libavcodec/eaidct.c

   1 /*
   2  * Electronic Arts TGQ/TQI/MAD IDCT algorithm
   3  * Copyright (c) 2007-2008 Peter Ross <pross@xvid.org>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file libavcodec/eaidct.c
  24  * Electronic Arts TGQ/TQI/MAD IDCT algorithm
  25  * @author Peter Ross <pross@xvid.org>
  26  */
  27
  28 #include "dsputil.h"
  29
  30 #define ASQRT 181 /* (1/sqrt(2))<<8 */
  31 #define A4    669 /* cos(pi/8)*sqrt(2)<<9 */
  32 #define A2    277 /* sin(pi/8)*sqrt(2)<<9 */
  33 #define A5    196 /* sin(pi/8)<<9 */
  34
  35 #define IDCT_TRANSFORM(dest,s0,s1,s2,s3,s4,s5,s6,s7,d0,d1,d2,d3,d4,d5,d6,d7,munge,src) {\
  36     const int a1 = (src)[s1] + (src)[s7]; \
  37     const int a7 = (src)[s1] - (src)[s7]; \
  38     const int a5 = (src)[s5] + (src)[s3]; \
  39     const int a3 = (src)[s5] - (src)[s3]; \
  40     const int a2 = (src)[s2] + (src)[s6]; \
  41     const int a6 = (ASQRT*((src)[s2] - (src)[s6]))>>8; \
  42     const int a0 = (src)[s0] + (src)[s4]; \
  43     const int a4 = (src)[s0] - (src)[s4]; \
  44     const int b0 = (((A4-A5)*a7 - A5*a3)>>9) + a1+a5; \
  45     const int b1 = (((A4-A5)*a7 - A5*a3)>>9) + ((ASQRT*(a1-a5))>>8); \
  46     const int b2 = (((A2+A5)*a3 + A5*a7)>>9) + ((ASQRT*(a1-a5))>>8); \
  47     const int b3 =  ((A2+A5)*a3 + A5*a7)>>9; \
  48     (dest)[d0] = munge(a0+a2+a6+b0); \
  49     (dest)[d1] = munge(a4+a6   +b1); \
  50     (dest)[d2] = munge(a4-a6   +b2); \
  51     (dest)[d3] = munge(a0-a2-a6+b3); \
  52     (dest)[d4] = munge(a0-a2-a6-b3); \
  53     (dest)[d5] = munge(a4-a6   -b2); \
  54     (dest)[d6] = munge(a4+a6   -b1); \
  55     (dest)[d7] = munge(a0+a2+a6-b0); \
  56 }
  57 /* end IDCT_TRANSFORM macro */
  58
  59 #define MUNGE_NONE(x) (x)
  60 #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)
  61
  62 #define MUNGE_8BIT(x) av_clip_uint8((x)>>4)
  63 #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)
  64
  65 static inline void ea_idct_col(DCTELEM *dest, const DCTELEM *src) {
  66     if ((src[8]|src[16]|src[24]|src[32]|src[40]|src[48]|src[56])==0) {
  67         dest[0]  =
  68         dest[8]  =
  69         dest[16] =
  70         dest[24] =
  71         dest[32] =
  72         dest[40] =
  73         dest[48] =
  74         dest[56] = src[0];
  75     }else
  76         IDCT_COL(dest, src);
  77 }
  78
  79 void ff_ea_idct_put_c(uint8_t *dest, int linesize, DCTELEM *block) {
  80     int i;
  81     DCTELEM temp[64];
  82     block[0] += 4;
  83     for (i=0; i<8; i++)
  84         ea_idct_col(&temp[i], &block[i]);
  85     for (i=0; i<8; i++)
  86         IDCT_ROW( (&dest[i*linesize]), (&temp[8*i]) );
  87 }