mot_code.c

MPEG4编解码的C语言源代码

/**************************************************************************
 *                                                                        *
 * This code is developed by Adam Li.  This software is an                *
 * implementation of a part of one or more MPEG-4 Video tools as          *
 * specified in ISO/IEC 14496-2 standard.  Those intending to use this    *
 * software module in hardware or software products are advised that its  *
 * use may infringe existing patents or copyrights, and any such use      *
 * would be at such party's own risk.  The original developer of this     *
 * software module and his/her company, and subsequent editors and their  *
 * companies (including Project Mayo), will have no liability for use of  *
 * this software or modifications or derivatives thereof.                 *
 *                                                                        *
 * Project Mayo gives users of the Codec a license to this software       *
 * module or modifications thereof for use in hardware or software        *
 * products claiming conformance to the MPEG-4 Video Standard as          *
 * described in the Open DivX license.                                    *
 *                                                                        *
 * The complete Open DivX license can be found at                         *
 * http://www.projectmayo.com/opendivx/license.php .                      *
 *                                                                        *
 **************************************************************************/

/**************************************************************************
 *
 *  mot_code.c
 *
 *  Copyright (C) 2001  Project Mayo
 *
 *  Adam Li
 *
 *  DivX Advance Research Center <[e-mail]>
 *
 **************************************************************************/

/* This file contains some functions to code the motion data of the image.*/
/* Some codes of this project come from MoMuSys MPEG-4 implementation.    */
/* Please see seperate acknowledgement file for a list of contributors.   */

#include "vm_common_defs.h"
#include "bitstream.h"

#include "putvlc.h"

/* ------------------------------------------------------------------------- */

/* Specific macros (include references to internal vars. of the functions) */

/* 16x16 MV obtainment */
#define MBV_H(h,v)      (ph[2*(v)*2*hdim+2*(h)])
#define MBV_V(h,v)      (pv[2*(v)*2*hdim+2*(h)])

/* 8x8 MV obtainment */
#define BV_H(h,v,h2,v2) (ph[(2*(v)+(v2))*2*hdim+2*(h)+(h2)])
#define BV_V(h,v,h2,v2) (pv[(2*(v)+(v2))*2*hdim+2*(h)+(h2)])

/* MB mode obtainment */
#define MB_MODE(h,v)    ( ((h)<0||(h)>=hdim||(v)<0||(v)>=vdim ? MBM_OUT : (pm[(v)*hdim+(h)])) )

/* get 8x8 MV component */
#define BV(p,xdim,h,v,h2,v2) (p[(2*(v)+(v2))*(xdim)+2*(h)+(h2)])

/* ------------------------------------------------------------------------- */


/* declaration for functions in this file */
Int WriteMVcomponent(Int f_code, Int dmv, Image *bs);
Void ScaleMVD (Int f_code, Int diff_vector, Int *residual, Int *vlc_code_mag);
Void  	find_pmvs (Image *mot_x, Image *mot_y, Image *MB_decisions, Image *B_decisions,
	Int x, Int y, Int block, Int transparent_value, Int quarter_pel, Int *error_flag,
	Int *mvx, Int *mvy, Int newgob);
SInt ModeMB (Image *MB_decision, Int i, Int j);


/***********************************************************CommentBegin******
 *
 * -- Bits_CountMB_Motion --
 *
 * Purpose :
 *      Encodes the MV's Images acording to modes and alpha Images
 *      (see notes below). The codewords are appended to the bitstream.
 *      Included in text_code.h .
 *
 * Return values :
 *      Int     mv_bits   Returns the number of bits sent to the bitstream
 *
 * Description :
 *      1) No checking is made for the consistence of image sizes
 *      2) It assumes the output image has been previously allocated.
 *      3) Transparent MB's are not coded (no codeword is transmited).
 *      4) Motion vectors for 8x8 transparent blocks within
 *         non-totally-transparent MB's are transmitted as MV (0,0) (not MVD
 *         (0,0)). This is made in the  hope that this MV's are neither
 *         employed for block reconstruction nor for MV prediction.
 *
 ***********************************************************CommentEnd********/

Int
Bits_CountMB_Motion(
Image   *mot_h,									  /* <-- motion vectors (Float) - per block    */
Image   *mot_v,									  /* <-- motion vectors (Float) - per block    */
Image   *alpha,									  /* <-- macroblocks modes (SInt) - per block  */
Image   *modes,									  /* <-- macroblocks modes (SInt) - per MB     */
Int     h,										  /* <-- horizontal coordinate of the MB       */
Int     v,										  /* <-- vertical coordinate of the MB         */
Int     f_code,									  /* <-- MV range in 1/2 or 1/4 pel units 1=32,2=64,...,7=2048 */
												  /* <-- flag for quarter pel MC mode     */
Int     quarter_pel,       /* MW QPEL 07-JUL-1998 */
Image   *bs,									  /* --> output (SInt)                         */
Int     error_res_disable,
Int     after_marker,
Int     **slice_nb,
Int arbitrary_shape
)
{
	Int     vdim, hdim;							  /* Dimensions in macroblocks */
		Float   *ph, *pv;						  /* Motion vectors            */
		SInt    *pm;							  /* Modes                     */
		SInt    *pa;							  /* Alpha                     */
		Int     mode;
		Int     bits_mot = 0;

