Low cost rate-distortion computations for video compression

1. A method of distortion computations for video compression, comprising the steps of:

(A) generating a plurality of transform coefficients from a residual block of said video using a circuit;

(B) generating a plurality of quantized coefficients by quantizing said transform coefficients;

(C) generating a plurality of intermediate coefficients by calculating absolute values of said transform coefficients;

(D) generating a plurality of measures of roundoff error in said quantizing by calculating a plurality of differences between said intermediate coefficients and scaled versions of said quantized coefficients; and

(E) generating a block distortion value based on said measures of said roundoff error.

2. The method according to claim 1 , wherein said block distortion value is generated independently of a plurality of inverse Quantized coefficients produced from said quantized coefficients.

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

multiplying said measures by a plurality of weight values prior to said generation of said block distortion value.

4. The method according to claim 3 , further comprising the step of:

generating a weighted sum of squares by adding said measures, wherein said block distortion value comprises said weighted sum of squares.

5. The method according to claim 1 , further comprising the steps of:

generating a rate value based on a number of non-zero quantized coefficients produced from said residual block; and

generating a rate-distortion value from said rate value and said block distortion value.

6. The method according to claim 5 , wherein said generating of said rate value comprises the sub-steps of:

counting said number of non-zero quantized coefficients; and

generating said rate value by performing a lookup translation on said number.

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

generating said scaled versions of said coefficients by scaling said quantized coefficients.

8. The method according to claim 7 , further comprising the step of:

calculating a value based on a size of said residual block, wherein (i) said quantization is based on said value and (ii) said scaling is based on said value.

9. An apparatus comprising:

a first circuit configured to generate a plurality of transform coefficients from a residual block of video; and

a second circuit configured to (i) generate a plurality of quantized coefficients by quantizing said transform coefficients, (ii) generate a plurality of intermediate coefficients by calculating absolute values of said transform coefficients, (iii) generate a plurality of measures of roundoff error in said quantizing by calculating a plurality of differences between said intermediate coefficients and scaled versions of said quantized coefficients and (iv) generate a block distortion value based on said measures of said roundoff error.

10. The apparatus according to claim 9 , wherein said block distortion value is generated independently of a plurality of inverse quantized coefficients produced from said quantized coefficients.

11. The apparatus according to claim 9 , wherein said second circuit is further configured to multiply said measures by a plurality of weight values prior to said generation of said block distortion value.

12. The apparatus according to claim 11 , wherein (i) said second circuit is further configured to generate a weighted sum of squares by adding said measures and (ii) said block distortion value comprises said weighted sum of squares.

13. The apparatus according to claim 9 , wherein said second circuit is further configured to (i) generate a rate value based on a number of non-zero quantized coefficients produced from said residual block and (ii) generate a rate-distortion value based on said rate value and said block distortion value.

14. The apparatus according to claim 13 , wherein said second circuit is further configured to (i) count said number of non-zero quantized coefficients and (ii) generate said rate value by performing a lookup translation on said number.

15. The apparatus according to claim 9 , wherein said second circuit is further configured to generate scaled versions of said coefficients by scaling said quantized coefficients.

16. The apparatus according to claim 15 , wherein (i) said second circuit is further configured to calculate a value based on a size of said residual block, (ii) said quantization is based on said value and (iii) said scaling is based on said value.

17. An apparatus comprising:

means for generating a plurality of transform coefficients from a residual block of video;

means for generating a plurality of quantized coefficients by quantizing said transform coefficients;

means for generating a plurality of intermediate coefficients by calculating absolute values of said transform coefficients;

means for generating a plurality of measures of roundoff error in said quantizing by calculating a plurality of differences between said intermediate coefficients and scaled versions of said quantized coefficients; and

means for generating a block distortion value based on said measures of said roundoff error.