Moving image prediction encoding/decoding system

A video predictive decoding device comprising:

• a processor;
• an input terminal executable by the processor to accept input of compressed picture data including a random access picture serving as a picture of random access, the compressed picture data obtained by encoding each of a plurality of pictures constituting a video sequence by a method of either intra-frame prediction or inter-frame prediction, and the input terminal further executable by the processor to accept input of display order encoded data obtained by encoding data providing display order information of each of the pictures;
• a restoration unit executable by the processor to decode the compressed picture data and restore a plurality of reproduced pictures, the restoration unit further executable by the processor to decode the display order encoded data to restore the display order information;
• and
• a frame memory to store the restored reproduced pictures as reference pictures, the reference pictures available for decoding of a subsequent picture in decoding order,
• wherein the restoration unit is further executable by the processor to decode display order information and reference picture information of each of the pictures included in the compressed picture data,
• wherein the restoration unit is further executable by the processor to decode a first picture in accordance with the reference picture information using the reference picture, the first picture preceding the random access picture in display order and following the random access picture in decoding order, and decode a second picture that follows the random access picture in display order, the second picture decoded in accordance with the reference picture information using the random access picture as a reference picture without reference to any reference pictures preceding the random access picture in decoding order or in display order, and
• wherein immediately before the restoration unit decodes the second picture that follows the random access picture in display order, the frame memory is refreshed by setting every reference picture stored in the frame memory except for the random access picture, as not used as reference pictures.

A video predictive encoding method to be executed by a video predictive encoding device with a frame memory to store reference pictures used to encode a subsequent picture, comprising:

• accepting, at the video predictive encoding device, input of a plurality of pictures constituting a video sequence;
• encoding, by the video predictive encoding device, each of the input pictures by either intra-frame prediction or inter-frame prediction to generate compressed picture data for each of the input pictures, the input pictures including a random access picture serving as a picture of random access, and encoding data providing display order information of each of the input pictures;
• decoding, by the video predictive encoding device, the generated compressed picture data to restore a plurality of reproduced pictures;
• and
• storing, by the video predictive encoding device, the restored reproduced pictures in the frame memory as the reference pictures used to encode the subsequent picture, and
• wherein decoding, by the video predictive encoding device, the generated compressed picture data further comprises, decoding display order information and reference picture information of each of the pictures included in the compressed picture data,
• wherein encoding, by the video predictive encoding device, comprises encoding, in accordance with the reference picture information, a first picture using the reference picture, the first picture preceding the random access picture in display order and following the random access picture in encoding order, and encoding a second picture that follows the random access picture in display order using the random access picture as a reference picture without reference to any reference pictures preceding the random access picture in encoding order or in display order, and
• wherein immediately before encoding the second picture that follows the random access picture in display order, the frame memory is refreshed by setting every reference picture stored in the frame memory except for the random access picture, as not used as reference pictures.

A video predictive decoding method to be executed by a video predictive decoding device with a frame memory to store reference pictures used to decode a subsequent picture, comprising:

• accepting, at the video predictive decoding device, input of compressed picture data including a random access picture serving as a picture of random access, the compressed picture data obtained by encoding each of a plurality of pictures constituting a video sequence by either intra-frame prediction or inter-frame prediction;
• accepting, by the video predictive decoding device, input of display order encoded data obtained by encoding data providing display order information of each of the pictures;
• decoding the compressed picture data with the video predictive decoding device to restore reproduced pictures, and decoding with the video predictive decoding device the display order encoded data to restore the display order information;
• and
• storing, in the frame memory, the restored reproduced pictures as the reference pictures, the reference pictures available for decoding of the subsequent picture, and
• wherein decoding further comprises decoding reference picture information of each of the pictures included in the compressed picture data,
• wherein decoding further comprises decoding, in accordance with the reference picture information, a first picture using the reference picture, the first picture preceding the random access picture in display order and following the random access picture in decoding order, and a second picture that follows the random access picture in display order using the random access picture as a reference picture without reference to any reference pictures preceding the random access picture in decoding order or in display order, and
• wherein immediately before decoding the second picture that follows the random access picture in display order, the frame memory is refreshed by setting every reference picture stored in the frame memory except for the random access picture, as not used as reference pictures.