Grass Valley PROFILE FAMILY v.2.5 - Manual (Page 56)

Chapter 2 Using the Profile Configuration Manager
56 Profile Family
Figure 15. Analog Composite Video Input dialog box, Advanced Control tab (B)
2. Click a setting for decode mode. Decode mode determines how the
chrominance and luminance information is separated for conversion for
storage. There are three options for the current analog composite cards and
four options for the earlier cards:
- ² Notch Filter . Decode mode separates the chrominance by using a notch
filter around the chrominance subcarrier. This leaves the high frequency
luminance intertwined with the chrominance. A notch decoder readily
determines horizontal lines are line-to-line luminance. Fine vertical lines
can be more difficult.
- ² Comb Filter . Decode mode tries to separate high frequency luminance
from the chrominance using the same notch filter as the notch decoder, but
also takes information from the next line. It uses this information to
determine if high frequency is luminance or chrominance. A comb
decoder readily determines finely spaced vertical lines are luminance. A
lack of line-to-line phase alteration causes difficulty with fine horizontal
lines.