ffmpeg/libavcodec/xvididct.c

   1 /*
   2  * Xvid MPEG-4 IDCT
   3  *
   4  * Copyright (C) 2006-2011 Xvid Solutions GmbH
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file
  25  * Walken IDCT
  26  * Alternative IDCT implementation for decoding compatibility.
  27  *
  28  * @author Skal
  29  * @note This C version is not the original IDCT, but a modified one that
  30  *       yields the same error profile as the MMX/MMXEXT/SSE2 versions.
  31  */
  32
  33 #include "config.h"
  34 #include "libavutil/attributes.h"
  35 #include "avcodec.h"
  36 #include "idctdsp.h"
  37 #include "xvididct.h"
  38
  39 #define ROW_SHIFT 11
  40 #define COL_SHIFT  6
  41
  42 // #define FIX(x)   (int)((x) * (1 << ROW_SHIFT))
  43 #define RND0 65536 // 1 << (COL_SHIFT + ROW_SHIFT - 1);
  44 #define RND1 3597  // FIX (1.75683487303);
  45 #define RND2 2260  // FIX (1.10355339059);
  46 #define RND3 1203  // FIX (0.587788325588);
  47 #define RND4 0
  48 #define RND5 120   // FIX (0.058658283817);
  49 #define RND6 512   // FIX (0.25);
  50 #define RND7 512   // FIX (0.25);
  51
  52 static const int TAB04[] = { 22725, 21407, 19266, 16384, 12873,  8867, 4520 };
  53 static const int TAB17[] = { 31521, 29692, 26722, 22725, 17855, 12299, 6270 };
  54 static const int TAB26[] = { 29692, 27969, 25172, 21407, 16819, 11585, 5906 };
  55 static const int TAB35[] = { 26722, 25172, 22654, 19266, 15137, 10426, 5315 };
  56
  57 static int idct_row(short *in, const int *const tab, int rnd)
  58 {
  59     const int c1 = tab[0];
  60     const int c2 = tab[1];
  61     const int c3 = tab[2];
  62     const int c4 = tab[3];
  63     const int c5 = tab[4];
  64     const int c6 = tab[5];
  65     const int c7 = tab[6];
  66
  67     const int right = in[5] | in[6] | in[7];
  68     const int left  = in[1] | in[2] | in[3];
  69     if (!(right | in[4])) {
  70         const int k = c4 * in[0] + rnd;
  71         if (left) {
  72             const int a0 = k + c2 * in[2];
  73             const int a1 = k + c6 * in[2];
  74             const int a2 = k - c6 * in[2];
  75             const int a3 = k - c2 * in[2];
  76
  77             const int b0 = c1 * in[1] + c3 * in[3];
  78             const int b1 = c3 * in[1] - c7 * in[3];
  79             const int b2 = c5 * in[1] - c1 * in[3];
  80             const int b3 = c7 * in[1] - c5 * in[3];
  81
  82             in[0] = (a0 + b0) >> ROW_SHIFT;
  83             in[1] = (a1 + b1) >> ROW_SHIFT;
  84             in[2] = (a2 + b2) >> ROW_SHIFT;
  85             in[3] = (a3 + b3) >> ROW_SHIFT;
  86             in[4] = (a3 - b3) >> ROW_SHIFT;
  87             in[5] = (a2 - b2) >> ROW_SHIFT;
  88             in[6] = (a1 - b1) >> ROW_SHIFT;
  89             in[7] = (a0 - b0) >> ROW_SHIFT;
  90         } else {
  91             const int a0 = k >> ROW_SHIFT;
  92             if (a0) {
