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/*
* 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 */
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