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/* Predict.c, motion compensation routines */
/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
/*
* Disclaimer of Warranty
*
* These software programs are available to the user without any license fee or
* royalty on an "as is" basis. The MPEG Software Simulation Group disclaims
* any and all warranties, whether express, implied, or statuary, including any
* implied warranties or merchantability or of fitness for a particular
* purpose. In no event shall the copyright-holder be liable for any
* incidental, punitive, or consequential damages of any kind whatsoever
* arising from the use of these programs.
*
* This disclaimer of warranty extends to the user of these programs and user's
* customers, employees, agents, transferees, successors, and assigns.
*
* The MPEG Software Simulation Group does not represent or warrant that the
* programs furnished hereunder are free of infringement of any third-party
* patents.
*
* Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
* are subject to royalty fees to patent holders. Many of these patents are
* general enough such that they are unavoidable regardless of implementation
* design.
*
*/
#include "config.h"
#include "global.h"
/* private prototypes */
static void form_prediction(unsigned char *src[], int sfield,
unsigned char *dst[], int dfield,
int lx, int lx2, int w, int h, int x, int y, int dx, int dy,
int average_flag);
static void form_component_prediction(unsigned char *src, unsigned char *dst,
int lx, int lx2, int w, int h, int x, int y, int dx, int dy, int average_flag);
void form_predictions(bx,by,macroblock_type,motion_type,PMV,motion_vertical_field_select,dmvector,stwtype)
int bx, by;
int macroblock_type;
int motion_type;
int PMV[2][2][2], motion_vertical_field_select[2][2], dmvector[2];
int stwtype;
{
int currentfield;
unsigned char **predframe;
int DMV[2][2];
int stwtop, stwbot;
stwtop = stwtype%3; /* 0:temporal, 1:(spat+temp)/2, 2:spatial */
stwbot = stwtype/3;
if ((macroblock_type & MACROBLOCK_MOTION_FORWARD)
|| (picture_coding_type==P_TYPE))
{
if (picture_structure==FRAME_PICTURE)
{
if ((motion_type==MC_FRAME)
|| !(macroblock_type & MACROBLOCK_MOTION_FORWARD))
{
/* frame-based prediction (broken into top and bottom halves
for spatial scalability prediction purposes) */
if (stwtop<2)
form_prediction(forward_reference_frame,0,current_frame,0,
Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,
PMV[0][0][0],PMV[0][0][1],stwtop);
if (stwbot<2)
form_prediction(forward_reference_frame,1,current_frame,1,
Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,
PMV[0][0][0],PMV[0][0][1],stwbot);
}
else if (motion_type==MC_FIELD) /* field-based prediction */
{
/* top field prediction */
if (stwtop<2)
form_prediction(forward_reference_frame,motion_vertical_field_select[0][0],
current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,stwtop);
/* bottom field prediction */
if (stwbot<2)
form_prediction(forward_reference_frame,motion_vertical_field_select[1][0],
current_frame,1,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by>>1,PMV[1][0][0],PMV[1][0][1]>>1,stwbot);
}
else if (motion_type==MC_DMV) /* dual prime prediction */
{
/* calculate derived motion vectors */
Dual_Prime_Arithmetic(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]>>1);
if (stwtop<2)
{
/* predict top field from top field */
form_prediction(forward_reference_frame,0,current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,
PMV[0][0][0],PMV[0][0][1]>>1,0);
/* predict and add to top field from bottom field */
form_prediction(forward_reference_frame,1,current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,
DMV[0][0],DMV[0][1],1);
}
if (stwbot<2)
{
/* predict bottom field from bottom field */
form_prediction(forward_reference_frame,1,current_frame,1,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,
PMV[0][0][0],PMV[0][0][1]>>1,0);
/* predict and add to bottom field from top field */
form_prediction(forward_reference_frame,0,current_frame,1,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,
DMV[1][0],DMV[1][1],1);
}
}
else
/* invalid motion_type */
cprintf("invalid motion_type\n");
}
else /* TOP_FIELD or BOTTOM_FIELD */
{
/* field picture */
currentfield = (picture_structure==BOTTOM_FIELD);
/* determine which frame to use for prediction */
if ((picture_coding_type==P_TYPE) && Second_Field
&& (currentfield!=motion_vertical_field_select[0][0]))
predframe = backward_reference_frame; /* same frame */
else
predframe = forward_reference_frame; /* previous frame */
if ((motion_type==MC_FIELD)
|| !(macroblock_type & MACROBLOCK_MOTION_FORWARD))
{
/* field-based prediction */
if (stwtop<2)
form_prediction(predframe,motion_vertical_field_select[0][0],current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,
