Estimation of P frame average rate quantization parameter (QP) in a group of pictures (GOP)

1. A method of Rate-QP estimation for a P picture, comprising:

(a) inputting an input group of pictures (GOP) to a computer;

(b) selecting, on the computer, an input P picture within the input group of pictures; and

(c) outputting, from the computer to a computer readable medium, a bit rate corrected Rate-QP, R(QP), for the input P picture;

(d) wherein the outputting step comprises:

(i) calculating an intra luma (Y) Rate-QP estimate from an intra luma (Y) histogram;

(ii) calculating an intra chroma (C) Rate-QP estimate from an intra chroma (C) histogram;

(iii) offsetting the intra chroma (C) Rate-QP estimate to form an offset intra chroma (C) estimate;

(iv) calculating a non-intra luma (Y) Rate-QP estimate from a non-intra luma (Y) histogram;

(v) calculating a non-intra chroma (C) Rate-QP estimate from a non-intra chroma (C) histogram;

(vi) offsetting the non-intra chroma (C) Rate-QP estimate to form an offset non-intra chroma (C) estimate; and

(vii) setting a Rate-QP for the input P picture to a sum of:

(a) the intra luma (Y) Rate-QP estimate;

(b) the offset intra chroma (C) Rate-QP estimate;

(c) the non-intra luma (Y) Rate-QP estimate; and

(d) the offset non-intra chroma (C) Rate-QP estimate.

2. The method of claim 1 , wherein the outputting the bit rate corrected Rate-QP step comprises correcting the Rate-QP of the input P picture to produce the bit rate corrected Rate-QP, R(QP).

3. The method of claim 2 , wherein the correcting the bit rate corrected Rate-QP step comprises:

(a) partitioning a set of ordered pairs of (QP, Rate-QP) into a plurality of correction regions; and

(b) applying mapping functions for QP values in each of the correction regions to produce the bit rate corrected Rate-QP, R(QP).

4. The method of claim 3 , wherein the plurality of correction regions comprise:

(a) a high bit rate correction region;

(b) a medium bit rate correction region; and

(c) a low bit rate correction region.

5. The method of claim 4 , further comprising applying a linear interpolation for QP values in the high bit rate correction region.

6. The method of claim 4 , further comprising applying a medium bit rate correction for QP values in the medium bit rate correction region.

7. The method of claim 4 , further comprising applying a low bit rate correction for QP values in the low bit rate correction region.

8. The method of claim 1 , wherein the intra luma (Y) histogram, the intra chroma (C) histogram, the non-intra luma (Y) histogram, and the non-intra chroma (C) histogram are accumulated, for every macroblock in the group of pictures, in steps comprising:

(a) forming an estimate of a set of intra prediction coefficients;

(b) forming an estimate of a set of forward prediction coefficients;

(c) selecting between an intra mode and a non-intra mode that results in a lowest Sum of Absolute Transformed Differences (SATD);

(d) for each macroblock selected with intra mode, separating the set of intra prediction coefficients into an output accumulated intra luma (Y) histogram and an accumulated intra chroma (C) histogram; and

(e) for each macroblock selected with non-intra mode, separating the set of forward prediction coefficients into an output accumulated non-intra (Y) histogram and an accumulated non-intra (C) histogram.

9. The method of claim 8 , wherein the selecting the intra mode step comprises:

(a) selecting the intra mode that has a lowest Sum of Absolute Transformed Differences (SATD) among intra modes using a set of inputs [x], H pos , V pos , {right arrow over (h)}, and {right arrow over (v)};

(b) wherein [x] is a 4×4 block of pixels within the input P picture and

[

x

]

≡

[

x

0

,

0

x

0

,

1

x

0

,

2

x

0

,

3

x

1

,

0

x

1

,

1

x

1

,

2

x

1

,

3

x

2

,

0

x

2

,

1

x

2

,

2

x

2

,

3

x

3

,

0

x

3

,

1

x

3

,

2

x

3

,

3

]

;

(c) wherein H pos is a horizontal pixel position of the 4×4 block within the image;

(d) wherein V pos is a vertical pixel position of the 4×4 block within the image;

(e) wherein {right arrow over (h)} is a vector immediately left of the 4×4 block [x], defined as {right arrow over (h)}≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T relative to the indexing of the elements of [x];

(f) wherein {right arrow over (v)} is a vector immediately above the 4×4 block [x], defined as {right arrow over (v)}≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 ) T relative to the indexing of the elements of [x]; and

(g) wherein the lowest SATD intra mode is determined among a group comprising:

(i) a horizontal intra mode;

(ii) a vertical intra mode; and

(iii) a steady state (DC) intra mode.

