| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a dynamic image decoding method where it becomes clear whether or not a direct mode can be applied, prediction efficiency is improved, and the amount of data can be reduced.SOLUTION: Information indicating whether or not a backward reference frame set by default can be utilized for a direct mode is provided to a decoder. Also, a switching procedure to switch to an alternative method applicable when a collocated block has no effectively usable forward motion vector, and the alternative method are provided. Thereby, it can be clearly determined whether or not the reference frame can be utilized for the direct mode. Furthermore, when a frame number does not have time information, information indicating relation between the reference frame and a current frame can be efficiently transmitted. Moreover, prediction performance when the direct mode cannot be applied can be improved by an alternative mode and its switching procedure.</p> |
