/* motion.c, motion vector decoding */ /* 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 #include "config.h" #include "global.h" /* private prototypes */ static void decode_motion_vector _ANSI_ARGS_( (int *pred, int r_size, int motion_code, int motion_residualesidual, int full_pel_vector)); /* ISO/IEC 13818-2 sections 6.2.5.2, 6.3.17.2, and 7.6.3: Motion vectors */ void motion_vectors(PMV, dmvector, motion_vertical_field_select, s, motion_vector_count, mv_format, h_r_size, v_r_size, dmv, mvscale) int PMV[2][2][2]; int dmvector[2]; int motion_vertical_field_select[2][2]; int s, motion_vector_count, mv_format, h_r_size, v_r_size, dmv, mvscale; { if (motion_vector_count == 1) { if (mv_format == MV_FIELD && !dmv) { motion_vertical_field_select[1][s] = motion_vertical_field_select[0][s] = Get_Bits(1); #ifdef TRACE if (Trace_Flag) { printf("motion_vertical_field_select[][%d] (%d): %d\n", s, motion_vertical_field_select[0][s], motion_vertical_field_select[0][s]); } #endif /* TRACE */ } motion_vector(PMV[0][s], dmvector, h_r_size, v_r_size, dmv, mvscale, 0); /* update other motion vector predictors */ PMV[1][s][0] = PMV[0][s][0]; PMV[1][s][1] = PMV[0][s][1]; } else { motion_vertical_field_select[0][s] = Get_Bits(1); #ifdef TRACE if (Trace_Flag) { printf("motion_vertical_field_select[0][%d] (%d): %d\n", s, motion_vertical_field_select[0][s], motion_vertical_field_select[0][s]); } #endif /* TRACE */ motion_vector(PMV[0][s], dmvector, h_r_size, v_r_size, dmv, mvscale, 0); motion_vertical_field_select[1][s] = Get_Bits(1); #ifdef TRACE if (Trace_Flag) { printf("motion_vertical_field_select[1][%d] (%d): %d\n", s, motion_vertical_field_select[1][s], motion_vertical_field_select[1][s]); } #endif /* TRACE */ motion_vector(PMV[1][s], dmvector, h_r_size, v_r_size, dmv, mvscale, 0); } } /* get and decode motion vector and differential motion vector for one prediction */ void motion_vector(PMV, dmvector, h_r_size, v_r_size, dmv, mvscale, full_pel_vector) int *PMV; int *dmvector; int h_r_size; int v_r_size; int dmv; /* MPEG-2 only: get differential motion vectors */ int mvscale; /* MPEG-2 only: field vector in frame pic */ int full_pel_vector; /* MPEG-1 only */ { int motion_code, motion_residual; /* horizontal component */ /* ISO/IEC 13818-2 Table B-10 */ motion_code = Get_motion_code(); motion_residual = (h_r_size != 0 && motion_code != 0) ? Get_Bits(h_r_size) : 0; #ifdef TRACE if (Trace_Flag) { if (h_r_size != 0 && motion_code != 0) { printf("motion_residual ("); Print_Bits(motion_residual, h_r_size, h_r_size); printf("): %d\n", motion_residual); } } #endif /* TRACE */ decode_motion_vector(&PMV[0], h_r_size, motion_code, motion_residual, full_pel_vector); if (dmv) dmvector[0] = Get_dmvector(); /* vertical component */ motion_code = Get_motion_code(); motion_residual = (v_r_size != 0 && motion_code != 0) ? Get_Bits(v_r_size) : 0; #ifdef TRACE if (Trace_Flag) { if (v_r_size != 0 && motion_code != 0) { printf("motion_residual ("); Print_Bits(motion_residual, v_r_size, v_r_size); printf("): %d\n", motion_residual); } } #endif /* TRACE */ if (mvscale) PMV[1] >>= 1; /* DIV 2 */ decode_motion_vector(&PMV[1], v_r_size, motion_code, motion_residual, full_pel_vector); if (mvscale) PMV[1] <<= 1; if (dmv) dmvector[1] = Get_dmvector(); #ifdef TRACE if (Trace_Flag) printf("PMV = %d,%d\n", PMV[0], PMV[1]); #endif /* TRACE */ } /* calculate motion vector component */ /* ISO/IEC 13818-2 section 7.6.3.1: Decoding the motion vectors */ /* Note: the arithmetic here is more elegant than that which is shown in 7.6.3.1. The end results (PMV[][][]) should, however, be the same. */ static void decode_motion_vector(pred, r_size, motion_code, motion_residual, full_pel_vector) int *pred; int r_size, motion_code, motion_residual; int full_pel_vector; /* MPEG-1 (ISO/IEC 11172-1) support */ { int lim, vec; lim = 16 << r_size; vec = full_pel_vector ? (*pred >> 1) : (*pred); if (motion_code > 0) { vec += ((motion_code - 1) << r_size) + motion_residual + 1; if (vec >= lim) vec -= lim + lim; } else if (motion_code < 0) { vec -= ((-motion_code - 1) << r_size) + motion_residual + 1; if (vec < -lim) vec += lim + lim; } *pred = full_pel_vector ? (vec << 1) : vec; } /* ISO/IEC 13818-2 section 7.6.3.6: Dual prime additional arithmetic */ void Dual_Prime_Arithmetic(DMV, dmvector, mvx, mvy) int DMV[][2]; int *dmvector; /* differential motion vector */ int mvx, mvy; /* decoded mv components (always in field format) */ { if (picture_structure == FRAME_PICTURE) { if (top_field_first) { /* vector for prediction of top field from bottom field */ DMV[0][0] = ((mvx + (mvx > 0)) >> 1) + dmvector[0]; DMV[0][1] = ((mvy + (mvy > 0)) >> 1) + dmvector[1] - 1; /* vector for prediction of bottom field from top field */ DMV[1][0] = ((3 * mvx + (mvx > 0)) >> 1) + dmvector[0]; DMV[1][1] = ((3 * mvy + (mvy > 0)) >> 1) + dmvector[1] + 1; } else { /* vector for prediction of top field from bottom field */ DMV[0][0] = ((3 * mvx + (mvx > 0)) >> 1) + dmvector[0]; DMV[0][1] = ((3 * mvy + (mvy > 0)) >> 1) + dmvector[1] - 1; /* vector for prediction of bottom field from top field */ DMV[1][0] = ((mvx + (mvx > 0)) >> 1) + dmvector[0]; DMV[1][1] = ((mvy + (mvy > 0)) >> 1) + dmvector[1] + 1; } } else { /* vector for prediction from field of opposite 'parity' */ DMV[0][0] = ((mvx + (mvx > 0)) >> 1) + dmvector[0]; DMV[0][1] = ((mvy + (mvy > 0)) >> 1) + dmvector[1]; /* correct for vertical field shift */ if (picture_structure == TOP_FIELD) DMV[0][1]--; else DMV[0][1]++; } }