	/* From switch statement */
		Int     i, error_flag=0,mvx=0,mvy=0;
		Float   pred_h, pred_v;
		Float   diff_h, diff_v;
		Int     bh, bv;
		Int     local_f_code;					  /* MW QPEL 07-JUL-1998 */
		Float   subdim;							  /* MW QPEL 07-JUL-1998 */

		vdim = (Int)modes->y;
		hdim = (Int)modes->x;
		ph=(Float*)GetImageData(mot_h);
		pv=(Float*)GetImageData(mot_v);
		pm=(SInt*)GetImageData(modes);
		pa=NULL;//(SInt*)GetImageData(alpha);


	/* MW QPEL 07-JUL-1998 >> */
	/* Set local_f_code and subdim according to quarter_pel */
		if (quarter_pel)
	{
		local_f_code = f_code+1;
			subdim = 4.0;
	}
	else
	{
		local_f_code = f_code;
			subdim = 2.0;
	}
	/* << MW QPEL 07-JUL-1998 */

	switch (mode=MB_MODE(h,v))
	{
		case MBM_INTRA:
		break;

		case MBM_INTER16:
		/* Prediction obtainment */
		find_pmvs(mot_h,mot_v,modes,alpha,h,v,0,MBM_TRANSPARENT,
									  /* MW QPEL 07-JUL-1998 */
		quarter_pel,&error_flag,&mvx,&mvy,0);

		pred_h=((Float)mvx)/subdim;			  /* MW QPEL 07-JUL-1998 */
		pred_v=((Float)mvy)/subdim;		  /* MW QPEL 07-JUL-1998 */

										  /* MW QPEL 07-JUL-1998 */
		bits_mot += WriteMVcomponent(local_f_code, (Int)(subdim*(MBV_H(h,v) - pred_h)), bs);
										  /* MW QPEL 07-JUL-1998 */
		bits_mot += WriteMVcomponent(local_f_code, (Int)(subdim*(MBV_V(h,v) - pred_v)), bs);

		break;

		case MBM_INTER8:
		i=1;
		for (bv=0; bv<=1; bv++)
			for (bh=0; bh<=1; bh++)
		{
			find_pmvs(mot_h,mot_v,modes,alpha,h,v,i,MBM_TRANSPARENT,
								  /* MW QPEL 07-JUL-1998 */
			quarter_pel,&error_flag,&mvx,&mvy,0);

			pred_h=((Float)mvx)/subdim;		  /* MW QPEL 07-JUL-1998 */
			pred_v=((Float)mvy)/subdim;	  /* MW QPEL 07-JUL-1998 */

			i++;

			diff_h=BV_H(h,v,bh,bv)-pred_h;
			diff_v=BV_V(h,v,bh,bv)-pred_v;

									  /* MW QPEL 07-JUL-1998 */
			bits_mot += WriteMVcomponent(local_f_code, (Int)(subdim*diff_h), bs);
									  /* MW QPEL 07-JUL-1998 */
			bits_mot += WriteMVcomponent(local_f_code, (Int)(subdim*diff_v), bs);
		}
		break;
	}

	return bits_mot;
}


/***********************************************************CommentBegin******
 *
 * -- WriteMVcomponent -- Encodes a single motion vector component
 *
 * Purpose :
 *      Scales the motion vector difference, VLC the most significant part,
 *      then outputs the residual (least significant part) as a FLC.
 *
 * Arguments in :
 *      Int   f_code,         Range for MV, (1/2/3) => (32/64/128) 1/2 units
 *      Float diff_vector,    MV Diff. component (in 1/2 units (in field))
 *      Image bs              Bitstream output
 *
 * Return values :
 *      The number of bits for this encoding
 *
 * Side effects :
 *      The encoded motion vector is added to the bitstream
 *
 ***********************************************************CommentEnd********/

Int
WriteMVcomponent(
	Int     f_code,
	Int     dmv,
	Image   *bs
)
{
	Int   residual, vlc_code_mag, bits, entry;

		ScaleMVD(f_code, dmv, &residual, &vlc_code_mag);

		if (vlc_code_mag < 0)
		entry = vlc_code_mag + 65;
		else
		entry = vlc_code_mag;

		bits = PutMV (entry, bs);

		if ((f_code != 1) && (vlc_code_mag != 0))
	{
		BitstreamPutBits(bs, residual, f_code-1);
			bits += f_code - 1;
	}
	return(bits);
}


/***********************************************************CommentBegin******
 *
 * -- ScaleMVD -- Scales MVD component acording to the MV range
 *
 * Purpose :
 *      Scales a Motion Vector Difference (MVD) component (x or y) according
 *      to the MV range. The maximum range that can be represented is
 *      determined by the f_code encoded in the VOP header. Two values,
 *      vlc_code_mag and residual, are generated.
 *
 * Description :
 *      1) The range of the MV's is computed according to the f_code.
 *      2) The range of the MVD component is reduced to fall in the
 *         correct range.
 *      3) Two values are generated:
 *         vlc_code_mag: It will be VLC coded in other function.
 *         residual    : It will be FLC coded in other function.
 *
 ***********************************************************CommentEnd********/

Void
ScaleMVD (
	Int  f_code,									  /* <-- MV range in 1/2 units: 1=32,2=64,...,7=2048     */
	Int  diff_vector,								  /* <-- MV Difference commponent in 1/2 units           */
	Int  *residual,									  /* --> value to be FLC coded                           */
	Int  *vlc_code_mag								  /* --> value to be VLC coded                           */
)
{
	Int   range;
		Int   scale_factor;
		Int   r_size;
		Int   low;
		Int   high;
		Int   aux;

		r_size = f_code-1;
		scale_factor = 1<<r_size;
		range = 32*scale_factor;
		low   = -range;
		high  =  range-1;
		if (diff_vector < low)