10. The method of claim 9 , wherein the selecting the lowest SATD intra mode step comprises:

(a) calculating a horizontal predictor {right arrow over (H)}≡(H 0 ,H 1 ,H 2 ,H 3 ) T , a vertical predictor {right arrow over (V)}=(V 0 , V 1 , V 2 , V 3 ) T , and a steady state (DC) predictor D;

(b) calculating a horizontal cost precursor C hs and a vertical cost precursor C vs using the horizontal predictor {right arrow over (H)}, the vertical predictor {right arrow over (V)}, and the steady state (DC) predictor D; and

(d) calculating a horizontal intra mode cost C H , a vertical intra mode cost C V , and a steady state (DC) intra mode cost C D using the horizontal cost precursor C hs and the vertical cost precursor C vs .

11. The method of claim 10 , wherein the calculating of the horizontal predictor {right arrow over (H)}, the vertical predictor {right arrow over (V)}, and the steady state (DC) predictor D comprises:

(a) if H pos ≠0 and V pos ≠0 then:

(i) setting {right arrow over (H)}≡(H 0 ,H 0 ,H 2 ,H 3 ) T =[NDCT 4 ]{right arrow over (h)}

where {right arrow over (h)}≡(h 0 ,h 1 ,h 2 ,h 3 ) T ≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T ;

(ii) setting {right arrow over (V)}≡(V 0 ,V 1 ,V 2 ,V 3 ) T =[NDCT 4 ]{right arrow over (v)}

where {right arrow over (v)}≡(v 0 ,v 1 ,v 2 ,v 3 )≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 );

(iii) setting D=(H 0 +V 0 )/2;

(b) if H pos =0 and V pos ≠0 then:

(i) setting {right arrow over (H)}=(2 15 −1,0,0,0) T ;

(ii) setting {right arrow over (V)}≡(V 0 ,V 1 ,V 2 ,V 3 ) T =[NDCT 4 ]{right arrow over (v)}

where {right arrow over (v)}≡(v 0 ,v 1 ,v 2 ,v 3 )≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 );

(iii) setting D=V 0 ;

(c) if H pos ≠0 and V pos =0 then:

(i) setting {right arrow over (H)}≡(H 0 ,H 1 ,H 2 ,H 3 ) T =[NDCT 4 ]{right arrow over (h)}

where {right arrow over (h)}≡(h 0 ,h 1 ,h 2 ,h 3 ) T ≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T ;

(ii) setting {right arrow over (V)}=(2 15 −1,0,0,0) T ;

(iii) setting D=H 0 ; and

(d) if H pos =0 and V pos =0 then:

(i) setting {right arrow over (H)}=(2 15 −1,0,0,0) T ;

(ii) setting {right arrow over (V)}=(2 15 −1,0,0,0) T ; and

(iii) setting D=128×16.

12. The method of claim 10 , wherein the calculating of the horizontal cost precursor C hs and the vertical cost precursor C vs comprises:

(a) calculating the values X i,0 , X 0,i for iε0, 1, 2, 3 using the relationships

[

X

0

,

0

X

0

,

1

X

0

,

2

X

0

,

3

X

1

,

0

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1

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1

X

1

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2

X

1

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3

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2

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0

X

2

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1

X

2

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2

X

2

,

3

X

3

,

0

X

3

,

1

X

3

,

2

X

3

,

3

]

=

[

NCDT

4

×

4

]

⁢

(

[

x

]

)

;

(b) calculating the horizontal cost precursor

C

hs

=

∑

i

=

1

3

⁢



X

i

,

0



;

and

(c) calculating the vertical cost precursor

C

vs

=

∑

j

=

1

3

⁢



X

0

,

j



.

13. The method of claim 12 , wherein calculating the horizontal intra mode cost C H comprises calculating

C

H

=

∑

i

=

0

3

⁢



H

i

-

X

i

,

0



+

C

vs

.

14. The method of claim 12 , wherein calculating the vertical intra mode cost C V comprises calculating

C

v

=

∑

j

=

0

2

⁢



V

j

-

X

0

,

j



+

C

hs

.

15. The method of claim 12 , wherein calculating the steady state (DC) intra mode cost C D comprises calculating C D =|D−X 0,0 |+C hs +C vs .

16. The method of claim 10 , further comprising selecting the lowest SATD intra mode with a lowest associated intra mode cost among the group consisting of: the horizontal intra mode cost C H , the vertical intra mode cost C V , and the steady state (DC) intra mode cost C D .

17. A second non-transitory computer readable medium comprising a programming executable capable of performing on the computer the method of claim 1 .

