Mode decision using approximate 1/2 pel interpolation

1. A method for encoding a video signal, comprising the steps of:

(A) generating first sub-pel data used in at least one of (i) a motion estimation and (ii) a mode decision by first filtering reference data;

(B) generating second sub-pel data used in a motion compensation by second filtering said reference data, wherein

(i) a first performance of said first filtering is different than a second performance of said second filtering,

(ii) said first filtering is not used in said motion compensation,

(iii) said second filtering is not used in said at least one of said motion estimation and said mode decision,

(iv) said second filtering utilizes at least six of a plurality of non-zero taps and

(v) said first filtering utilizes less than six of said non-zero taps; and

(C) compressing said video signal in response to said motion estimation, said mode decision and said motion compensation.

2. The method according to claim 1 , wherein said second performance matches a third performance of a third filter used in said motion compensation in a video decoder to minimize drift.

3. The method according to claim 1 , wherein step (A) comprises the sub-steps of:

generating said first sub-pel data used in said motion estimation using said first filtering; and

generating third sub-pel data used in said mode decision using a third filtering of said reference data, wherein a third performance of said third filtering is different than both said first performance and said second performance.

4. The method according to claim 3 , wherein said first filtering, said second filtering and said third filtering are performed in parallel.

5. The method according to claim 1 , wherein said first filtering and said second filtering are performed in parallel.

6. The method according to claim 1 , wherein a first sub-pel resolution of said first filtering used in said motion estimation matches a second sub-pel resolution of said second filtering for said motion compensation.

7. The method according to claim 1 , wherein said first sub-pel data is used in both (i) said motion estimation and (ii) said mode decision.

8. The method according to claim 1 , further comprising the step of:

starting an integer pel search before generating said first sub-pel data for said motion estimation.

9. The method according to claim 1 , wherein a resolution of said first filtering used in said motion estimation comprises a half-pel resolution.

10. The method according to claim 1 , further comprising the step of:

generating an encoded bitstream compliant with at least one of an International Organization for Standardization/International Electrotechnical Commission 14496-10 standard and an International Telecommunication Union-Telecommunications Standardization Sector Recommendation H.264.

11. An encoder circuit comprising: at least one processor configured to

(i) generate first sub-pel data used in at least one of (a) a motion estimation and (b) a mode decision by first filtering reference data,

(ii) generate second sub-pel data used in a motion compensation by second filtering said reference data and

(iii) compress a video signal in response to said motion estimation, said mode decision and said motion compensation,

wherein

(i) a first performance of said first filtering is different than a second performance of said second filtering,

(ii) said first filtering is not used in said motion compensation,

(iii) said second filtering is not used in said at least one of said motion estimation and said mode decision,

(iv) said second filtering utilizes at least six of a plurality of non-zero taps and

(v) said first filtering utilizes less than six of said non-zero taps.

12. The encoder circuit according to claim 11 , wherein said second performance matches a third performance of a third filter used in said motion compensation in a video decoder to minimize drift.

13. The encoder circuit according to claim 11 , wherein said motion estimation uses said first sub-pel data and said mode decision uses a third sub-pel data generated by third filtering said reference data, wherein a third performance of said third filtering is different than both said first performance and said second performance.

14. The encoder circuit according to claim 13 , wherein said first filtering, said second filtering and said third filtering are performed in parallel.

15. The encoder circuit according to claim 11 , wherein said first filtering consists of two of a plurality of non-zero taps.

16. The encoder circuit according to claim 11 , wherein said first filtering consists of four of a plurality of non-zero taps.

17. The encoder circuit according to claim 11 , wherein said first sub-pel data used in said mode decision comprises half-pel data.

18. A circuit for video encoding comprising:

means for generating first sub-pel data used in at least one of (i) a motion estimation and (ii) a mode decision by first filtering reference data; means for generating second sub-pel data used in a motion compensation by second filtering said reference data, wherein (i) a first performance of said first filtering is different than a second performance of said second filtering, (ii) said first filtering is not used in said motion compensation, (iii) said second filtering is not used in said at least one of said motion estimation and said mode decision, (iv) said second filtering utilizes at least six of a plurality of non-zero taps and (v) said first filtering utilizes less than six of said non-zero taps; and

means for compressing a video signal in response to said motion estimation, said mode decision and said motion compensation.