  93                 in[0] =
  94                 in[1] =
  95                 in[2] =
  96                 in[3] =
  97                 in[4] =
  98                 in[5] =
  99                 in[6] =
 100                 in[7] = a0;
 101             } else
 102                 return 0;
 103         }
 104     } else if (!(left | right)) {
 105         const int a0 = (rnd + c4 * (in[0] + in[4])) >> ROW_SHIFT;
 106         const int a1 = (rnd + c4 * (in[0] - in[4])) >> ROW_SHIFT;
 107
 108         in[0] = a0;
 109         in[3] = a0;
 110         in[4] = a0;
 111         in[7] = a0;
 112         in[1] = a1;
 113         in[2] = a1;
 114         in[5] = a1;
 115         in[6] = a1;
 116     } else {
 117         const int k  = c4 * in[0] + rnd;
 118         const int a0 = k + c2 * in[2] + c4 * in[4] + c6 * in[6];
 119         const int a1 = k + c6 * in[2] - c4 * in[4] - c2 * in[6];
 120         const int a2 = k - c6 * in[2] - c4 * in[4] + c2 * in[6];
 121         const int a3 = k - c2 * in[2] + c4 * in[4] - c6 * in[6];
 122
 123         const int b0 = c1 * in[1] + c3 * in[3] + c5 * in[5] + c7 * in[7];
 124         const int b1 = c3 * in[1] - c7 * in[3] - c1 * in[5] - c5 * in[7];
 125         const int b2 = c5 * in[1] - c1 * in[3] + c7 * in[5] + c3 * in[7];
 126         const int b3 = c7 * in[1] - c5 * in[3] + c3 * in[5] - c1 * in[7];
 127
 128         in[0] = (a0 + b0) >> ROW_SHIFT;
 129         in[1] = (a1 + b1) >> ROW_SHIFT;
 130         in[2] = (a2 + b2) >> ROW_SHIFT;
 131         in[3] = (a3 + b3) >> ROW_SHIFT;
 132         in[4] = (a3 - b3) >> ROW_SHIFT;
 133         in[5] = (a2 - b2) >> ROW_SHIFT;
 134         in[6] = (a1 - b1) >> ROW_SHIFT;
 135         in[7] = (a0 - b0) >> ROW_SHIFT;
 136     }
 137     return 1;
 138 }
 139
 140 #define TAN1  0x32EC
 141 #define TAN2  0x6A0A
 142 #define TAN3  0xAB0E
 143 #define SQRT2 0x5A82
 144
 145 #define MULT(c, x, n)  (((c) * (x)) >> (n))
 146 // 12b version => #define MULT(c,x, n)  ((((c) >> 3) * (x)) >> ((n) - 3))
 147 // 12b zero-testing version:
 148
 149 #define BUTTERFLY(a, b, tmp)     \
 150     (tmp) = (a) + (b);           \
 151     (b)   = (a) - (b);           \
 152     (a)   = (tmp)
 153
 154 #define LOAD_BUTTERFLY(m1, m2, a, b, tmp, s)   \
 155     (m1) = (s)[(a)] + (s)[(b)];                \
 156     (m2) = (s)[(a)] - (s)[(b)]
 157
 158 static void idct_col_8(short *const in)
 159 {
 160     int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, spill;
 161
 162     // odd
 163
 164     mm4 = (int) in[7 * 8];
 165     mm5 = (int) in[5 * 8];
 166     mm6 = (int) in[3 * 8];
 167     mm7 = (int) in[1 * 8];
 168
 169     mm0 = MULT(TAN1, mm4, 16) + mm7;
 170     mm1 = MULT(TAN1, mm7, 16) - mm4;
 171     mm2 = MULT(TAN3, mm5, 16) + mm6;
 172     mm3 = MULT(TAN3, mm6, 16) - mm5;
 173
 174     mm7 = mm0 + mm2;
 175     mm4 = mm1 - mm3;
