1. A video decoding method, comprising: receiving, by a decoding apparatus, and identifying dependency information through a video parameter set (VPS) extension syntax, wherein the dependency information indicates a dependency type for a current layer; performing, by the decoding apparatus, inter-layer prediction for a current block based on the dependency information; and reconstructing, by the decoding apparatus, a current picture based on the result of the inter-layer prediction, wherein the dependency information indicates the dependency type among 1) a first dependency type representing a reference layer is available for inter-layer sample prediction of the current layer but is unavailable for inter-layer motion prediction of the current layer, 2) a second dependency type representing the reference layer is available for inter-layer motion prediction but is unavailable for inter-layer sample prediction, 3) a third dependency type representing the reference layer is available for both inter-layer motion prediction and inter-layer sample prediction of the current layer.