
SMPTE RP 168,
Definition of
Vertical Interval Switching Point for
Synchronous Video Switching.
When sync is represented in analog or digitized 4fs c
form, a raised-cosine transition having a risetime (from
10% to 90%) of 140+20 ns is imposed; the midpoint of
the transition is coincident with the idealized sync.
Switching between video sources is performed in the
vertical interval, to avoid disruption of sync or picture.
Switching occurs 30+5 IJS after O H of the first normal
line of each field. In 480i systems, switching occurs
midway through line 10. (If field 2 were dominant,
switching ...