Method and apparatus for encoding/decoding multi-layer video using weighted prediction

1. A method for encoding video by performing weighted prediction on a current picture in a high layer using information concerning a picture in a low layer, the method comprising:

reading information concerning the picture in the low layer, including a weighting value used for predicting the picture in the low layer;

calculating at least one weighting factor for the current picture using the weighting value information for the picture in the low layer;

calculating a weighted sum of reference pictures to the current picture using the weighting factor, the reference pictures being in the high layer, and generating a predicted picture for the current picture using the weighted sum of the reference pictures in the high layer; and

encoding a difference between the current picture and the predicted picture,

wherein the reference pictures are different than the picture in the low layer,

wherein the picture in the low layer is the picture having a closest temporal position to the current picture in the high layer, and

wherein the picture in the low layer is not a picture having a same temporal position as the current picture in the high layer.

2. The method of claim 1 , wherein the information concerning the picture the low layer contains a base picture corresponding to the current picture and reference pictures for the base picture.

3. The method of claim 2 , wherein the reference pictures for the base picture are pictures motion-compensated by motion vectors from the base picture.

4. The method of claim 2 , wherein the reading of the information, the calculating of the weighting factor, the calculating of the weighted sum of reference pictures, and the encoding of the difference are performed if the current picture has a same reference scheme and reference distance as the base picture.

5. The method of claim 2 , wherein the calculating of the weighting factor comprises:

calculating a weighted sum of reference pictures for the base picture using predetermined coefficients; and

calculating values of the coefficients minimizing the square of a difference between the base picture and the weighted sum.

6. The method of claim 4 , wherein the coefficients include forward and backward coefficients.

7. The method of claim 6 , wherein a sum of the forward and backward coefficients is 1.

8. The method of claim 1 , wherein the calculating of the weighting factor and the calculating of the weighted sum of reference pictures are performed in units of one of a picture, a slice, a macroblock, and a motion block.

9. The method of claim 1 , wherein the calculating of the weighted sum of reference pictures comprises:

if only one reference picture exists for the current picture, calculating a product of the weighting factor and the reference picture for the current picture; and

if a plurality of reference pictures exist for the current picture, multiplying appropriate weighting factors by the plurality of reference pictures, respectively, and adding the products together.

10. A method for decoding video contained in an input bitstream by performing weighted prediction on a current picture in a high layer using information about a picture in a low layer, the method comprising:

extracting texture data and motion data from the input bitstream;

reconstructing information about the picture in the low layer from the texture data, including a weighting value used for predicting the picture in the low layer;

calculating at least one weighting factor for the current picture using the weighting value information for the picture in the low layer;

calculating a weighted sum of reference pictures to the current picture using the weighting factor, the reference pictures being in the high layer, and generating a predicted picture for the current picture using the weighted sum of the reference pictures in the high layer; and

reconstructing a residual signal for the current picture from the texture data and adding the reconstructed residual signal to the predicted picture,

wherein the reference pictures are different than the picture in the low layer,

wherein the picture in the low layer is the picture having a closest temporal position to the current picture in the high layer, and

wherein the picture in the low layer is not a picture having a same temporal position as the current picture in the high layer.

11. The method of claim 10 , wherein the information concerning the picture in the low layer contains a base picture corresponding to the current picture and reference pictures for the base picture.

12. The method of claim 11 , wherein the reference pictures for the base picture are pictures motion-compensated by motion vectors from the base picture.

13. The method of claim 11 , wherein the extracting of the texture data and motion data, the reconstructing of the information about the picture in the low layer, the calculating of the weighting factor, the calculating of the weighted sum of reference pictures, and the reconstructing of the residual signal are performed if the current picture has a same reference scheme and reference distance as the base picture.

14. The method of claim 11 , wherein the calculating of the weighting factor and the calculating of the weighted sum of reference pictures are performed in units of one of a picture, a slice, a macroblock, and a motion block.

15. The method of claim 10 , wherein the calculating of the weighted sum of reference pictures comprises:

if one reference picture exists for the current picture, calculating a product of the weighting factor and the reference picture for the current picture; and

if a plurality of reference pictures exist for the current picture, multiplying appropriate weighting factors by the plurality of reference pictures, respectively, and adding the products together.

16. A non-transitory computer readable medium having stored therein a program for making a computer execute operations of a video encoder for performing weighted prediction on a current picture in a high layer using information concerning a picture in a low layer, said program including computer executable instructions for:

an element for reading information concerning the picture in the low layer, including a weighting value used for predicting the picture in the low layer;

an element for calculating at least one weighting factor for the current picture using the weighting value information for the picture in the low layer;

an element for calculating a weighted sum of reference pictures for the current picture using the weighting factor, the reference pictures being in the high layer, and generating a predicted picture for the current picture using the weighted sum of the reference pictures in the high layer; and

an element for encoding a difference between the current picture and the predicted picture,

wherein the reference pictures are different than the picture in the low layer,

wherein the picture in the low layer is the picture having a closest temporal position to the current picture in the high layer, and

wherein the picture in the low layer is not a picture having a same temporal position as the current picture in the high layer.

17. A non-transitory computer readable medium having stored therein a program for making a computer execute operations of a video decoder for performing weighted prediction on a current picture in a high layer using information concerning a picture in a low layer, said program including computer executable instructions for:

an element for extracting texture data and motion data from an input bitstream;

an element for reconstructing information about the picture in the low layer from the texture data, including a weighting value used for predicting the picture in the low layer;

an element for calculating at least one weighting factor the current picture using the weighting value information for the picture in the low layer;

an element for generating a predicted picture for the current picture by calculating a weighted sum of reference pictures for the current picture using the weighting factors, the reference pictures being in the high layer; and

an element for adding texture data of the current picture among the texture data to the predicted picture,

wherein the reference pictures are different than the picture in the low layer,

wherein the picture in the low layer is the picture having a closest temporal position to the current picture in the high layer, and

wherein the picture in the low layer is not a picture having a same temporal position as the current picture in the high layer.

18. A method for decoding video contained in an input bitstream by performing weighted prediction on a current picture in a high layer using information about a picture in a low layer, the method comprising:

extracting texture data and motion data from the input bitstream;

reconstructing information about the low layer picture from the texture data;

calculating weighting factors using the information about the low layer picture;

calculating a weighted sum of reference pictures to the current picture using the weighting factors and generating a predicted picture for the current picture; and

reconstructing a residual signal for the current picture from the texture data and adding the reconstructed residual signal to the predicted picture,

wherein the information concerning the low layer picture contains a base picture corresponding to the current picture and reference pictures for the base picture, and

wherein the calculating of the weighting factors comprises:

calculating a weighted sum of reference pictures for the base picture using predetermined coefficients; and

calculating the values of the coefficients that minimize the square of a difference between the base picture and the weighted sum.

19. The method of claim 18 , wherein the coefficients include forward and backward coefficients.

20. The method of claim 19 , wherein a sum of the forward and backward coefficients is 1.