/* idct.c, inverse fast discrete cosine transform */ /* 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. * * MPEG2AVI * -------- * v0.16B33 renamed the initialization function to init_idct_int32() * v0.16B32 removed the unused idct_row() and idct_col() functions * v0.16B3 changed var declarations to static, to enforce data align * v0.16B22 idct_FAST() renamed to idct_int32() * also merged idct_FAST() into a single function, to help VC++ * optimize it. * * v0.14 changed int to long, to avoid confusion when compiling on x86 * platform ( in VC++ "int" -> 32bits ) */ /**********************************************************/ /* inverse two dimensional DCT, Chen-Wang algorithm */ /* (cf. IEEE ASSP-32, pp. 803-816, Aug. 1984) */ /* 32-bit integer arithmetic (8 bit coefficients) */ /* 11 mults, 29 adds per DCT */ /* sE, 18.8.91 */ /**********************************************************/ /* coefficients extended to 12 bit for IEEE1180-1990 */ /* compliance sE, 2.1.94 */ /**********************************************************/ /* this code assumes >> to be a two's-complement arithmetic */ /* right shift: (-2)>>1 == -1 , (-3)>>1 == -2 */ //#include #include "idct.h" #define W1 2841 /* 2048*sqrt(2)*cos(1*pi/16) */ #define W2 2676 /* 2048*sqrt(2)*cos(2*pi/16) */ #define W3 2408 /* 2048*sqrt(2)*cos(3*pi/16) */ #define W5 1609 /* 2048*sqrt(2)*cos(5*pi/16) */ #define W6 1108 /* 2048*sqrt(2)*cos(6*pi/16) */ #define W7 565 /* 2048*sqrt(2)*cos(7*pi/16) */ /* global declarations */ //void init_idct_int32 (void); //void idct_int32 (short *block); /* private data */ static short iclip[1024]; /* clipping table */ static short *iclp; /* private prototypes */ //static void idctrow _ANSI_ARGS_((short *blk)); //static void idctcol _ANSI_ARGS_((short *blk)); /* row (horizontal) IDCT * * 7 pi 1 * dst[k] = sum c[l] * src[l] * cos( -- * ( k + - ) * l ) * l=0 8 2 * * where: c[0] = 128 * c[1..7] = 128*sqrt(2) */ /* static void idctrow(blk) short *blk; { int X0, X1, X2, X3, X4, X5, X6, X7, X8; // shortcut if (!((X1 = blk[4]<<11) | (X2 = blk[6]) | (X3 = blk[2]) | (X4 = blk[1]) | (X5 = blk[7]) | (X6 = blk[5]) | (X7 = blk[3]))) { blk[0]=blk[1]=blk[2]=blk[3]=blk[4]=blk[5]=blk[6]=blk[7]=blk[0]<<3; return; } X0 = (blk[0]<<11) + 128; // for proper rounding in the fourth stage // first stage X8 = W7*(X4+X5); X4 = X8 + (W1-W7)*X4; X5 = X8 - (W1+W7)*X5; X8 = W3*(X6+X7); X6 = X8 - (W3-W5)*X6; X7 = X8 - (W3+W5)*X7; // second stage X8 = X0 + X1; X0 -= X1; X1 = W6*(X3+X2); X2 = X1 - (W2+W6)*X2; X3 = X1 + (W2-W6)*X3; X1 = X4 + X6; X4 -= X6; X6 = X5 + X7; X5 -= X7; // third stage X7 = X8 + X3; X8 -= X3; X3 = X0 + X2; X0 -= X2; X2 = (181*(X4+X5)+128)>>8; X4 = (181*(X4-X5)+128)>>8; // fourth stage blk[0] = (X7+X1)>>8; blk[1] = (X3+X2)>>8; blk[2] = (X0+X4)>>8; blk[3] = (X8+X6)>>8; blk[4] = (X8-X6)>>8; blk[5] = (X0-X4)>>8; blk[6] = (X3-X2)>>8; blk[7] = (X7-X1)>>8; }*/ /* column (vertical) IDCT * * 7 pi 1 * dst[8*k] = sum c[l] * src[8*l] * cos( -- * ( k + - ) * l ) * l=0 8 2 * * where: c[0] = 1/1024 * c[1..7] = (1/1024)*sqrt(2) */ /* static void idctcol(blk) short *blk; { int X0, X1, X2, X3, X4, X5, X6, X7, X8; // shortcut if (!