shift can be in either direction and be up to 140 ns (one half subcarrier
cycle).
This may result in loss of active picture and a widening of
blanking, since the output processor blanking is referenced to the house.
Even if the off-tape video is of the correct color frame, the machine-output
video will be shifted horizontally to a smaller degree in an amount equal to
any SC/H phase difference between the off-tape and house video.
a. These horizontal shifts are troublesome in a tape editing
environment, especially when editing scenes together of similar content. At
the edit point, the background will appear to jump horizontally. This jump
is unacceptable and dictates the need for an SC/H phase facility.
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