18. An advanced video encoder apparatus comprising the method of claim 1 .

19. A method of Rate-QP estimation for a P picture, comprising:

(a) inputting an input group of pictures (GOP) to a computer;

(b) selecting, on the computer, an input P picture within the input group of pictures; and

(c) outputting, from the computer to a computer readable medium, a bit rate corrected Rate-QP, R(QP), for the input P picture;

(d) wherein the outputting the bit rate corrected Rate-QP step comprises correcting the Rate-QP of the input P picture to produce the bit rate corrected Rate-QP, R(QP);

(e) wherein the correcting the bit rate corrected Rate-QP step comprises:

(i) partitioning a set of ordered pairs of (QP, Rate-QP) into a plurality of correction regions; and

(ii) applying mapping functions for QP values in each of the correction regions to produce the bit rate corrected Rate-QP,R(QP); and

(f) wherein the plurality of correction regions comprise:

(i) a high bit rate correction region;

(ii) a medium bit rate correction region; and

(iii) a low bit rate correction region.

20. The method of claim 19 , further comprising applying a linear interpolation for QP values in the high bit rate correction region.

21. The method of claim 19 , further comprising applying a medium bit rate correction for QP values in the medium bit rate correction region.

22. The method of claim 19 , further comprising applying a low bit rate correction for QP values in the low bit rate correction region.

23. The method of claim 19 , wherein the outputting step comprises:

(a) calculating an intra luma (Y) Rate-QP estimate from an intra luma (Y) histogram;

(b) calculating an intra chroma (C) Rate-QP estimate from an intra chroma (C) histogram;

(c) offsetting the intra chroma (C) Rate-QP estimate to form an offset intra chroma (C) estimate;

(d) calculating a non-intra luma (Y) Rate-QP estimate from a non-intra luma (Y) histogram;

(e) calculating a non-intra chroma (C) Rate-QP estimate from a non-intra chroma (C) histogram;

(f) offsetting the non-intra chroma (C) Rate-QP estimate to form an offset non-intra chroma (C) estimate; and

(g) setting a Rate-QP for the input P picture to a sum of:

(i) the intra luma (Y) Rate-QP estimate;

(ii) the offset intra chroma (C) Rate-QP estimate;

(iii) the non-intra luma (Y) Rate-QP estimate; and

(iv) the offset non-intra chroma (C) Rate-QP estimate.

24. The method of claim 23 , wherein the intra luma (Y) histogram, the intra chroma (C) histogram, the non-intra luma (Y) histogram, and the non-intra chroma (C) histogram are accumulated, for every macroblock in the group of pictures, in steps comprising:

(a) forming an estimate of a set of intra prediction coefficients;

(b) forming an estimate of a set of forward prediction coefficients;

(c) selecting between an intra mode and a non-intra mode that results in a lowest Sum of Absolute Transformed Differences (SATD);

(d) for each macroblock selected with intra mode, separating the set of intra prediction coefficients into an output accumulated intra luma (Y) histogram and an accumulated intra chroma (C) histogram; and

(e) for each macroblock selected with non-intra mode, separating the set of forward prediction coefficients into an output accumulated non-intra (Y) histogram and an accumulated non-intra (C) histogram.

25. The method of claim 24 , wherein the selecting the intra mode step comprises:

(a) selecting the intra mode that has a lowest Sum of Absolute Transformed Differences (SATD) among intra modes using a set of inputs [x], H pos , V pos , {right arrow over (h)}, and {right arrow over (v)};

(b) wherein [x] is a 4×4 block of pixels within the input P picture and

[

x

]

≡

[

x

0

,

0

x

0

,

1

x

0

,

2

x

0

,

3

x

1

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0

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1

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1

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1

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2

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1

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3

x

2

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0

x

2

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1

x

2

,

2

x

2

,

3

x

3

,

0

x

3

,

1

x

3

,

2

x

3

,

3

]

;

(c) wherein H pos is a horizontal pixel position of the 4×4 block within the image;

(d) wherein V pos is a vertical pixel position of the 4×4 block within the image;

(e) wherein h is a vector immediately left of the 4×4 block [x], defined as {right arrow over (h)}≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T relative to the indexing of the elements of [x];

(f) wherein {right arrow over (v)} is a vector immediately above the 4×4 block [x], defined as {right arrow over (v)}≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 ) T relative to the indexing of the elements of [x]; and

(g) wherein the lowest SATD intra mode is determined among a group comprising:

(i) a horizontal intra mode;

(ii) a vertical intra mode; and

(iii) a steady state (DC) intra mode.

