GetDiff16x16B

Evaluate bi-predicted 16X16 block

Supported Technologies

SSE2

Synopsis

FwStatus   fwiGetDiff16x16B_8u16s_C1 ( const Fw8u * pSrcCurFw32s srcCurStepconst Fw8u * pSrcRefFFw32s srcRefStepFFw32s mcTypeFconst Fw8u * pSrcRefBFw32s srcRefStepBFw32s mcTypeBFw16s * pDstDiffFw32s dstDiffStepFw32s roundControl );

Parameters

dstDiffStep   Destination block step size (width of the block in bytes).
mcTypeB   Specifies the type of prediction used for backward frame motion compensation.
mcTypeF   Specifies the type of prediction used for forward frame motion compensation.
pDstDiff   Pointer to a 16X16 block in the destination plane which contains differences between current and reference blocks.
pSrcCur   Pointer to a block in the current plane.
pSrcRefB   Pointer to a backward block in the reference plane.
pSrcRefF   Pointer to a forward block in the reference plane.
roundControl   Specifies the type of rounding used for half-pixel approximation.
srcCurStep   Source current block step size (width of the block in bytes)
srcRefStepB   Source backward reference block step size (width of the block in bytes)
srcRefStepF   Source forward reference block step size (width of the block in bytes)

Description

This function compares a 16X16 source block to two 16X16 reference blocks and writes results to a difference block and a predictor block in a destination plane. The results are used to reduce error when subsequent blocks that refer to the source block are encoded.

Prediction is the mean of a forward prediction and a backward prediction based on the values in two reference blocks, using a compensation type specified by the mcType parameter.

When mcType = FWVC_MC_APX_FF, the reference block is used as the predictor block.

When mcType = FWVC_MC_APX_FH or FWVC_MC_APX_HF, each element of the predictor block is the average of two reference block elements.

When mcType = FWVC_MC_APX_HH, each element of the predictor block is the average of four reference block elements.

Encoding has half-pixel accuracy, and a rounding method must be specified.