| 摘要 |
A digital comb filter decodes composite video signals into luminance and chrominance component. A FFT circuit or band split filter circuit (16) produces a signature signal by which each video line can be correlated. Signature signals on various surrounding video lines that are of opposite subcarrier phase with the current line are compared to determine similarity and appropriate weighting coefficients for the surrounding lines. Multiplexer (18) combines high pass and low pass taps of a band spilt filter into single data stream. Line delays (20, 21, 23), with field delay memories (22, 24), provide the interlaced line above and below the current line for the comb filter. Motion detector gives priority to the frame comb signal when no motion is detected between the current line and the frame delayed signal in the same vertical position as the current line. Dynamic threshold modification suppress unwarranted comb filter failures in the presence of luma edges.
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