Method and apparatus for generating a motion vector

Abstract

One embodiment provides a method of generating a motion vector associated with a current block in a first picture layer. In this embodiment, motion vector information for a block in a second picture layer is obtained. The second picture layer has lower quality pictures than pictures in the first picture layer, and the block of the second picture layer is temporally associated with the current block in the first picture layer. Motion vector difference information associated with the current block in the first picture layer is also obtained. The motion vector associated with the current block in the first picture layer is generated based on the obtained motion vector information and the obtained motion vector difference information.

1 . A method of generating a motion vector associated with a current block in a first picture layer, comprising: 
 obtaining motion vector information for a block in a second picture layer, the second picture layer having lower quality pictures than pictures in the first picture layer, and the block of the second picture layer being temporally associated with the current block in the first picture layer;    obtaining motion vector difference information associated with the current block in the first picture layer; and    generating the motion vector associated with the current block in the first picture layer based on the obtained motion vector information and the obtained motion vector difference information.    
   
   
       2 . The method of  claim 1 , wherein the obtaining motion vector information step obtains the motion vector information from the second picture layer.  
   
   
       3 . The method of  claim 2 , wherein the obtaining the motion vector difference information step obtains the motion vector difference information from the first picture layer.  
   
   
       4 . The method of  claim 1 , wherein the obtaining the motion vector difference information step obtains the motion vector difference information from the first picture layer.  
   
   
       5 . The method of  claim 1 , wherein the motion vector information includes a motion vector associated with the block of the second picture layer.  
   
   
       6 . The method of  claim 1 , wherein the generating step comprises: 
 determining a motion vector prediction based on the obtained motion vector information; and    generating the motion vector associated with the current block in the first picture layer based on the motion vector prediction and the obtained motion vector difference information.    
   
   
       7 . The method of  claim 6 , wherein 
 the motion vector information includes a motion vector associated with the block of the second picture layer; and    the determining a motion vector prediction step determines the motion vector prediction equal to the motion vector associated with the block of the second picture layer.    
   
   
       8 . The method of  claim 6 , wherein the generating step generates the motion vector associated with the current block equal to the motion vector prediction plus a motion vector difference indicated by the motion vector difference information.  
   
   
       9 . The method of  claim 8 , wherein 
 the motion vector information includes a motion vector associated with the block of the second picture layer; and    the determining a motion vector prediction step determines the motion vector prediction equal to the motion vector associated with the block of the second picture layer.    
   
   
       10 . The method of  claim 1 , wherein the motion vector difference information indicates a motion vector difference of a one-quarter pixel or less.  
   
   
       11 . The method of  claim 1 , wherein the motion vector difference information indicates a motion vector difference of a one-half pixel or less.  
   
   
       12 . The method of  claim 1 , wherein the generated motion vector points to a block in a reference picture for the current block.  
   
   
       13 . The method of  claim 12 , wherein the reference picture is a picture in the first picture layer.  
   
   
       14 . The method of  claim 13 , wherein the reference picture for the current block is temporally associated with a reference picture in the second picture layer, the reference picture in the second picture layer being a reference picture for the block in the second picture layer.  
   
   
       15 . An apparatus for generating a motion vector associated with a current block in a first picture layer, comprising: 
 a first decoder obtaining motion vector information for a block in a second picture layer, the second picture layer having lower quality pictures than pictures in the first picture layer, and the block of the second picture layer being temporally associated with the current block in the first picture layer; and    a second decoder obtaining motion vector difference information associated with the current block in the first picture layer, and generating the motion vector associated with the current block in the first picture layer based on the obtained motion vector information and the obtained motion vector difference information.