Video encoding device, video decoding device, video encoding method, video decoding method, video system, and program

A video decoding device comprising:

• a memory storing software instructions;
• and
• one or more processors configured to execute the software instructions to,
• de-multiplex a maximum image width and a maximum image height of a luminance sample of all frames from a bitstream and de-multiplexing an image width and an image height of the luminance sample for each frame from the bitstream;
• derive a reference picture scale ratio for scaling the image width and the image height of the luminance sample of the frame to be processed to the image width and the image height of the luminance sample of the frame processed in the past;
• and
• scale an image size of the frame to be output for display to be the maximum image width and the maximum image height.

A video encoding method, implemented by a processor, comprising:

• multiplexing a maximum image width and a maximum image height of a luminance sample of all frames into a bitstream;
• deciding an image width and an image height of the luminance sample that is less than or equal to the maximum image width and the maximum image height, for each frame;
• multiplexing the decided image width and the decide image height of the luminance sample into a bitstream;
• and
• deriving a reference picture scale ratio for scaling the image width and the image height of the luminance sample of the frame to be processed to the image width and the image height of the luminance sample of the frame processed in the past.