A method for transcoding a predictively-coded object-based picture signal representing a group of pictures to a predictively-coded block-based picture signal representing the group of pictures, the method comprising: extracting a coded scene descriptor and coded object descriptors from the predictively-coded object-based picture signal and decoding the coded scene descriptor to generate a scene descriptor; partially decoding coded object descriptors to generate respective partially-decoded object descriptors, the partially decoding comprising extracting coding information that describes coding of the coded object descriptors; in response to the scene descriptor, generating from the partially decoded object descriptors blocks of a partially-encoded block-based picture signal representing one of the pictures as a current picture, wherein generating the blocks of the partially-encoded block-based picture signal includes dividing the current picture into blocks for block-based coding and generating a visibility and coding table for the current picture from the coding information, wherein the visibility and coding table includes an entry for each block into which the current picture is divided for block-based coding, the entry including coding information for each of the objects that appears in the block; and generating a frame of the predictively-coded block-based picture signal representing the current picture by predictively coding, in response to at least part of the coding information, the partially-encoded block-based picture signal, wherein, in generating the frame of the partially-encoded block-based picture signal, the partially-encoded block-based picture signal is predictively coded in response to the coding information included in the visibility and coding table. extracting a coded scene descriptor and coded object descriptors from the predictively-coded object-based picture signal and decoding the coded scene descriptor to generate a scene descriptor; partially decoding coded object descriptors to generate respective partially-decoded object descriptors, the partially decoding comprising extracting coding information that describes coding of the coded object descriptors; in response to the scene descriptor, generating from the partially decoded object descriptors blocks of a partially-encoded block-based picture signal representing one of the pictures as a current picture, wherein generating the blocks of the partially-encoded block-based picture signal includes dividing the current picture into blocks for block-based coding and generating a visibility and coding table for the current picture from the coding information, wherein the visibility and coding table includes an entry for each block into which the current picture is divided for block-based coding, the entry including coding information for each of the objects that appears in the block; and generating a frame of the predictively-coded block-based picture signal representing the current picture by predictively coding, in response to at least part of the coding information, the partially-encoded block-based picture signal, wherein, in generating the frame of the partially-encoded block-based picture signal, the partially-encoded block-based picture signal is predictively coded in response to the coding information included in the visibility and coding table.