/* * motionvector.c -- * * Procedures to compute motion vectors. * */ /* * Copyright (c) 1995 The Regents of the University of California. * All rights reserved. * * Permission to use, copy, modify, and distribute this software and its * documentation for any purpose, without fee, and without written agreement is * hereby granted, provided that the above copyright notice and the following * two paragraphs appear in all copies of this software. * * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. */ /* * Portions of this software Copyright (c) 1995 Brown University. * All rights reserved. * * Permission to use, copy, modify, and distribute this software and its * documentation for any purpose, without fee, and without written agreement * is hereby granted, provided that the above copyright notice and the * following two paragraphs appear in all copies of this software. * * IN NO EVENT SHALL BROWN UNIVERSITY BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF BROWN * UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * BROWN UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A * PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" * BASIS, AND BROWN UNIVERSITY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. */ #include "util.h" #include "video.h" #include "proto.h" /* Changes to make the code reentrant: deglobalize curVidStream Additional changes: none -lsh@cs.brown.edu (Loring Holden) */ /* *-------------------------------------------------------------- * * ComputeVector -- * * Computes motion vector given parameters previously parsed * and reconstructed. * * Results: * Reconstructed motion vector info is put into recon_* parameters * passed to this function. Also updated previous motion vector * information. * * Side effects: * None. * *-------------------------------------------------------------- */ #define ComputeVector(recon_right_ptr, recon_down_ptr, recon_right_prev, recon_down_prev, f, full_pel_vector, motion_h_code, motion_v_code, motion_h_r, motion_v_r) \ \ { \ int comp_h_r, comp_v_r; \ int right_little, right_big, down_little, down_big; \ int max, min, new_vector; \ \ /* The following procedure for the reconstruction of motion vectors \ is a direct and simple implementation of the instructions given \ in the mpeg December 1991 standard draft. \ */ \ \ if (f == 1 || motion_h_code == 0) \ comp_h_r = 0; \ else \ comp_h_r = f - 1 - motion_h_r; \ \ if (f == 1 || motion_v_code == 0) \ comp_v_r = 0; \ else \ comp_v_r = f - 1 - motion_v_r; \ \ right_little = motion_h_code * f; \ if (right_little == 0) \ right_big = 0; \ else { \ if (right_little > 0) { \ right_little = right_little - comp_h_r; \ right_big = right_little - 32 * f; \ } \ else { \ right_little = right_little + comp_h_r; \ right_big = right_little + 32 * f; \ } \ } \ \ down_little = motion_v_code * f; \ if (down_little == 0) \ down_big = 0; \ else { \ if (down_little > 0) { \ down_little = down_little - comp_v_r; \ down_big = down_little - 32 * f; \ } \ else { \ down_little = down_little + comp_v_r; \ down_big = down_little + 32 * f; \ } \ } \ \ max = 16 * f - 1; \ min = -16 * f; \ \ new_vector = recon_right_prev + right_little; \ \ if (new_vector <= max && new_vector >= min) \ *recon_right_ptr = recon_right_prev + right_little; \ /* just new_vector */ \ else \ *recon_right_ptr = recon_right_prev + right_big; \ recon_right_prev = *recon_right_ptr; \ if (full_pel_vector) \ *recon_right_ptr = *recon_right_ptr << 1; \ \ new_vector = recon_down_prev + down_little; \ if (new_vector <= max && new_vector >= min) \ *recon_down_ptr = recon_down_prev + down_little; \ /* just new_vector */ \ else \ *recon_down_ptr = recon_down_prev + down_big; \ recon_down_prev = *recon_down_ptr; \ if (full_pel_vector) \ *recon_down_ptr = *recon_down_ptr << 1; \ } /* *-------------------------------------------------------------- * * ComputeForwVector -- * * Computes forward motion vector by calling ComputeVector * with appropriate parameters. * * Results: * Reconstructed motion vector placed in recon_right_for_ptr and * recon_down_for_ptr. * * Side effects: * None. * *-------------------------------------------------------------- */ void ComputeForwVector( int* recon_right_for_ptr, int* recon_down_for_ptr, VidStream* the_stream ) { Pict *picture; Macroblock *mblock; picture = &(the_stream->picture); mblock = &(the_stream->mblock); ComputeVector(recon_right_for_ptr, recon_down_for_ptr, mblock->recon_right_for_prev, mblock->recon_down_for_prev, (int) picture->forw_f, picture->full_pel_forw_vector, mblock->motion_h_forw_code, mblock->motion_v_forw_code, mblock->motion_h_forw_r, mblock->motion_v_forw_r); } /* *-------------------------------------------------------------- * * ComputeBackVector -- * * Computes backward motion vector by calling ComputeVector * with appropriate parameters. * * Results: * Reconstructed motion vector placed in recon_right_back_ptr and * recon_down_back_ptr. * * Side effects: * None. * *-------------------------------------------------------------- */ void ComputeBackVector( int* recon_right_back_ptr, int* recon_down_back_ptr, VidStream* the_stream ) { Pict *picture; Macroblock *mblock; picture = &(the_stream->picture); mblock = &(the_stream->mblock); ComputeVector(recon_right_back_ptr, recon_down_back_ptr, mblock->recon_right_back_prev, mblock->recon_down_back_prev, (int) picture->back_f, picture->full_pel_back_vector, mblock->motion_h_back_code, mblock->motion_v_back_code, mblock->motion_h_back_r, mblock->motion_v_back_r); } /* EOF */