PMV[0][0][0],PMV[0][0][1],stwtop);
}
else if (motion_type==MC_16X8)
{
if (stwtop<2)
{
form_prediction(predframe,motion_vertical_field_select[0][0],current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by,
PMV[0][0][0],PMV[0][0][1],stwtop);
/* determine which frame to use for lower half prediction */
if ((picture_coding_type==P_TYPE) && Second_Field
&& (currentfield!=motion_vertical_field_select[1][0]))
predframe = backward_reference_frame; /* same frame */
else
predframe = forward_reference_frame; /* previous frame */
form_prediction(predframe,motion_vertical_field_select[1][0],current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by+8,
PMV[1][0][0],PMV[1][0][1],stwtop);
}
}
else if (motion_type==MC_DMV) /* dual prime prediction */
{
if (Second_Field)
predframe = backward_reference_frame; /* same frame */
else
predframe = forward_reference_frame; /* previous frame */
/* calculate derived motion vectors */
Dual_Prime_Arithmetic(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]);
/* predict from field of same parity */
form_prediction(forward_reference_frame,currentfield,current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,
PMV[0][0][0],PMV[0][0][1],0);
/* predict from field of opposite parity */
form_prediction(predframe,!currentfield,current_frame,0,
Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,
DMV[0][0],DMV[0][1],1);
}
else
/* invalid motion_type */
cprintf("invalid motion_type\n");
}
stwtop = stwbot = 1;
}
if (macroblock_type & MACROBLOCK_MOTION_BACKWARD)
{
if (picture_structure==FRAME_PICTURE)
{
if (motion_type==MC_FRAME)
{
/* frame-based prediction */
if (stwtop<2)
form_prediction(backward_reference_frame,0,current_frame,0,
Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,
PMV[0][1][0],PMV[0][1][1],stwtop);
if (stwbot<2)
form_prediction(backward_reference_frame,1,current_frame,1,
Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,
PMV[0][1][0],PMV[0][1][1],stwbot);
}
else /* field-based prediction */
{
/* top field prediction */
if (stwtop<2)
form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],
current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by>>1,PMV[0][1][0],PMV[0][1][1]>>1,stwtop);
/* bottom field prediction */
if (stwbot<2)
form_prediction(backward_reference_frame,motion_vertical_field_select[1][1],
current_frame,1,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by>>1,PMV[1][1][0],PMV[1][1][1]>>1,stwbot);
}
}
else /* TOP_FIELD or BOTTOM_FIELD */
{
/* field picture */
if (motion_type==MC_FIELD)
{
/* field-based prediction */
form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],
current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,
bx,by,PMV[0][1][0],PMV[0][1][1],stwtop);
}
else if (motion_type==MC_16X8)
{
form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],
current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by,PMV[0][1][0],PMV[0][1][1],stwtop);
form_prediction(backward_reference_frame,motion_vertical_field_select[1][1],
current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,
bx,by+8,PMV[1][1][0],PMV[1][1][1],stwtop);
}
else
/* invalid motion_type */
cprintf("invalid motion_type\n");
}
}
}
static void form_prediction(src,sfield,dst,dfield,lx,lx2,w,h,x,y,dx,dy,average_flag)
unsigned char *src[]; /* prediction source buffer */
int sfield; /* prediction source field number (0 or 1) */
unsigned char *dst[]; /* prediction destination buffer */
int dfield; /* prediction destination field number (0 or 1)*/
int lx,lx2; /* line strides */
int w,h; /* prediction block/sub-block width, height */
int x,y; /* pixel co-ordinates of top-left sample in current MB */
int dx,dy; /* horizontal, vertical prediction address */
int average_flag; /* add prediction error to prediction ? */
{
/* Y */
form_component_prediction(src[0]+(sfield?lx2>>1:0),dst[0]+(dfield?lx2>>1:0),
lx,lx2,w,h,x,y,dx,dy,average_flag);
if (chroma_format!=CHROMA444)
{
lx>>=1; lx2>>=1; w>>=1; x>>=1; dx/=2;
}
if (chroma_format==CHROMA420)
{
h>>=1; y>>=1; dy/=2;
}
/* Cb */
form_component_prediction(src[1]+(sfield?lx2>>1:0),dst[1]+(dfield?lx2>>1:0),
lx,lx2,w,h,x,y,dx,dy,average_flag);
/* Cr */
form_component_prediction(src[2]+(sfield?lx2>>1:0),dst[2]+(dfield?lx2>>1:0),
lx,lx2,w,h,x,y,dx,dy,average_flag);
}
/* ISO/IEC 13818-2 section 7.6.4: Forming predictions */
/* NOTE: the arithmetic below produces numerically equivalent results
* to 7.6.4, yet is more elegant. It differs in the following ways:
*
* 1. the vectors (dx, dy) are based on cartesian frame
* coordiantes along a half-pel grid (always positive numbers)
* In contrast, vector[r][s][t] are differential (with positive and
* negative values). As a result, deriving the integer vectors
* (int_vec[t]) from dx, dy is accomplished by a simple right shift.
