Image decoding apparatus, image decoding method

Abstract

A layer incapable of being decoded on a bit stream which is generated through a bit stream extraction process from a bit stream including a prescribed layer set and which only includes a layer set made up of a subset of the prescribed layer set, occurs. An aspect of the present disclosure specifies a bit stream constraint pertaining to a parameter set, and a bit stream extraction process.

1 . An image decoding apparatus for decoding input image coded data, comprising:
 an image-coded data extractor that extracts image coded data pertaining to a decoding target layer set including at least one layer, from the input image coded data, based on a layer ID list indicating the decoding target layer set, and, in the case where a layer identifier of a non-VCL NAL unit is not included in the decoding target layer set, rewrites the layer identifier of the non-VCL NAL unit to the lowest layer identifier in the decoding target layer set; and   a picture decoding unit that decodes a picture in the decoding target layer set, from the extracted image coded data,   wherein a non-VCL NAL unit having a layer identifier that is not equal to the lowest layer identifier in an access unit and is not included in the layer ID list is discarded from the input image coded data.   
     
     
         2 . The image decoding apparatus according to  claim 1 , wherein a temporal ID of an NAL unit included in the image coded data is equal to or less than a value of a highest temporal ID of the decoding target layer set. 
     
     
         3 . The image decoding apparatus according to  claim 1 , wherein the non-VCL NAL unit is an NAL unit having a parameter set. 
     
     
         4 . The image decoding apparatus according to  claim 3 , wherein the parameter set includes a video parameter set. 
     
     
         5 . The image decoding apparatus according to  claim 3 , wherein the parameter set includes a sequence parameter set. 
     
     
         6 . The image decoding apparatus according to  claim 3 , wherein the parameter set includes a picture parameter set. 
     
     
         7 . An image decoding method of decoding input image coded data, comprising:
 an image-coded data extracting step of extracting image coded data pertaining to a decoding target layer set including at least one layer, from the input image coded data, based on a layer ID list indicating the decoding target layer set, and, in the case where a layer identifier of a non-VCL NAL unit is not included in the decoding target layer set, rewriting the layer identifier of the non-VCL NAL unit to the lowest layer identifier in the decoding target layer set; and   a picture decoding step of decoding a picture in the decoding target layer set, from the extracted image coded data,   wherein a non-VCL NAL unit having a layer identifier that is not equal to the lowest layer identifier in an access unit and is not included in the layer ID list is discarded from the input image coded data.