Digital Video Decoder Architecture

• US 20090180027A1
• Filed: 01/12/2009
• Published: 07/16/2009
• Est. Priority Date: 01/12/2008
• Status: Active Grant

• Current Assignee: Zhangjiagang Kangde Xin Optronics Material Co., Ltd. (Kangde Xin Composite Material Group Co., Ltd.)
• Original Assignee: Huaya Microelectronics, Inc.
• Inventors: Xiao, Peng, Wong, Hsiu Min, Jang, Sheng De
• Granted Patent: US 8,174,621 B2
• Time in Patent Office: Days
• US Class Current: 348/639
• CPC Class Codes: H04N 9/646 for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
• CPC Class Codes: H04N 9/66 for synchronous demodulators
• CPC Class Codes: H04N 9/72 for reinsertion of DC and slowly varying components of colour signals camera processing pipelines for reinsertion of DC or slowly varying components of colour signals H04N23/87
• CPC Class Codes: H04N 9/78 for separating the brightness signal or the chrominance signal from the colour television signal, e.g. using comb filter

Abstract

A digital video decoder architecture is provided wherein chrominance values are determined first, then luminance values are determined, in part, based on the previously determined chrominance values. In this architecture, luminance separation occurs after and based on

Claims

1. A digital video decoder comprising:

a chrominance demodulator comprising

an input port coupled to receive a composite video baseband signal (CVBS) signal;

a first output port to provide a first color signal (U′

); and

a second output port to provide a second color signal (V′

); and

a first filter (comb filter 600) comprising

a first input port coupled to the first output port of the chrominance demodulator (UV color decoder) to accept the first color signal (U′

);

a second input port coupled to the second output port of the chrominance demodulator (UV color decoder) to accept the second color signal (V′

);

a third input port coupled to receive the CVBS signal; and

an output port to provide a first luminance signal (Y_COMB) based on the first color signal (U′

), the second color signal (V′

) and the CVBS signal.

2. The digital video decoder of claim 1, wherein the CVBS signal is a corrected CVBS signal based on an asynchronously sampled digital CVBS signal.

3. The digital video decoder of claim 1, further comprising a correction circuit comprising:

an input port to accept a digital CVBS signal, wherein the digital CVBS signal comprises an asynchronously sampled signal; and

an output port to produce the CVBS signal having samples synchronized to the CVBS signal.

4. The digital video decoder of claim 1, wherein the first filter comprises a comb filter.

5. The digital video decoder of claim 1, wherein the filter comprises a multi-directional comb filter.

6. The digital video decoder of claim 1, further comprising a notch filter comprising:

an input to receive the CVBS signal; and

an output to provide a notched luminance signal (Y_NOTCH) derived from the CVBS signal.

7. The digital video decoder of claim 1, further comprising:

a mixer (700) comprising

a first plurality of input ports coupled to receive a plurality of different first color signals (U′

, U_2D, U_3D);

a second plurality of input ports coupled to receive a plurality of different second color signals (V′

, V_2D, V_3D);

a third plurality of input ports coupled to receive a plurality of different luminance signals (Y) comprising a first filtered luminance (Y_COMB) and a notch filtered luminance signal (Y_NOTCH);

mixing logic coupled to the first, second and third pluralities of input ports to combine the plurality of different first color signals (U), the plurality of different second color signals (V), and the plurality of different luminance signals (Y);

a first output port to provide a first mixed color signal (U_MIX);

a second output port to provide a second mixed color signal (V_MIX); and

a third output port to provide a mixed luminance signal (Y_MIX).

8. A method of decoding a digital video signal, the method comprising:

receiving a composite video baseband signal (CVBS) signal;

demodulating a chroma signal from the CVBS signal to provide a first color signal (U′

) and to provide a second color signal (V′

); and

filtering the CVBS signal, based on the first color signal (U′

), the second color signal (V′

), and to provide a first luminance signal (Y_COMB).

9. The method of claim 8, further comprising correcting an asynchronously sampled digital CVBS signal to produce the CVBS signal.

10. The method of claim 8, further comprising:

converting an analog CVBS signal by asynchronously sampling the analog CVBS signal to produce a digital CVBS signal; and

correcting the digital CVBS signal to produce the CVBS signal having samples synchronized to the CVBS signal.

11. The method of claim 8, wherein filtering the CVBS signal comprises filtering using a multi-directional comb filter.

12. The method of claim 8, wherein filtering the CVBS signal comprises filtering using a comb filter.

13. The method of claim 8, further comprising notch filtering the CVBS signal provide a notched luminance signal (Y_NOTCH) derived from the CVBS signal.

14. The method of claim 13, further comprising mixing the notched luminance signal (Y_NOTCH) and the first luminance signal (Y_COMB) to produce a mixed luminance signal (Y_MIX).

15. The method of claim 14, wherein the act of mixing comprises:

scaling the notched luminance signal (k₁*Y_NOTCH) and the first luminance signal ((1−

k₂)*Y_COMB); and

summing the signals to produce a mixed luminance signal (Y_MIX=k_Y1*Y_NOTCH+(1−

k_Y1)*Y_COMB).

16. The method of claim 8, further comprising mixing a plurality of different first color signals (U′

, U_2D, U_3D) to produce a first mixed color signal (U_MIX), wherein;

a first signal of the plurality of different first color signals comprises the first color signal (U′

);

a second signal of the plurality of different first color signals comprises a first output signal from the filter (U_2D); and

a third signal of the plurality of different first color signals comprises a second output signal from the filter (U_3D).

17. The method of claim 16, wherein the act of mixing comprises:

scaling each of the plurality of different first color signals (U′

*(1−

k₁−

k₂), k₂*U_2D, k₂*U_3D); and

summing the scaled plurality of different first color signals to produce the first mixed color signal (U_MIX=U′

*(1−

k₁−

k₂)+k₂*U_2D+k₂*U_3D).

18. The method of claim 16, further comprising mixing a plurality of different second color signals (V′

, V_2D, V_3D) to produce a second mixed color signal (V_MIX), wherein;

a first signal of the plurality of different second color signals comprises the first color signal (V′

);

a second signal of the plurality of different second color signals comprises a first output signal from the filter (V_2D); and

a third signal of the plurality of different second color signals comprises a second output signal from the filter (V_3D).

19. The method of claim 18, wherein the act of mixing comprises:

scaling each of the plurality of different second color signals (V′

*(1−

k₁−

k₂), k₂*V_2D, k₂*V_3D); and

summing the scaled plurality of different first color signals to produce the first mixed color signal (V_MIX=V′

*(1−

k₁−

k₂)+k₂*V_2D+k₂*V_3D).

20. A digital video decoder comprising:

means for receiving a composite video baseband signal (CVBS) signal;

means for demodulating a chroma signal from the CVBS signal to provide a first color signal (U′

) and to provide a second color signal (V′

); and

means for filtering the CVBS signal, based on the first color signal (U′

), the second color signal (V′

), and to provide a first luminance signal (Y_COMB).