((X1 = (blk[8*4]<<8)) | (X2 = blk[8*6]) | (X3 = blk[8*2]) | (X4 = blk[8*1]) | (X5 = blk[8*7]) | (X6 = blk[8*5]) | (X7 = blk[8*3]))) { blk[8*0]=blk[8*1]=blk[8*2]=blk[8*3]=blk[8*4]=blk[8*5]=blk[8*6]=blk[8*7]= iclp[(blk[8*0]+32)>>6]; return; } X0 = (blk[8*0]<<8) + 8192; // first stage X8 = W7*(X4+X5) + 4; X4 = (X8+(W1-W7)*X4)>>3; X5 = (X8-(W1+W7)*X5)>>3; X8 = W3*(X6+X7) + 4; X6 = (X8-(W3-W5)*X6)>>3; X7 = (X8-(W3+W5)*X7)>>3; // second stage X8 = X0 + X1; X0 -= X1; X1 = W6*(X3+X2) + 4; X2 = (X1-(W2+W6)*X2)>>3; X3 = (X1+(W2-W6)*X3)>>3; X1 = X4 + X6; X4 -= X6; X6 = X5 + X7; X5 -= X7; // third stage X7 = X8 + X3; X8 -= X3; X3 = X0 + X2; X0 -= X2; X2 = (181*(X4+X5)+128)>>8; X4 = (181*(X4-X5)+128)>>8; // fourth stage blk[8*0] = iclp[(X7+X1)>>14]; blk[8*1] = iclp[(X3+X2)>>14]; blk[8*2] = iclp[(X0+X4)>>14]; blk[8*3] = iclp[(X8+X6)>>14]; blk[8*4] = iclp[(X8-X6)>>14]; blk[8*5] = iclp[(X0-X4)>>14]; blk[8*6] = iclp[(X3-X2)>>14]; blk[8*7] = iclp[(X7-X1)>>14]; }*/ // function pointer idctFuncPtr idct; /* two dimensional inverse discrete cosine transform */ //void j_rev_dct(block) //short *block; void idct_int32(short *const block) { // idct_int32_init() must be called before the first call to this function! /*int i; long i; for (i=0; i<8; i++) idctrow(block+8*i); for (i=0; i<8; i++) idctcol(block+i); */ static short *blk; static long i; static long X0, X1, X2, X3, X4, X5, X6, X7, X8; for (i = 0; i < 8; i++) // idct rows { blk = block + (i << 3); if (! ((X1 = blk[4] << 11) | (X2 = blk[6]) | (X3 = blk[2]) | (X4 = blk[1]) | (X5 = blk[7]) | (X6 = blk[5]) | (X7 = blk[3]))) { blk[0] = blk[1] = blk[2] = blk[3] = blk[4] = blk[5] = blk[6] = blk[7] = blk[0] << 3; continue; } X0 = (blk[0] << 11) + 128; // for proper rounding in the fourth stage // first stage X8 = W7 * (X4 + X5); X4 = X8 + (W1 - W7) * X4; X5 = X8 - (W1 + W7) * X5; X8 = W3 * (X6 + X7); X6 = X8 - (W3 - W5) * X6; X7 = X8 - (W3 + W5) * X7; // second stage X8 = X0 + X1; X0 -= X1; X1 = W6 * (X3 + X2); X2 = X1 - (W2 + W6) * X2; X3 = X1 + (W2 - W6) * X3; X1 = X4 + X6; X4 -= X6; X6 = X5 + X7; X5 -= X7; // third stage X7 = X8 + X3; X8 -= X3; X3 = X0 + X2; X0 -= X2; X2 = (181 * (X4 + X5) + 128) >> 8; X4 = (181 * (X4 - X5) + 128) >> 8; // fourth stage blk[0] = (short) ((X7 + X1) >> 8); blk[1] = (short) ((X3 + X2) >> 8); blk[2] = (short) ((X0 + X4) >> 8); blk[3] = (short) ((X8 + X6) >> 8); blk[4] = (short) ((X8 - X6) >> 8); blk[5] = (short) ((X0 - X4) >> 8); blk[6] = (short) ((X3 - X2) >> 8); blk[7] = (short) ((X7 - X1) >> 8); } // end for ( i = 0; i < 8; ++i ) IDCT-rows for (i = 0; i < 8; i++) // idct columns { blk = block + i; // shortcut if (! ((X1 = (blk[8 * 4] << 8)) | (X2 = blk[8 * 6]) | (X3 = blk[8 * 2]) | (X4 = blk[8 * 1]) | (X5 = blk[8 * 7]) | (X6 = blk[8 * 5]) | (X7 = blk[8 * 3]))) { blk[8 * 0] = blk[8 * 1] = blk[8 * 2] = blk[8 * 3] = blk[8 * 4] = blk[8 * 5] = blk[8 * 6] = blk[8 * 7] = iclp[(blk[8 * 0] + 32) >> 6]; continue; } X0 = (blk[8 * 0] << 8) + 8192; // first stage X8 = W7 * (X4 + X5) + 4; X4 = (X8 + (W1 - W7) * X4) >> 3; X5 = (X8 - (W1 + W7) * X5) >> 3; X8 = W3 * (X6 + X7) + 4; X6 = (X8 - (W3 - W5) * X6) >> 3; X7 = (X8 - (W3 + W5) * X7) >> 3; // second stage X8 = X0 + X1; X0 -= X1; X1 = W6 * (X3 + X2) + 4; X2 = (X1 - (W2 + W6) * X2) >> 3; X3 = (X1 + (W2 - W6) * X3) >> 3; X1 = X4 + X6; X4 -= X6; X6 = X5 + X7; X5 -= X7; // third stage X7 = X8 + X3; X8 -= X3; X3 = X0 + X2; X0 -= X2; X2 = (181 * (X4 + X5) + 128) >> 8; X4 = (181 * (X4 - X5) + 128) >> 8; // fourth stage blk[8 * 0] = iclp[(X7 + X1) >> 14]; blk[8 * 1] = iclp[(X3 + X2) >> 14]; blk[8 * 2] = iclp[(X0 + X4) >> 14]; blk[8 * 3] = iclp[(X8 + X6) >> 14]; blk[8 * 4] = iclp[(X8 - X6) >> 14]; blk[8 * 5] = iclp[(X0 - X4) >> 14]; blk[8 * 6] = iclp[(X3 - X2) >> 14]; blk[8 * 7] = iclp[(X7 - X1) >> 14]; } } // end function idct_int32(block) //void //idct_int32_init() void idct_int32_init() { int i; iclp = iclip + 512; for (i = -512; i < 512; i++) iclp[i] = (i < -256) ? -256 : ((i > 255) ? 255 : i); }