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libavcodec/eaidct.c

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00001 /*
00002  * Electronic Arts TGQ/TQI/MAD IDCT algorithm
00003  * Copyright (c) 2007-2008 Peter Ross <pross@xvid.org>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00028 #include "dsputil.h"
00029 
00030 #define ASQRT 181 /* (1/sqrt(2))<<8 */
00031 #define A4    669 /* cos(pi/8)*sqrt(2)<<9 */
00032 #define A2    277 /* sin(pi/8)*sqrt(2)<<9 */
00033 #define A5    196 /* sin(pi/8)<<9 */
00034 
00035 #define IDCT_TRANSFORM(dest,s0,s1,s2,s3,s4,s5,s6,s7,d0,d1,d2,d3,d4,d5,d6,d7,munge,src) {\
00036     const int a1 = (src)[s1] + (src)[s7]; \
00037     const int a7 = (src)[s1] - (src)[s7]; \
00038     const int a5 = (src)[s5] + (src)[s3]; \
00039     const int a3 = (src)[s5] - (src)[s3]; \
00040     const int a2 = (src)[s2] + (src)[s6]; \
00041     const int a6 = (ASQRT*((src)[s2] - (src)[s6]))>>8; \
00042     const int a0 = (src)[s0] + (src)[s4]; \
00043     const int a4 = (src)[s0] - (src)[s4]; \
00044     const int b0 = (((A4-A5)*a7 - A5*a3)>>9) + a1+a5; \
00045     const int b1 = (((A4-A5)*a7 - A5*a3)>>9) + ((ASQRT*(a1-a5))>>8); \
00046     const int b2 = (((A2+A5)*a3 + A5*a7)>>9) + ((ASQRT*(a1-a5))>>8); \
00047     const int b3 =  ((A2+A5)*a3 + A5*a7)>>9; \
00048     (dest)[d0] = munge(a0+a2+a6+b0); \
00049     (dest)[d1] = munge(a4+a6   +b1); \
00050     (dest)[d2] = munge(a4-a6   +b2); \
00051     (dest)[d3] = munge(a0-a2-a6+b3); \
00052     (dest)[d4] = munge(a0-a2-a6-b3); \
00053     (dest)[d5] = munge(a4-a6   -b2); \
00054     (dest)[d6] = munge(a4+a6   -b1); \
00055     (dest)[d7] = munge(a0+a2+a6-b0); \
00056 }
00057 /* end IDCT_TRANSFORM macro */
00058 
00059 #define MUNGE_NONE(x) (x)
00060 #define IDCT_COL(dest,src) IDCT_TRANSFORM(dest,0,8,16,24,32,40,48,56,0,8,16,24,32,40,48,56,MUNGE_NONE,src)
00061 
00062 #define MUNGE_8BIT(x) av_clip_uint8((x)>>4)
00063 #define IDCT_ROW(dest,src) IDCT_TRANSFORM(dest,0,1,2,3,4,5,6,7,0,1,2,3,4,5,6,7,MUNGE_8BIT,src)
00064 
00065 static inline void ea_idct_col(DCTELEM *dest, const DCTELEM *src) {
00066     if ((src[8]|src[16]|src[24]|src[32]|src[40]|src[48]|src[56])==0) {
00067         dest[0]  =
00068         dest[8]  =
00069         dest[16] =
00070         dest[24] =
00071         dest[32] =
00072         dest[40] =
00073         dest[48] =
00074         dest[56] = src[0];
00075     }else
00076         IDCT_COL(dest, src);
00077 }
00078 
00079 void ff_ea_idct_put_c(uint8_t *dest, int linesize, DCTELEM *block) {
00080     int i;
00081     DCTELEM temp[64];
00082     block[0] += 4;
00083     for (i=0; i<8; i++)
00084         ea_idct_col(&temp[i], &block[i]);
00085     for (i=0; i<8; i++)
00086         IDCT_ROW( (&dest[i*linesize]), (&temp[8*i]) );
00087 }

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