Method and apparatus for determining a second picture for temporal direct-mode block prediction

Abstract

A method for determining a first and a second reference picture used for inter-prediction of a macroblock, comprising the steps of (A) finding a co-located picture and block, (B) determining a reference index, (C) mapping the reference index to a lowest valued reference index in a current reference list and (D) using the reference index to determine the second reference picture.

1 . A method for determining a plurality of reference pictures of a current block, comprising the steps of:
 (A) determining a first reference picture of a co-located block of said current block, wherein an identifier is associated with said first reference picture;   (B) mapping a reference index to a lowest valued reference index associated with said identifier, wherein said identifier is associated with said first reference picture from (i) when said first reference picture was used to inter-predict said co-located block to (ii) when said first reference picture is made available as a potential reference picture to inter-predict said current block; and   (C) inter-predicting said current block using (i) said first reference picture associated with said lowest valued reference index and (ii) a second reference picture comprising said co-located block.   
     
     
         2 . The method according to  claim 1 , wherein said current block comprises an H.264 direct-mode macroblock or an H.264 direct-mode macroblock partition. 
     
     
         3 . The method according to  claim 1 , wherein step (B) further comprises:
 storing a respective identifier associated with each of said reference pictures.   
     
     
         4 . The method according to  claim 1 , wherein said first reference picture resides in a first list of said current block and said second reference picture resides in a second list of said current block. 
     
     
         5 . The method according to  claim 1 , wherein said inter-predicting operates on (i) a macroblock when in a first configuration and (ii) a macroblock partition when in a second configuration. 
     
     
         6 . The method according to  claim 1 , wherein step (B) comprises:
 searching for said lowest valued reference index identified by said identifier; and   returning a value of said lowest valued reference index.   
     
     
         7 . The method according to  claim 1 , wherein said method further comprising the step of:
 implementing an interpolative direct mode prediction and a flexible choice for a picture referenced by a finite index reference.   
     
     
         8 . The method according to  claim 1 , wherein said method is implemented in a video encoder. 
     
     
         9 . The method according to  claim 1 , wherein said method is implemented in a video decoder. 
     
     
         10 . An apparatus comprising:
 a circuit configured to (i) determine a first reference picture of a co-located block of a current block, wherein an identifier is associated with said first reference picture, (ii) map a reference index to a lowest valued reference index associated with said identifier, wherein said identifier is associated with said first reference picture from (a) when said first reference picture was used to inter-predict said co-located block to (b) when said first reference picture is made available as a potential reference picture to inter-predict said current block and (iii) inter-predict said current block using (a) said first reference picture associated with said lowest valued reference index and (b) a second reference picture comprising said co-located block.   
     
     
         11 . The apparatus according to  claim 10 , wherein said current block comprises an H.264 direct-mode macroblock or an H.264 direct-mode macroblock partition. 
     
     
         12 . The apparatus according to  claim 10 , further comprising a memory configured to store a respective identifier associated with each of said reference pictures. 
     
     
         13 . The apparatus according to  claim 10 , wherein said first reference picture resides in a first list of said current block and said second reference picture resides in a second list of said current block. 
     
     
         14 . The apparatus according to  claim 10 , wherein said inter-prediction operates on (i) a macroblock when in a first configuration and (ii) a macroblock partition when in a second configuration. 
     
     
         15 . The apparatus according to  claim 10 , wherein said map (i) searches for said lowest valued reference index identified by said identifier and (ii) returns a value of said lowest valued reference index. 
     
     
         16 . The apparatus according to  claim 10 , wherein said circuit is further configured to implement an interpolative direct mode prediction and a flexible choice for a picture referenced by a finite index reference. 
     
     
         17 . The apparatus according to  claim 10 , wherein said apparatus is implemented in a video encoder. 
     
     
         18 . The apparatus according to  claim 10 , wherein said apparatus is implemented in a video decoder. 
     
     
         19 . The apparatus according to  claim 10 , further comprising a content addressable memory configured to store said reference pictures. 
     
     
         20 . An apparatus comprising:
 means for determining a first reference picture of a co-located block of a current block, wherein an identifier is associated with said first reference picture;   means for mapping a reference index to a lowest valued reference index associated with said identifier, wherein said identifier is associated with said first reference picture from (i) when said first reference picture was used to inter-predict said co-located block to (ii) when said first reference picture is made available as a potential reference picture to inter-predict said current block; and   means for inter-predicting said current block using (i) said first reference picture associated with said lowest valued reference index and (ii) a second reference picture comprising said co-located block.