/* 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 <stdio.h>
#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]++;
}
}