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xvididct.c
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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 }
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