 176     mm0 = mm0 - mm2;
 177     mm1 = mm1 + mm3;
 178     mm6 = mm0 + mm1;
 179     mm5 = mm0 - mm1;
 180     mm5 = 2 * MULT(SQRT2, mm5, 16); // 2*sqrt2
 181     mm6 = 2 * MULT(SQRT2, mm6, 16); // Watch out: precision loss but done to match
 182                                     // the pmulhw used in MMX/MMXEXT/SSE2 versions
 183
 184     // even
 185
 186     mm1 = (int) in[2 * 8];
 187     mm2 = (int) in[6 * 8];
 188     mm3 = MULT(TAN2, mm2, 16) + mm1;
 189     mm2 = MULT(TAN2, mm1, 16) - mm2;
 190
 191     LOAD_BUTTERFLY(mm0, mm1, 0 * 8, 4 * 8, spill, in);
 192
 193     BUTTERFLY(mm0, mm3, spill);
 194     BUTTERFLY(mm0, mm7, spill);
 195     in[8 * 0] = (int16_t) (mm0 >> COL_SHIFT);
 196     in[8 * 7] = (int16_t) (mm7 >> COL_SHIFT);
 197     BUTTERFLY(mm3, mm4, mm0);
 198     in[8 * 3] = (int16_t) (mm3 >> COL_SHIFT);
 199     in[8 * 4] = (int16_t) (mm4 >> COL_SHIFT);
 200
 201     BUTTERFLY(mm1, mm2, mm0);
 202     BUTTERFLY(mm1, mm6, mm0);
 203     in[8 * 1] = (int16_t) (mm1 >> COL_SHIFT);
 204     in[8 * 6] = (int16_t) (mm6 >> COL_SHIFT);
 205     BUTTERFLY(mm2, mm5, mm0);
 206     in[8 * 2] = (int16_t) (mm2 >> COL_SHIFT);
 207     in[8 * 5] = (int16_t) (mm5 >> COL_SHIFT);
 208 }
 209
 210 static void idct_col_4(short *const in)
 211 {
 212     int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, spill;
 213
 214     // odd
 215
 216     mm0 = (int) in[1 * 8];
 217     mm2 = (int) in[3 * 8];
 218
 219     mm1 = MULT(TAN1, mm0, 16);
 220     mm3 = MULT(TAN3, mm2, 16);
 221
 222     mm7 = mm0 + mm2;
 223     mm4 = mm1 - mm3;
 224     mm0 = mm0 - mm2;
 225     mm1 = mm1 + mm3;
 226     mm6 = mm0 + mm1;
 227     mm5 = mm0 - mm1;
 228     mm6 = 2 * MULT(SQRT2, mm6, 16); // 2*sqrt2
 229     mm5 = 2 * MULT(SQRT2, mm5, 16);
 230
 231     // even
 232
 233     mm0 = mm1 = (int) in[0 * 8];
 234     mm3 = (int) in[2 * 8];
 235     mm2 = MULT(TAN2, mm3, 16);
 236
 237     BUTTERFLY(mm0, mm3, spill);
 238     BUTTERFLY(mm0, mm7, spill);
 239     in[8 * 0] = (int16_t) (mm0 >> COL_SHIFT);
 240     in[8 * 7] = (int16_t) (mm7 >> COL_SHIFT);
 241     BUTTERFLY(mm3, mm4, mm0);
 242     in[8 * 3] = (int16_t) (mm3 >> COL_SHIFT);
 243     in[8 * 4] = (int16_t) (mm4 >> COL_SHIFT);
 244
 245     BUTTERFLY(mm1, mm2, mm0);
 246     BUTTERFLY(mm1, mm6, mm0);
 247     in[8 * 1] = (int16_t) (mm1 >> COL_SHIFT);
 248     in[8 * 6] = (int16_t) (mm6 >> COL_SHIFT);
 249     BUTTERFLY(mm2, mm5, mm0);
 250     in[8 * 2] = (int16_t) (mm2 >> COL_SHIFT);
 251     in[8 * 5] = (int16_t) (mm5 >> COL_SHIFT);
 252 }
 253
 254 static void idct_col_3(short *const in)
 255 {
 256     int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, spill;
 257
 258     // odd
 259
 260     mm7 = (int) in[1 * 8];
 261     mm4 = MULT(TAN1, mm7, 16);
 262
 263     mm6 = mm7 + mm4;
 264     mm5 = mm7 - mm4;
 265     mm6 = 2 * MULT(SQRT2, mm6, 16); // 2*sqrt2
