From efb6836fe319d7bdf0d513f08bcf5abbe09c74b0 Mon Sep 17 00:00:00 2001 From: Ivan Kalvachev Date: Wed, 11 Jul 2007 22:01:21 +0000 Subject: [PATCH] Inport the original intiger IDCT from MPEG2 reference decoder. It passes IEEE1180 requirements. Originally committed as revision 9601 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/mpegidct.c | 211 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 211 insertions(+) create mode 100644 libavcodec/mpegidct.c diff --git a/libavcodec/mpegidct.c b/libavcodec/mpegidct.c new file mode 100644 index 0000000000..6f31045759 --- /dev/null +++ b/libavcodec/mpegidct.c @@ -0,0 +1,211 @@ +/* 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. + * + */ + +/**********************************************************/ +/* 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 "config.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 Initialize_Fast_IDCT _ANSI_ARGS_((void)); +void Fast_IDCT _ANSI_ARGS_((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]; +} + +/* two dimensional inverse discrete cosine transform */ +void Fast_IDCT(block) +short *block; +{ + int i; + + for (i=0; i<8; i++) + idctrow(block+8*i); + + for (i=0; i<8; i++) + idctcol(block+i); +} + +void Initialize_Fast_IDCT() +{ + int i; + + iclp = iclip+512; + for (i= -512; i<512; i++) + iclp[i] = (i<-256) ? -256 : ((i>255) ? 255 : i); +}