Adaptive Y/C separator

1. An apparatus comprising:

a plurality of filters to separate luminance and chrominance data in a video signal; and

a selection circuit coupled with any of the plurality of filters to select a subset of the plurality of filters responsive to the video signal;

where the plurality of filters includes at least one narrow band comb filter and at least one wide band comb filter; and

where the selection circuit generates a comb selection error signal indicating how well at least one of the narrow band comb filter and the wide band comb filter fits the data.

2. The apparatus of claim 1

where the plurality of the filters includes at least one comb filter and at least one band pass filter; and

where the selection circuit indicates how well the at least one comb filter and the at least one band pass filter separates the luminance and chrominance data.

3. The apparatus of claim 2 where the selection circuit implements a blending operation.

4. The apparatus of claim 2 where the selection circuit implements a threshold decision algorithm.

5. The apparatus of claim 2 where the apparatus comprises a 3 line adaptive filter.

6. The apparatus of claim 1

where the plurality of filters includes an adaptive bandwidth comb filter.

7. An apparatus comprising:

a plurality of filters to separate luminance and chrominance data in a video signal; and

a selection circuit coupled with any of the plurality of filters to select a subset of the plurality of filters responsive to the video signal;

where the plurality of the filters includes at least one comb filter and at least one band pass filter;

where the selection circuit indicates how well the at least one comb filter and the at least one band pass filter separates the luminance and chrominance data; and

where the selection circuit selects one of a single line band pass filter, two 2 line comb filters, a 3 line comb filter, and a combination thereof.

8. An apparatus comprising:

a plurality of filters to separate luminance and chrominance data in a video signal; and

a selection circuit coupled with any of the plurality of filters to select a subset of the plurality of filters responsive to the video signal;

where the selection circuit implements a PAL modifier operation, the PAL modifier operation comprising a first order derivative function to implement a 90 degree phase shift in the chrominance channel based on whether a current pixel will generate a U or a V chrominance pixel after demodulation.

9. A method comprising:

receiving an output from a plurality of filters;

determining a subset of the filters responsive to the output;

using the subset as an adaptive filter to separate chroma and luma from a video signal;

providing at least one comb filter as one of the plurality of filters;

providing a band pass filter as at least another of the plurality of filters;

generating a first value to indicate how the band pass or comb filters fit luminance and chrominance data; and

using the first value to implement a threshold decision algorithm.

10. A method comprising:

receiving an output from a plurality of filters;

determining a subset of the filters responsive to the output;

using the subset as an adaptive filter to separate chroma and luma from a video signal;

providing at least one comb filter as one of the plurality of filters;

providing a top two line filter as at least another of the plurality of filters; and

providing a bottom two line filter as at least another of the plurality of filters.

11. A method comprising:

receiving an output from a plurality of filters;

determining a subset of the filters responsive to the output;

using the subset as an adaptive filter to separate chroma and luma from a video signal;

providing at least one comb filter as one of the plurality of filters;

providing a narrow band comb filter as at least another of the plurality of filters; and

providing a wide band comb filter as at least another of the plurality of filters.

12. The method of claim 11 further comprising using a second value to indicate how well the narrow or wide band comb filters fit luminance and chrominance data.

13. The method of claim 12 further comprising using the second value to implement a threshold decision algorithm.

14. A method comprising:

receiving an output from a plurality of filters;

determining a subset of the filters responsive to the output;

using the subset as an adaptive filter to separate chroma and luma from a video signal; and

providing at least one comb filter as one of the plurality of filters;

where determining the subset of the filters includes comparing a best fit between a 3 line comb filter and two 2 line comb filters.

15. The method of claim 14 comprising generating an indication of the subset of filters.

16. A method comprising:

receiving an output from a plurality of filters;

determining a subset of the filters responsive to the output;

using the subset as an adaptive filter to separate chroma and luma from a video signal;

providing at least one comb filter as one of the plurality of filters; and

implementing a 90 degree phase shift in chrominance data responsive to determining whether a current pixel will generate a U or a V chrominance pixel after demodulation.

17. An apparatus, comprising:

a band pass filter to filter a first delayed signal;

a top line filter to filter the first delayed signal and the second delayed signal;

a bottom line filter to filter a composite signal and the second delayed signal;

a narrow band comb filter to filter the composite, first, and second delayed signals;

a wide band comb filter to filter the composite, first, and second delayed signals;

a selection circuit to select at least one of the band pass, top line, bottom line, narrow band, and wide band filters responsive to at least one error signal.

18. The apparatus of claim 17 where the selection circuit comprises:

a band pass filter leakage circuit to filter a signal output from the band pass filter;

a narrow band comb filter leakage circuit to filter a signal output from the narrow band filter; and

a wide band comb filter leakage circuit to filter a signal output from the wide band filter.

19. The apparatus of claim 17 where the selection circuit comprises:

a band pass match filter to filter a signal output from the band pass filter, top line filter, and bottom line filter; and

a comb match filter to filter a signal output from the narrow band filter, top line filter, and bottom line filter.

20. The apparatus of claim 17 where the selection circuit generates a band pass error signal and a comb selection error signal.

21. The apparatus of claim 17 comprising a diagonal edge detector to detect a diagonal edge between the composite and second delayed signals.