 266     mm5 = 2 * MULT(SQRT2, mm5, 16);
 267
 268     // even
 269
 270     mm0 = mm1 = (int) in[0 * 8];
 271     mm3 = (int) in[2 * 8];
 272     mm2 = MULT(TAN2, mm3, 16);
 273
 274     BUTTERFLY(mm0, mm3, spill);
 275     BUTTERFLY(mm0, mm7, spill);
 276     in[8 * 0] = (int16_t) (mm0 >> COL_SHIFT);
 277     in[8 * 7] = (int16_t) (mm7 >> COL_SHIFT);
 278     BUTTERFLY(mm3, mm4, mm0);
 279     in[8 * 3] = (int16_t) (mm3 >> COL_SHIFT);
 280     in[8 * 4] = (int16_t) (mm4 >> COL_SHIFT);
 281
 282     BUTTERFLY(mm1, mm2, mm0);
 283     BUTTERFLY(mm1, mm6, mm0);
 284     in[8 * 1] = (int16_t) (mm1 >> COL_SHIFT);
 285     in[8 * 6] = (int16_t) (mm6 >> COL_SHIFT);
 286     BUTTERFLY(mm2, mm5, mm0);
 287     in[8 * 2] = (int16_t) (mm2 >> COL_SHIFT);
 288     in[8 * 5] = (int16_t) (mm5 >> COL_SHIFT);
 289 }
 290
 291 void ff_xvid_idct(int16_t *const in)
 292 {
 293     int i, rows = 0x07;
 294
 295     idct_row(in + 0 * 8, TAB04, RND0);
 296     idct_row(in + 1 * 8, TAB17, RND1);
 297     idct_row(in + 2 * 8, TAB26, RND2);
 298     if (idct_row(in + 3 * 8, TAB35, RND3))
 299         rows |= 0x08;
 300     if (idct_row(in + 4 * 8, TAB04, RND4))
 301         rows |= 0x10;
 302     if (idct_row(in + 5 * 8, TAB35, RND5))
 303         rows |= 0x20;
 304     if (idct_row(in + 6 * 8, TAB26, RND6))
 305         rows |= 0x40;
 306     if (idct_row(in + 7 * 8, TAB17, RND7))
 307         rows |= 0x80;
 308
 309     if (rows & 0xF0) {
 310         for (i = 0; i < 8; i++)
 311             idct_col_8(in + i);
 312     } else if (rows & 0x08) {
 313         for (i = 0; i < 8; i++)
 314             idct_col_4(in + i);
 315     } else {
 316         for (i = 0; i < 8; i++)
 317             idct_col_3(in + i);
 318     }
 319 }
 320
 321 static void xvid_idct_put(uint8_t *dest, int line_size, int16_t *block)
 322 {
 323     ff_xvid_idct(block);
 324     ff_put_pixels_clamped(block, dest, line_size);
 325 }
 326
 327 static void xvid_idct_add(uint8_t *dest, int line_size, int16_t *block)
 328 {
 329     ff_xvid_idct(block);
 330     ff_add_pixels_clamped(block, dest, line_size);
 331 }
 332
 333 av_cold void ff_xvid_idct_init(IDCTDSPContext *c, AVCodecContext *avctx)
 334 {
 335     const unsigned high_bit_depth = avctx->bits_per_raw_sample > 8;
 336
 337     if (high_bit_depth || avctx->lowres ||
 338         !(avctx->idct_algo == FF_IDCT_AUTO ||
 339           avctx->idct_algo == FF_IDCT_XVID))
 340         return;
 341
 342     if (avctx->idct_algo == FF_IDCT_XVID) {
 343         c->idct_put  = xvid_idct_put;
 344         c->idct_add  = xvid_idct_add;
 345         c->idct      = ff_xvid_idct;
 346         c->perm_type = FF_IDCT_PERM_NONE;
 347     }
 348
 349     if (ARCH_X86)
 350         ff_xvid_idct_init_x86(c, avctx, high_bit_depth);
 351
 352     ff_init_scantable_permutation(c->idct_permutation, c->perm_type);
 353 }