/* 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 _ANSI_ARGS_((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 _ANSI_ARGS_((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 */ printf("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 */ printf("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 */ printf("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=0?1:0))>>1; } s+= lx2; d+= lx2; } } else { for (j=0; j>1); d[i]=(v+(v>=0?1:0))>>1; } s+= lx2; d+= lx2; } } else { for (j=0; j>1; } s+= lx2; d+= lx2; } } } else if (xh && !yh) /* horizontal but no vertical half-pel */ { if (average_flag) { for (j=0; j>1); d[i] = (v+(v>=0?1:0))>>1; } s+= lx2; d+= lx2; } } else { for (j=0; j>1; } s+= lx2; d+= lx2; } } } else /* if (xh && yh) horizontal and vertical half-pel */ { if (average_flag) { for (j=0; j>2); d[i] = (v+(v>=0?1:0))>>1; } s+= lx2; d+= lx2; } } else { for (j=0; j>2; } s+= lx2; d+= lx2; } } } }