26. The method of claim 25 , wherein the selecting the lowest SATD intra mode step comprises:

(a) calculating a horizontal predictor {right arrow over (H)}≡(H 0 ,H 1 ,H 2 ,H 3 ) T , a vertical predictor {right arrow over (V)}≡(V 0 ,V 1 ,V 2 ,V 3 ) T , and a steady state (DC) predictor D;

(b) calculating a horizontal cost precursor C hs and a vertical cost precursor C vs using the horizontal predictor {right arrow over (H)}, the vertical predictor {right arrow over (V)}, and the steady state (DC) predictor D; and

(d) calculating a horizontal intra mode cost C H , a vertical intra mode cost C V , and a steady state (DC) intra mode cost C D using the horizontal cost precursor C hs and the vertical cost precursor C vs .

27. The method of claim 26 , wherein the calculating of the horizontal predictor {right arrow over (H)}, the vertical predictor {right arrow over (V)}, and the steady state (DC) predictor D comprises:

(a) if H pos ≠0 and V pos ≠0 then:

(i) setting {right arrow over (H)}≡(H 0 ,H 0 ,H 2 ,H 3 ) T =[NDCT 4 ]{right arrow over (h)}

where {right arrow over (h)}≡(h 0 ,h 1 ,h 2 ,h 3 ) T ≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T ;

(ii) setting {right arrow over (V)}≡(V 0 ,V 1 ,V 2 ,V 3 ) T =[NDCT 4 ]{right arrow over (v)}

where {right arrow over (v)}≡(v 0 ,v 1 ,v 2 ,v 3 )≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 );

(iii) setting D=(H 0 +V 0 )/2;

(b) if H pos =0 and V pos ≠0 then:

(i) setting {right arrow over (H)}=(2 15 −1,0,0,0) T ;

(ii) setting {right arrow over (V)}≡(V 0 ,V 1 ,V 2 ,V 3 ) T =[NDCT 4 ]{right arrow over (v)}

where {right arrow over (v)}≡(v 0 ,v 1 ,v 2 ,v 3 )≡(x −1,0 ,x −1,1 ,x −1,2 ,x −1,3 );

(iii) setting D=V 0 ;

(c) if H pos ≠0 and V pos =0 then:

(i) setting {right arrow over (H)}≡(H 0 ,H 1 ,H 2 ,H 3 ) T =[NDCT 4 ]{right arrow over (h)}

where {right arrow over (h)}≡(h 0 ,h 1 ,h 2 ,h 3 ) T ≡(x 0,−1 ,x 1,−1 ,x 2,−1 ,x 3,−1 ) T ;

(ii) setting {right arrow over (V)}=(2 15 −1,0,0,0) T ;

(iii) setting D=H 0 ; and

(d) if H pos =0 and V pos =0 then:

(i) setting {right arrow over (H)}=(2 15 −1,0,0,0) T ;

(ii) setting {right arrow over (V)}=(2 15 −1,0,0,0) T ; and

(iii) setting D=128×16.

28. The method of claim 26 , wherein the calculating of the horizontal cost precursor C hs and the vertical cost precursor C vs comprises:

(a) calculating the values X i,0 ,X 0,i for iε0, 1, 2, 3 using the relationships

[

X

0

,

0

X

0

,

1

X

0

,

2

X

0

,

3

X

1

,

0

X

1

,

1

X

1

,

2

X

1

,

3

X

2

,

0

X

2

,

1

X

2

,

2

X

2

,

3

X

3

,

0

X

3

,

1

X

3

,

2

X

3

,

3

]

=

[

NDCT

4

×

4

]

⁢

(

[

x

]

)

;

(b) calculating the horizontal cost precursor

C

hs

=

∑

i

=

1

3

⁢



X

i

,

0



;

and

(c) calculating the vertical cost precursor

C

vs

=

∑

j

=

1

3

⁢



X

0

,

j



.

29. The method of claim 28 , wherein calculating the horizontal intra mode cost C H comprises calculating

C

H

=

∑

i

=

0

3

⁢



H

i

-

X

i

,

0



+

C

vs

.

30. The method of claim 28 , wherein calculating the vertical intra mode cost C V comprises calculating

C

v

=

∑

j

=

0

3

⁢



V

j

-

X

0

,

j



+

C

hs

.

31. The method of claim 28 , wherein calculating the steady state (DC) intra mode cost C D comprises calculating C D =|D−X 0,0 |+C hs +C vs .

32. The method of claim 26 , further comprising selecting the lowest SATD intra mode with a lowest associated intra mode cost among the group consisting of: the horizontal intra mode cost C H , the vertical intra mode cost C V , and the steady state (DC) intra mode cost C D .

33. A second non-transitory computer readable medium comprising a programming executable capable of performing on the computer the method of claim 19 .

34. An advanced video encoder apparatus comprising the method of claim 19 .