Determination of a field referencing pattern

Abstract

Several methods and a system to perform determination of a field referencing pattern are disclosed. In one aspect, a method is disclosed. A motion vector of a previously coded frame is analyzed using a processor and a memory. A statistic is updated based on whether the motion vector includes one or more of a fractional pel vertical component, a half pel vertical component, and an integer pel vertical component. A field referencing pattern of a target field is determined based on the statistic and an exception protocol.

What is claimed is: 
     
         1 . A method, comprising:
 analyzing a motion vector of a previously coded frame using a processor and a memory;   updating a statistic based on whether the motion vector is comprised of at least one of a fractional pel vertical component, a half pel vertical component, and an integer pel vertical component; and   determining a field referencing pattern of a target field based on at least one of the statistic and an exception protocol.   
     
     
         2 . The method of  claim 1 , further comprising:
 encoding the target field using the field referencing pattern, the processor, and the memory.   
     
     
         3 . The method of  claim 2 , wherein the field referencing pattern identifies a reference field comprised of at least one of a same parity field and a most recently coded reference field. 
     
     
         4 . The method of  claim 3 , wherein the statistic is determined using at least one of a quantity of the fractional pel vertical component, a quantity of the half pel vertical component, and a quantity of the integer pel vertical component. 
     
     
         5 . The method of  claim 4 , wherein the statistic is comprised of at least one of a half pel ratio and a fractional pel ratio, wherein the half pel ratio is proportional to a number of half pel macroblocks divided by a total number of macroblocks of the previously coded frame and the fractional pel ratio is proportional to a number of fractional pel macroblocks divided by a total number of macroblocks of the previously coded frame. 
     
     
         6 . The method of  claim 5 , wherein the field referencing pattern is changed when at least one of a half pel ratio threshold and a fractional pel ratio threshold is exceeded. 
     
     
         7 . The method of  claim 5 , wherein the field referencing pattern is kept the same when the half pel ratio is lower than a half pel ratio threshold and the fractional pel ratio is lower than a fractional pel ratio threshold. 
     
     
         8 . The method of  claim 6 , wherein the half pel ratio threshold is within a threshold tolerance of 0.5 and the fractional pel ratio threshold is within a threshold tolerance of 0.9. 
     
     
         9 . The method of  claim 2 , wherein the exception protocol determines that the field referencing pattern is a most recently coded reference field when the target field is a bottom field of an intra coded frame. 
     
     
         10 . The method of  claim 2 , wherein the exception protocol determines that the field referencing pattern is a most recently coded reference field when the target field is a bottom field of a P-frame in a sequence comprised of one or more B frames. 
     
     
         11 . The method of  claim 2 , further comprising:
 determining a texture level using a group of pixels of the currently coded frame; and   adapting at least one of a half pel ratio threshold to an alternate half pel ratio threshold and a fractional pel ratio threshold to an alternate fractional pel ratio threshold when the texture level is greater than a texture limit.   
     
     
         12 . The method of  claim 11 , wherein the alternate half pel ratio threshold is within a threshold tolerance of 0.3 and the alternate fractional pel ratio threshold is within a threshold tolerance of 0.7. 
     
     
         13 . The method of  claim 1 , further comprising reordering a reference field list when the field referencing pattern identifies a reference field comprised of a most recently coded reference field. 
     
     
         14 . The method of  claim 12 , further comprising:
 causing a machine to perform the method of  claim 12  by executing a set of instructions embodied by the method of  claim 12  in a form of a machine readable medium.   
     
     
         15 . A system, comprising:
 an aggregation module to analyze a motion vector of a previously coded frame using a processor and a memory;   an evaluation module to update a statistic based on whether the motion vector is comprised of at least one of a fractional pel vertical component, a half pel vertical component, and an integer pel vertical component; and   a selection module to determine a field referencing pattern of a target field based on at least one of the statistic and an exception protocol.   
     
     
         16 . The system of  claim 15 , further comprising:
 a compression module to encode the target field using the field referencing pattern, the processor, and the memory.   
     
     
         17 . The system of  claim 16 , wherein the field referencing pattern identifies a reference field comprised of at least one of a same parity field and a most recently coded reference field. 
     
     
         18 . The system of  claim 17 , wherein the statistic is determined using at least one of a quantity of the fractional pel vertical component, a quantity of the half pel vertical component, and a quantity of the integer pel vertical component. 
     
     
         19 . A method, comprising:
 analyzing a motion vector of a previously coded frame using a processor and a memory;   updating a statistic based on a quantity of motion vectors that are comprised of at least one of a fractional pel vertical component, a half pel vertical component, and an integer pel vertical component, wherein the statistic is comprised of at least one of a half pel ratio and a fractional pel ratio, wherein the half pel ratio is proportional to a number of half pel macroblocks divided by a total number of macroblocks of the previously coded frame and the fractional pel ratio is proportional to a number of fractional pel macroblocks divided by a total number of macroblocks of the previously coded frame;   determining a texture level using a group of pixels of the currently coded frame;   adapting at least one of a half pel ratio threshold to an alternate half pel ratio threshold and a fractional pel ratio threshold to an alternate fractional pel ratio threshold when the texture level is greater than a texture limit;   determining a field referencing pattern of a target field based on at least one of the statistic and an exception protocol, wherein the field referencing pattern identifies a reference field comprised of at least one of a same parity field and a most recently coded reference field; and   encoding the target field using the field referencing pattern.   
     
     
         20 . The method of  claim 19 , wherein the field referencing pattern is changed when at least one of a half pel ratio threshold and a fractional pel ratio threshold is exceeded, wherein the field referencing pattern is kept the same when the half pel ratio is lower than a half pel ratio threshold and the fractional pel ratio is lower than a fractional pel ratio threshold, wherein the half pel ratio threshold is within a threshold tolerance of 0.5 and the fractional pel ratio threshold is within a threshold tolerance of 0.9, wherein the exception protocol determines that the field referencing pattern is a most recently coded reference field when the target field is a bottom field of an intra coded frame, wherein the exception protocol determines that the field referencing pattern is a most recently coded reference field when the target field is a bottom field of a P-frame in a sequence comprised of one or more B frames, and wherein the alternate half pel ratio threshold is within a threshold tolerance of 0.3 and the alternate fractional pel ratio threshold is within a threshold tolerance 0.7.