www.pudn.com > mpeg4_DECORE.rar > deblock_horiz_default_filter.c

/************************************************************************** 
 *                                                                        * 
 * This code has been developed by John Funnell. 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                        * 
 *                                                                        * 
 **************************************************************************/ 
/** 
*  Copyright (C) 2001 - Project Mayo 
 * 
 * John Funnell 
 * 
 * DivX Advanced Research Center  
* 
**/ 
 
/*** 
 
References:   
 * ISO/IEC 14496-2 
 * MoMuSys-FDIS-V1.0-990812 
 * Intel Architecture Software Developer's Manual 
   Volume 2: Instruction Set Reference 
 
***/ 
 
#include "postprocess_mmx.h" 
 
/* John Funnell, December 2000 */ 
 
 
/* horizontal deblocking filter used in default (non-DC) mode */ 
INLINE void deblock_horiz_default_filter(uint8_t *v, int stride, int QP) { 
	int a3_0, a3_1, a3_2, d; 
	int q1, q; 
	int y; 
 
	/*  
	   scalar implementation for the time being - going to MMX may be complex for  
		little gain? I have some ideas how do go to MMX but anyone's welcome to try!    
 
		The compiler used for this module can make a big difference to performance. 
		this seems to be fastest when compiled using pgcc.  I haven't tried the  
		latest Intel compiler yet. 
		 
		I suspect that the benefits from SIMD here are neglible since the scalar 
		version is easily able to break out of the loop and save CPU time.  SIMD 
		would have a lot more inertia and may have to complete all calculations 
		even if they are not needed.  Still, branches are expensive so, well 
		SIMD/MMX is worth a try! 
		 
		JF 
	*/ 
 
	for (y=0; y<4; y++) { 
 
		q1 = v[4] - v[5]; 
		q = q1 / 2; 
		if (q) { 
 
			a3_0  = q1; 
			a3_0 += a3_0 << 2; 
			a3_0 = 2*(v[3]-v[6]) - a3_0; 
			 
			/* apply the 'delta' function first and check there is a difference to avoid wasting time */ 
			if (ABS(a3_0) < 8*QP) { 
				a3_1  = v[3]-v[2]; 
				a3_2  = v[7]-v[8]; 
				a3_1 += a3_1 << 2; 
				a3_2 += a3_2 << 2; 
				a3_1 += (v[1]-v[4]) << 1; 
				a3_2 += (v[5]-v[8]) << 1; 
				d = ABS(a3_0) - MIN(ABS(a3_1), ABS(a3_2)); 
		 
				if (d > 0) { /* energy across boundary is greater than in one or both of the blocks */ 
					d += d<<2; 
					d = (d + 32) >> 6;  
	 
					if (d > 0) { 
	 
						//d *= SIGN(-a3_0); 
					 
						/* clip d in the range 0 ... q */ 
						if (q > 0) { 
							if (a3_0 < 0) { 
								//d = d<0 ? 0 : d; 
								d = d>q ? q : d; 
								v[4] -= d; 
								v[5] += d; 
							} 
						} else { 
							if (a3_0 > 0) { 
								//d = d>0 ? 0 : d; 
								d = (-d)