Dynamic image predictive encoding and decoding device, method, and program

A video predictive decoding method executed by a video predictive decoding device, comprising:

• inputting a bitstream including compressed picture data of a plurality of pictures constituting a video sequence, where each picture has a network abstraction layer unit type that identifies said picture as one of a plurality of picture types including a random access picture, a random access skipped (RAS) leading picture and anon-RAS leading picture;
• decoding the compressed picture data to reconstruct the plurality of pictures based on their picture types;
• and
• outputting the reconstructed pictures;
• wherein
• 1) the random access picture is the first picture in the bitstream in a decoding order when the decoding process, which starts at any random access picture in the bitstream, is started from said random access picture;
• 2) the RAS leading picture is g picture which precedes an associated random access picture in an output order, and is not decodable when the associated random access picture is the first picture in the bitstream in decoding order,
• 3) the non-RAS leading picture is g picture which precedes an associated random access picture in the output order, and is decodable,
• and wherein
• a reference picture set that includes reference pictures used for inter prediction of the non-RAS leading picture does not include any of a RAS leading picture or a picture that precedes the associated random access picture in the decoding order,
• the bitstream includes a first random access picture and a second random access picture amid the bitstream, the first random access picture preceding the second random access picture in the decoding order, and a reference picture set used for inter prediction of a picture associated with the second random access picture includes at least one picture that resides in the decoding order between the first and second random access pictures but includes no picture that precedes the first random access picture in the decoding order, and
• decoding the compressed picture data comprising the video predictive decoding device determining whether a picture in the plurality of pictures is correctly decoded, at a start of decoding of said picture.