Multi-layer video coding method for random access and device therefor, and multi-layer video decoding method for random access and device therefor

1. A video decoding method performed by a video decoding apparatus, the method comprising:

obtaining Random Access Point (RAP) picture information of a plurality of layers comprising a base layer and an enhancement layer, from a bitstream, the RAP picture information indicating whether RAP pictures of the base layer and RAP pictures of the enhancement layer are aligned with the same POC (Picture Order Count) order;

decoding the RAP pictures of the base layer based on a POC order of the base layer; when the RAP picture information indicates that the RAP pictures of the base layer and the RAP pictures of the enhancement layer are aligned with the same POC order, decoding the RAP pictures of the enhancement layer based on the POC order of the base layer; and

when the RAP picture information indicates that the RAP pictures of the base layer and the RAP pictures of the enhancement layer are not aligned with the same POC order, decoding the RAP pictures of the enhancement layer independently from the POC order of the base layer.

2. The method of claim 1 , wherein the decoding the RAP pictures of the enhancement layer based on the RAP picture information comprises, when a picture of the enhancement layer at a Picture Order Count (POC) which is a random access point, is a non-RAP picture, decoding a RAP picture that occurs after the non-RAP picture in a POC order.

3. The method of claim 1 , wherein the RAP picture information comprises an identifier indicating a type of a RAP picture at the same Picture Order Count (POC) of the plurality of layers.

4. The method of claim 1 , wherein the RAP picture information is included in one of a parameter set, an Access Unit Delimiter (AUD), and Supplemental Enhancement Information (SEI).

5. The method of claim 1 , wherein the decoding the RAP pictures of the enhancement layer based on the RAP picture information comprises, when a Random Access Skip Leading (RASL) picture of a reference layer is not decoded, not decoding a picture that refers to the RASL picture.

6. The method of claim 1 , wherein a temporal identifier of a picture included in the enhancement layer has a value greater than or equal to a temporal identifier of a reference picture included in the base layer.

7. The method of claim 1 , wherein at least one from among Instantaneous Decoding Refresh (IDR), Clean Random Access (CRA), and Broken Link Access (BLA) pictures of the base layer is used as the RAP picture of the base layer.

8. The method of claim 1 , wherein at least one from among Instantaneous Decoding Refresh (IDR), Clean Random Access (CRA), and Broken Link Access (BLA) pictures of the enhancement layer is used as at least one from among a bit stream extraction point picture and a layer switching point picture.

9. The method of claim 1 , further comprising splicing one of the plurality of layers independently from the other layers in the plurality of layers.

10. A video encoding method, comprising:

when RAP pictures of a base layer and RAP pictures of an enhancement layer are aligned with the same POC order, determining RAP picture information to indicate that the RAP pictures of the enhancement layer encoded based on a POC order of the base layer; and

when the RAP pictures of the base layer and the RAP pictures of the enhancement layer are not aligned with the same POC order, determining the RAP picture information to indicate that the RAP pictures of the enhancement layer independently encoded from the POC order of the base layer,

encoding pictures of an image sequence to a plurality of layers comprising the base layer and the enhancement layer to generate Random Access Point (RAP) picture information about the plurality of layers, the RAP picture information indicating whether RAP pictures of the base layer and RAP pictures of the enhancement layer are aligned with the same POC (Picture Order Count) order; and

generating a bitstream comprising the RAP picture information.

11. The method of claim 10 , wherein the RAP picture information includes an identifier indicating a type of a RAP picture existing at a same Picture Order Count (POC) of the plurality of layers.

12. A video decoding apparatus, comprising:

a receiver configured to receive a bitstream; and

a decoder configured to:

obtain, from the bitstream, Random Access Point (RAP) picture information of a plurality of layers comprising a base layer and an enhancement layer the RAP picture information indicating whether RAP pictures of the base layer and RAP pictures of the enhancement layer are aligned with the same POC (Picture Order Count) order,

decode the RAP pictures of the base layer based on a POC order of the base layer, decode the RAP pictures of the enhancement layer based on the POC order of the base layer, when the RAP picture information indicates that the RAP pictures of the base layer and the RAP pictures of the enhancement layer are aligned with the same POC order, and

decode the RAP pictures of the enhancement layer independently from the POC order of the base layer, when the RAP picture information indicates that the RAP pictures of the base layer and the RAP pictures of the enhancement layer are not aligned with the same POC order.

13. A video encoding apparatus, comprising:

an encoder configured to:

when RAP pictures of a base layer and RAP pictures of an enhancement layer are aligned with the same POC order, determine RAP picture information to indicate that the RAP pictures of the enhancement layer encoded based on a POC order of the base layer,

when the RAP pictures of the base layer and the RAP pictures of the enhancement layer are not aligned with the same POC order, determine the RAP picture information to indicate that the RAP pictures of the enhancement layer independently encoded from the POC order of the base layer, and

encode pictures of an image sequence to a plurality of layers comprising the base layer and the enhancement layer to generate Random Access Point (RAP) picture information about the plurality of layers, the RAP picture information indicating whether RAP pictures of the base layer and RAP pictures of the enhancement layer are aligned with the same POC (Picture Order Count) order; and

an output unit configured to generate a bitstream comprising the RAP picture information.

14. A non-transitory computer readable recording medium having recorded thereon a program for implementing the method of claim 1 .