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2-Line Interpolator

The 2-line interpolator actually generates a new field, when the original field is in parity

violation. Each line of this new field is calculated by a weighted average of the 2

neighboring lines. This process solves the problem of parity violation and vertical jitter, but

the drawback is a reduction of the vertical resolution on the interpolated fields, that appear

unfocused. Another side effect is the alternation of original fields (perfectly focused) and

interpolated fields (unfocused), resulting in a "pumping" video signal.

4-Line Interpolator

The 4-line interpolator uses a more sophisticated calculation based on the 4 neighboring

lines. By using suitable coefficients for the weight of each line in the resulting calculation,

we apply this interpolation to all fields. The final result is a permanently, slightly unfocused

picture. The advantage is a stable output signal with no jitter and no "pumping", but the

vertical bandwidth is even more reduced.

The interpolator is of course always disabled at 100% playback speed, because there is

no parity violation.

EVS uses the same techniques with the Super Slow Motion disk recorder, working with all

models of Super Motion cameras (150/180 Hz). The only difference between the

processing of Super Motion and normal scan (50/60 Hz) signals is that the interpolator is

always disabled at 33% playback speed, because the Super Motion signal does not cause

parity violation at this particular speed.

Whatever the choice, the resulting picture is thus always a compromise between stability

and resolution. With EVS systems, the operator always has the choice between any of

the 3 above described techniques: no interpolation, 2-line interpolation or 4-line

interpolation. Even if the operator chooses to use the interpolation, this process will be

automatically disabled when not necessary (100% playback for 50/60 Hz signal, 33% and

100% playback for 150/180 Hz signal).

Note

All professional VTRs use line interpolation in PlayVar mode to avoid vertical

jitters.

Default value is interpolator off for all configurations except SuperLSM

configuration in which 4-line interpolator mode is enabled.

14 4. Software Specifications

EVS Broadcast Equipment S.A. - January 2013 Issue 11.01.C

EVS XTnano User Manual

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