Method and apparatus for encoding/decoding multilayer video signal

1. A method for decoding a multi-layer video signal, the method comprising:

determining whether all candidate reference pictures of a current picture are used for inter-layer prediction of the current picture in a current layer, based on an all active flag;

determining number of active references for the current picture of the current layer based on number of all candidate reference pictures if it is determined that all candidate reference pictures are used for inter-layer prediction of the current picture;

determining number of active references for the current picture of the current layer in consideration of whether a maximum number of active reference pictures for the current picture is limited, if it is determined that all candidate reference pictures are not applied to inter-layer prediction of the current picture;

acquiring a reference layer Identifier (ID) based on the determined number of active references;

determining an active reference picture for the current picture using the reference layer ID;

generating an inter-layer reference picture by upsampling the active reference picture; and

performing inter-layer prediction for the current picture, using the inter-layer reference picture,

wherein it is determined whether the maximum number of active reference pictures for the current picture is limited, based on a maximum active reference flag,

wherein the maximum active reference flag equals to a first value specifies that the number of active reference pictures available for inter-layer prediction of each picture of the video sequence is limited to 1, and the maximum active reference flag equals to a second value specifies that a plurality of active reference pictures are available for inter-layer prediction of each picture of the video sequence, and

wherein if the maximum number of active reference pictures is limited to 1 according to the maximum active reference flag, the number of active references is determined according to the limited maximum number of active reference pictures.

2. The method according to claim 1 , wherein the performing of inter-layer prediction for the current picture comprises:

acquiring spatial offset information including at least one of a segment offset and a block offset;

determining a reference block for use in inter-layer prediction of a current block in the current picture based on the spatial offset information; and

estimating a sample value of the current block based on the determined reference block.

3. An apparatus for decoding a multi-layer video signal, the apparatus comprising:

a memory configured to store pictures of reference layers for inter layer-prediction; and

a prediction unit including an inter-layer prediction unit for performing inter-layer prediction for a current layer using a corresponding picture of a reference layer received from the memory, the inter-layer prediction unit is configured to,

determine whether all candidate reference pictures of a current picture are used for inter-layer prediction of the current picture in a current layer, based on an all active flag;

determine number of active references for the current picture of the current layer based on number of all candidate reference pictures if it is determined that all candidate reference pictures are used for inter-layer prediction of the current picture;

determine number of active references for a current picture of a current layer in consideration of whether a maximum number of active reference pictures for the current picture is limited,

acquire a reference layer Identifier (ID) based on the determined number of active references,

determine an active reference picture for the current picture using the reference layer ID,

generate an inter-layer reference picture by upsampling the active reference picture, and

perform inter-layer prediction for the current picture, using the inter-layer reference picture,

wherein it is determined whether the maximum number of active reference pictures for the current picture is limited, based on a maximum active reference flag,

wherein the maximum active reference flag equals to a first value specifies that the number of active reference pictures available for inter-layer prediction of each picture of the video sequence is limited to 1, and the maximum active reference flag equals to a second value specifies that a plurality of active reference pictures are available for inter-layer prediction of each picture of the video sequence, and

wherein if the maximum number of active reference pictures is limited to 1 according to the maximum active reference flag, the prediction unit determines the number of active references according to the limited maximum number of active reference pictures.

4. The apparatus according to claim 3 , wherein the prediction unit acquires spatial offset information including at least one of a segment offset and a block offset, determines a reference block for use in inter-layer prediction of a current block in the current picture based on the spatial offset information, and estimates a sample value of the current block based on the determined reference block.

5. A method for encoding a multi-layer video signal, the method comprising:

determining whether all candidate reference pictures of a current picture are used for inter-layer prediction of the current picture in a current layer, based on an all active flag;

determining number of active references for the current picture of the current layer based on number of all candidate reference pictures if it is determined that all candidate reference pictures are used for inter-layer prediction of the current picture;

determining number of active references for a current picture of a current layer in consideration of whether a maximum number of active reference pictures for the current picture is limited if it is determined that all candidate reference pictures are not applied to inter-layer prediction of the current picture;

acquiring a reference layer Identifier (ID) based on the determined number of active references;

determining an active reference picture for the current picture using the reference layer ID;

generating an inter-layer reference picture by upsampling the active reference picture; and

performing inter-layer prediction for the current picture, using the inter-layer reference picture,

wherein it is determined whether the maximum number of active reference pictures for the current picture is limited, based on a maximum active reference flag,

wherein the maximum active reference flag equals to a first value specifies that the number of active reference pictures available for inter-layer prediction of each picture of the video sequence is limited to 1, and the maximum active reference flag equals to a second value specifies that a plurality of active reference pictures are available for inter-layer prediction of each picture of the video sequence, and

wherein if the maximum number of active reference pictures is limited to 1 according to the maximum active reference flag, the number of active references is determined according to the limited maximum number of active reference pictures.

