Abstract: An apparatus and method for generating a rotating clock video wipe from two voltage ramps. The voltage ramps are rotated according to rotation data supplied by a controller. The rotated ramps are combined and fed to an output signal generator and then a video mixer.

Abstract: An apparatus and method for generating waveform signals for the production of a variety of borders for video wipes by varied processing of the output of a ramp generator.

Abstract: A digital effects unit is integrally combined with a video switcher apparatus by interrupting various selected video signal and control paths in the switcher and, in particular, the mix effects signal from the first mixer and the pattern signal from the pattern generator, and re-routing the corresponding signals to respective inputs of the digital effects unit. The resulting manipulated video and key output signals therefrom are supplied to a second, downstream mixer which combines the digital effects with conventional switcher effects.

Abstract: A digital effects loop is inserted in the video and key signal buses which extend to a mixer of a switcher apparatus, and a digital effects unit is coupled to the loop. Circuitry is included in the loop to interrupt the particular bus or buses and the signal or signals are re-routed to provide inputs to the digital effects unit. The latter supplies transformed video and/or key signals back to the continuation of the respective interrupted bus or buses, and then to the mixer to be used thereby in place of the original signals.

Abstract: A silent audio switch provides switching between multiple audio sources while eliminating the "pop" caused by switching spikes. Two internal buses are used for each visible external bus, whereby a new audio signal is first switched to an off-air bus opposite an on-air bus, any switching spike is allowed to subside, and then a fast mix is made between the two buses to derive the new audio signal as the switch output signal.

Abstract: An analog gate configuration employing multiple input transistors, eliminates distortion in its output signal when switching between multiple input signals during a corresponding switch-over interval when the input transistors are sharing current, by providing circuitry for sensing the occurrence of the switch-over interval. The sensing circuitry modulates a current source during the switch-over interval to selectively increase the current to be shared by the input transistors such that the current through each input transistor is maintained constant for any transistor which contributes to the output signal.