Image decoding method and apparatus using same
The present invention includes an image information decoding method which comprises: a step of receiving a bitstream that includes a network abstraction layer (NAL) unit including information related to an encoded image; and a step of parsing an NAL unit header of the NAL unit. The NAL unit header includes layer information including reserved_one_5bits for identifying an extended layer in an extended bitstream and temporal_id for identifying a temporal layer of a bitstream. The reserved_one_5bits of the layer information is received prior to the temporal_id of the layer information. Thus, a method for describing scalability information in a hierarchical bitstream is provided.
1. A method of decoding video, the method comprising:
receiving, by a decoding apparatus, a bitstream comprising a network abstraction layer (NAL) unit including information on an encoded picture;
obtaining, by the decoding apparatus, NAL unit type information from a NAL unit header of the NAL unit;
specifying, by the decoding apparatus, a NAL unit type of the current picture based on the NAL unit type information; and
decoding, by the decoding apparatus, a current picture based on the NAL unit type,
wherein the NAL unit type for the current picture is one of NAL unit types including a clean random access (CRA) type to specify a CRA picture and a broken link access (BLA) type to specify a BLA picture,
wherein the CRA picture is a random access point picture and the CRA picture has a uniform NAL unit type regardless of a type of a leading picture associated with the CRA picture, wherein an output order of the leading picture is prior to an output order of the CRA picture.
2. The method of claim 1 , wherein the leading picture is one of a first leading picture to be skipped for outputting or a second leading picture to be decoded.
3. The method of claim 2 , wherein the first leading picture is not present after the BLA picture.
4. The method of claim 1 , wherein the step of decoding the current picture comprises decoding I slices when the current picture is the CRA picture or the BLA picture.
5. The method of claim 2 , wherein the first leading picture is neither decoded nor output.
6. The method of claim 1 , wherein the NAL unit header includes extended layer information to define layer identification for an extended layer and temporal layer information to identify a temporal layer, and
wherein, in the NAL unit header, the extended layer information is signaled or parsed before the temporal layer information.
7. The method of claim 1 , wherein the BLA picture is present in a middle of the bitstream of a coded video sequence as a random access point when pictures in the coded video sequence are spliced or the bitstream is broken in the middle.