6. The method according to claim 5 , wherein the performing of inter-layer prediction for the current picture comprises:

acquiring spatial offset information including at least one of a segment offset and a block offset;

determining a reference block for use in inter-layer prediction of a current block in the current picture based on the spatial offset information; and

estimating a sample value of the current block based on the determined reference block.

7. An apparatus for encoding a multi-layer video signal, the apparatus comprising:

a memory configured to store pictures of reference layers for inter layer-prediction; and

a prediction unit including an inter-layer prediction unit for performing inter-layer prediction for a current layer using a corresponding picture of a reference layer received from the memory, the inter-layer prediction unit is configured to,

determine whether all candidate reference pictures of a current picture are used for inter-layer prediction of the current picture in a current layer, based on an all active flag;

determine number of active references for the current picture of the current layer based on number of all candidate reference pictures if it is determined that all candidate reference pictures are used for inter-layer prediction of the current picture;

determine number of active references for a current picture of a current layer in consideration of whether a maximum number of active reference pictures for the current picture is limited,

acquire a reference layer Identifier (ID) based on the determined number of active references,

determine an active reference picture for the current picture using the reference layer ID,

generate an inter-layer reference picture by upsampling the active reference picture, and

perform inter-layer prediction for the current picture, using the inter-layer reference picture,

wherein it is determined whether the maximum number of active reference pictures for the current picture is limited, based on a maximum active reference flag,

wherein the maximum active reference flag equals to a first value specifies that the number of active reference pictures available for inter-layer prediction of each picture of the video sequence is limited to 1, and the maximum active reference flag equals to a second value specifies that a plurality of active reference pictures are available for inter-layer prediction of each picture of the video sequence, and

wherein if the maximum number of active reference pictures is limited to 1 according to the maximum active reference flag, the prediction unit determines the number of active references according to the limited maximum number of active reference pictures.

8. The apparatus according to claim 7 , wherein the inter-layer prediction unit perform the inter-layer prediction by acquiring spatial offset information including at least one of a segment offset and a block offset, determining a reference block for use in inter-layer prediction of a current block in the current picture based on the spatial offset information, and estimating a sample value of the current block based on the determined reference block.

9. The method according to claim 1 ,

wherein the inter-layer prediction is performed by a reference picture list, the reference picture list is constructed in the sequence of a first short-term reference picture, the inter-layer reference picture, a second short-term reference picture, and a long-term reference picture,

wherein the first short-term reference picture has an output order (POC) value less than that of the current picture, the second short-term reference picture has an output order (POC) value greater than that of the current picture.

10. The method according to claim 1 ,

wherein the inter-layer prediction is performed by a reference picture list, the reference picture list is composed of a reference picture list 0 and a reference picture list 1 ,

wherein the reference picture list 0 is constructed in the sequence of a first short-term reference picture, the inter-layer reference picture, a second short-term reference picture, and a long-term reference picture, and the reference picture list 1 is constructed in the sequence of a second short-term reference picture, the inter-layer reference picture, a first short-term reference picture, and a long-term reference picture

wherein the first short-term reference picture has an output order (POC) value less than that of the current picture, the second short-term reference picture has an output order (POC) value greater than that of the current picture.

11. The apparatus according to claim 3 ,

wherein the inter-layer prediction is performed by a reference picture list, the reference picture list is constructed in the sequence of a first short-term reference picture, the inter-layer reference picture, a second short-term reference picture, and a long-term reference picture,

wherein the first short-term reference picture has an output order (POC) value less than that of the current picture, the second short-term reference picture has an output order (POC) value greater than that of the current picture.

12. The apparatus according to claim 3 ,

wherein the inter-layer prediction is performed by a reference picture list, the reference picture list is composed of a reference picture list 0 and a reference picture list 1 ,

wherein the reference picture list 0 is constructed in the sequence of a first short-term reference picture, the inter-layer reference picture, a second short-term reference picture, and a long-term reference picture, and the reference picture list 1 is constructed in the sequence of a second short-term reference picture, the inter-layer reference picture, a first short-term reference picture, and a long-term reference picture

wherein the first short-term reference picture has an output order (POC) value less than that of the current picture, the second short-term reference picture has an output order (POC) value greater than that of the current picture.