*
* 2. Half pel flags (xh, yh) are equivalent to the LSB (Least
* Significant Bit) of the half-pel coordinates (dx,dy).
*
*
* NOTE: the work of combining predictions (ISO/IEC 13818-2 section 7.6.7)
* is distributed among several other stages. This is accomplished by
* folding line offsets into the source and destination (src,dst)
* addresses (note the call arguments to form_prediction() in Predict()),
* line stride variables lx and lx2, the block dimension variables (w,h),
* average_flag, and by the very order in which Predict() is called.
* This implementation design (implicitly different than the spec)
* was chosen for its elegance.
*/
static void form_component_prediction(src,dst,lx,lx2,w,h,x,y,dx,dy,average_flag)
unsigned char *src;
unsigned char *dst;
int lx; /* raster line increment */
int lx2;
int w,h;
int x,y;
int dx,dy;
int average_flag; /* flag that signals bi-directional or Dual-Prime
averaging (7.6.7.1 and 7.6.7.4). if average_flag==1,
a previously formed prediction has been stored in
pel_pred[] */
{
int xint; /* horizontal integer sample vector: analogous to int_vec[0] */
int yint; /* vertical integer sample vectors: analogous to int_vec[1] */
int xh; /* horizontal half sample flag: analogous to half_flag[0] */
int yh; /* vertical half sample flag: analogous to half_flag[1] */
int i, j, v;
unsigned char *s; /* source pointer: analogous to pel_ref[][] */
unsigned char *d; /* destination pointer: analogous to pel_pred[][] */
/* half pel scaling for integer vectors */
xint = dx>>1;
yint = dy>>1;
/* derive half pel flags */
xh = dx & 1;
yh = dy & 1;
/* compute the linear address of pel_ref[][] and pel_pred[][]
based on cartesian/raster cordinates provided */
s = src + lx*(y+yint) + x + xint;
d = dst + lx*y + x;
if (!xh && !yh) /* no horizontal nor vertical half-pel */
{
if (average_flag)
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
v = d[i]+s[i];
d[i] = (v+(v>=0?1:0))>>1;
}
s+= lx2;
d+= lx2;
}
}
else
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
d[i] = s[i];
}
s+= lx2;
d+= lx2;
}
}
}
else if (!xh && yh) /* no horizontal but vertical half-pel */
{
if (average_flag)
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
v = d[i] + ((unsigned int)(s[i]+s[i+lx]+1)>>1);
d[i]=(v+(v>=0?1:0))>>1;
}
s+= lx2;
d+= lx2;
}
}
else
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
d[i] = (unsigned int)(s[i]+s[i+lx]+1)>>1;
}
s+= lx2;
d+= lx2;
}
}
}
else if (xh && !yh) /* horizontal but no vertical half-pel */
{
if (average_flag)
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
v = d[i] + ((unsigned int)(s[i]+s[i+1]+1)>>1);
d[i] = (v+(v>=0?1:0))>>1;
}
s+= lx2;
d+= lx2;
}
}
else
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
d[i] = (unsigned int)(s[i]+s[i+1]+1)>>1;
}
s+= lx2;
d+= lx2;
}
}
}
else /* if (xh && yh) horizontal and vertical half-pel */
{
if (average_flag)
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
v = d[i] + ((unsigned int)(s[i]+s[i+1]+s[i+lx]+s[i+lx+1]+2)>>2);
d[i] = (v+(v>=0?1:0))>>1;
}
s+= lx2;
d+= lx2;
}
}
else
{
for (j=0; j<h; j++)
{
for (i=0; i<w; i++)
{
d[i] = (unsigned int)(s[i]+s[i+1]+s[i+lx]+s[i+lx+1]+2)>>2;
}
s+= lx2;
d+= lx2;
}
}
}
}