Video encoder and portable radio terminal device

• US 20060215763A1
• Filed: 03/25/2005
• Published: 09/28/2006
• Est. Priority Date: 03/23/2005
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kikuchi, Yoshihiro, Morimoto, Michiyo
• Granted Patent: US 7,688,893 B2
• Time in Patent Office: Days
• US Class Current: 375/240.180
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/119 Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• CPC Class Codes: H04N 19/122 Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A prediction mode determining unit of a video encoder comprises a primary evaluative value calculating unit which calculates each primary evaluative value of a plurality of primary evaluative values corresponding respectively to a plurality of 4×4 intra-prediction modes with different prediction directions, for each of a plurality of 4.times. 4-pixel blocks, using the motion picture signal as a reference image signal, a secondary evaluative value calculating unit which calculates each of a plurality of secondary evaluative values corresponding respectively to the 4×4 intra-prediction modes, by applying to the primary evaluative value, weight summing which uses an evaluation coefficient corresponding to a position of each of the 4.times. 4-pixel blocks, determining unit which determines a coding prediction mode for each macro-block, using the secondary evaluative values, and coding units which coding the motion picture signal in accordance with the coding prediction mode.

Claims

1. A video encoder which codes a motion picture signal, the video encoder comprising:

means for calculating each primary evaluative value of a plurality of primary evaluative values corresponding respectively to a plurality of 4.times. 4-pixel intra-prediction modes with different prediction directions, for each of a plurality of 4.times. 4-pixel blocks, using the motion picture signal as a reference image signal.

means for calculating each of a plurality of secondary evaluative values corresponding respectively to the 4×

4 intra-prediction modes, by applying to the primary evaluative value, weight summing which uses an evaluation coefficient corresponding to a position of each of the 4.times. 4-pixel blocks;

means for determining a coding prediction mode for each macro-block, using the secondary evaluative values; and

means for coding the motion picture signal in accordance with the coding prediction mode.

2. The video encoder according to claim 1, wherein the means for calculating the primary evaluative value calculates the primary evaluative value using the following equation:

J=SAD+λ

*R

where J is the primary evaluative value, SAD represents the sum of absolute differences resulting from the 4×

4 intra-prediction mode, λ

represents a constant, and R represents the amount of codes representing the coding prediction mode.

3. The video encoder according to claim 1, wherein the means for calculating the primary evaluative value calculates the primary evaluative value using the following equation:

J=SATD+λ

*R

where J is the primary evaluative value, SATD represents the sum of absolute transformed differences obtained by subjecting the predictive residuals resulting from the 4×

4 intra-prediction mode to an Hadamard transformation, λ

represents a constant, and R represents the amount of codes representing the coding prediction mode.

4. The video encoder according to claim 1, wherein the means for calculating the secondary evaluative value calculates the secondary evaluative value using the following equation:

$E=\underset{i=0}{\overset{15}{\sum <br><br>}}<br><br>\left(\mathrm{Ji}\times <br><br>\mathrm{wi}\right)$

where E represents the secondary evaluative value, i represents the number of the 4×

4 pixel block, Ji represents the primary evaluative value, and wi represents the evaluation coefficient.

5. The video encoder according to claim 1, wherein for the plurality of 4×

4 pixel blocks, a smaller evaluation coefficient is specified for a block closer to the lower right one.

6. The video encoder according to claim 1, wherein the means for determining the coding prediction mode includes means for determining a 4×

4 intra-prediction mode candidate in accordance with the primary evaluative value, first mode selecting means for selecting either a 16×

16 intra-prediction mode candidate or a 4×

4 intra-prediction mode candidate, using the secondary evaluative value, and second mode selecting means for selecting either the intra-prediction mode or the inter-prediction mode, and the coding prediction mode is determined in accordance with a result of the selection by the first selecting means and a result of the selection by the second selecting means.

