Moving picture encoding method and decoding method
Conventionally, there has been a case that the direct mode cannot be applied effectively depending on the block. With such being the case, information indicating whether a backward reference frame set by default can be utilized in the direct mode is provided to a decoder. A switching procedure to switch to a compensation method applicable when a collocated block has no forward motion vector for effective use, and the compensation method are also provided to the decoder. Thus, it is possible to clearly determine whether the reference frame can be used in the direct mode. Further, when the frame number has no time information, it is possible to effectively send information indicating the relationship between the reference frame and the current frame. Furthermore, the alternative mode and its switching procedure of the present invention make it possible to improve the prediction performance when the direct mode cannot be applied.
1. A moving picture decoding method, carried out by a computing system, which generates a predicted image using motion vector information and reference frame(s) information, comprising:
in a prediction mode in which prediction mode motion vector information of a current block in a current frame has not been transmitted from an encoding side:
selecting, from among multiple candidate reference frames, a frame(s) to be referenced to in the prediction mode; and
determining motion vector information to be used for the current block in the prediction mode, based on whether predetermined adjacent blocks adjacent to the current block, have a motion vector, wherein all of the predetermined adjacent blocks and the current block belong to the current frame and the predetermined adjacent blocks are decoded earlier than the current block; and
performing moving picture decoding by generating said predicted image using the reference frame(s) information on said selected reference frame(s) and the motion vector information in said prediction mode.
2. A moving picture decoding method, carried out by a computing system, which generates a predicted image using motion vector information and reference picture(s) information, comprising:
in a prediction mode in which prediction mode motion vector information of a current block in a current frame has not been transmitted from an encoding side:
selecting, from among multiple candidate reference pictures, a picture(s) to be referenced to in the prediction mode; and
determining motion vector information to be used for the current block in the prediction mode, based on an availability of motion vector(s) of predetermined adjacent blocks which are adjacent to a current block, wherein all of the predetermined adjacent blocks and the current block belong to the current picture and the predetermined adjacent blocks are decoded earlier than the current block; and
performing moving picture decoding by generating said predicted image using the reference picture(s) information on said selected reference picture(s) and the motion vector information in said prediction mode.
3. A moving picture decoding method, carried out by a computing system, which generates a predicted image using motion vector information, comprising:
in a decoding of a motion-vector-less block from a motion-vector-less prediction mode:
determining motion vector information to be used for the decoding of the motion-vector-less block, based on whether predetermined adjacent blocks which are adjacent to the motion-vector-less block, have a motion vector, wherein all of the predetermined adjacent blocks and the motion-vector-less block belong to a same frame and the predetermined adjacent blocks are decoded earlier than the motion-vector-less block; and
performing moving picture decoding by generating said predicted image, by using the motion vector information from the determining operation in the decoding of the motion-vector-less block.
4. A moving picture decoding method as claimed in claim 3 , wherein the motion vector information is a motion vector selected from at least one motion vector of the predetermined adjacent blocks of the same frame.
5. A moving picture decoding method, carried out by a computing system, which generates a predicted image using motion vector information and reference frame(s) information, comprising:
in a prediction mode in which prediction mode motion vector information of a current block in a current frame has not been transmitted from an encoding side:
selecting, from among multiple candidate reference frames, a frame(s) to be referenced to in the prediction mode; and
determining motion vector information to be used for the current block in the prediction mode, based on whether predetermined adjacent blocks adjacent to the current block, have a motion vector referencing to selected reference frame(s) from the selecting, wherein all of the predetermined adjacent blocks and the current block belong to the current frame and the predetermined adjacent blocks are decoded earlier than the current block; and
performing moving picture decoding by generating said predicted image using the reference frame(s) information on said selected reference frame(s) and the motion vector information in said prediction mode.