7. The video encoder according to claim 6, wherein the means for determining the coding prediction mode further includes prediction mode limiting means for limiting the number of 4×

4 intra-prediction modes to at least one if the first mode selecting means has selected the 4×

4 intra-prediction mode and if the second selecting means has selected the intra-prediction mode, using the 4×

4 intra-prediction mode candidate and means for calculating a tertiary evaluative value for each of the at least two modes, in accordance with the at least two modes, if the prediction mode limiting means has limited the number of intra-prediction modes to at least two, using a local decoding image signal as a reference image, and one of the 4×

4 intra-prediction modes is determined to be the coding prediction mode in accordance with the tertiary evaluative value.

8. A portable radio terminal device comprising the video encoder according to claim 1 and a coded bit stream obtained by using the video encoder to code the motion picture signal.

9. A video encoder which codes a motion picture signal, the video encoder comprising:

converting means for subjecting a predictive residual signal to a simplified orthogonal transformation to generate a converted image signal;

means for calculating each primary evaluative value of a plurality of primary evaluative values corresponding respectively to a plurality of 4.times. 4-pixel intra-prediction modes with different prediction directions, for each of a plurality of 4.times. 4-pixel blocks, using an added image signal obtained by adding the converted image signal to a predicted image signal as a reference image signal.

means for calculating each of a plurality of secondary evaluative values corresponding respectively to the 4×

4 intra-prediction modes, by applying to the primary evaluative value, weight summing which uses an evaluation coefficient corresponding to a position of each of the 4.times. 4-pixel blocks;

means for determining a coding prediction mode for each macro-block, using the secondary evaluative values; and

means for coding the motion picture signal in accordance with the coding prediction mode.

10. The video encoder according to claim 9, wherein the means for calculating the primary evaluative value calculates the primary evaluative value using the following equation:

J=SAD+λ

*R

where J is the primary evaluative value, SAD represents the sum of absolute differences resulting from the 4×

4 intra-prediction mode, λ

represents a constant, and R represents the amount of codes representing the coding prediction mode.

11. The video encoder according to claim 9, wherein the means for calculating the primary evaluative value calculates the primary evaluative value using the following equation:

J=SATD+λ

*R

where J is the primary evaluative value, SATD represents the sum of absolute transformed differences obtained by subjecting the predictive residuals resulting from the 4×

4 intra-prediction mode to an Hadamard transformation, λ

represents a constant, and R represents the amount of codes representing the coding prediction mode.

12. The video encoder according to claim 9, wherein the means for calculating the secondary evaluative value calculates the secondary evaluative value using the following equation:

$E=\underset{i=0}{\overset{15}{\sum <br><br>}}<br><br>\left(\mathrm{Ji}\times <br><br>\mathrm{wi}\right)$

where E represents the secondary evaluative value, i represents the number of the 4×

4 pixel block, Ji represents the primary evaluative value, and wi represents the evaluation coefficient.

13. The video encoder according to claim 9, wherein for the plurality of 4×

4 pixel blocks, a smaller evaluation coefficient is specified for a block closer to the lower right one.

14. The video encoder according to claim 9, wherein the means for determining the coding prediction mode includes means for determining a 4×

4 intra-prediction mode candidate in accordance with the primary evaluative value, first mode selecting means for selecting either a 16×

16 intra-prediction mode candidate or a 4×

4 intra-prediction mode candidate, using the secondary evaluative value, and second mode selecting means for selecting either the intra-prediction mode or the inter-prediction mode, and the coding prediction mode is determined in accordance with a result of the selection by the first selecting means and a result of the selection by the second selecting means.

15. The video encoder according to claim 14, wherein the means for determining the coding prediction mode further includes prediction mode limiting means for limiting the number of 4×

4 intra-prediction modes to at least one if the first mode selecting means has selected the 4×

4 intra-prediction mode and if the second selecting means has selected the intra-prediction mode, using the 4×

4 intra-prediction mode candidate and means for calculating a tertiary evaluative value for each of the at least two modes, in accordance with the at least two modes, if the prediction mode limiting means has limited the number of intra-prediction modes to at least two, using a local decoding image signal as a reference image, and one of the 4×

4 intra-prediction modes is determined to be the coding prediction mode in accordance with the tertiary evaluative value.

16. A portable radio terminal device comprising the video encoder according to any of claims 9 and a coded bit stream obtained by using the video encoder to code the motion picture signal.