Commit | Line | Data |
---|---|---|
2ba45a60 DM |
1 | /* |
2 | * This file is part of the Independent JPEG Group's software. | |
3 | * | |
4 | * The authors make NO WARRANTY or representation, either express or implied, | |
5 | * with respect to this software, its quality, accuracy, merchantability, or | |
6 | * fitness for a particular purpose. This software is provided "AS IS", and | |
7 | * you, its user, assume the entire risk as to its quality and accuracy. | |
8 | * | |
9 | * This software is copyright (C) 1991-1996, Thomas G. Lane. | |
10 | * All Rights Reserved except as specified below. | |
11 | * | |
12 | * Permission is hereby granted to use, copy, modify, and distribute this | |
13 | * software (or portions thereof) for any purpose, without fee, subject to | |
14 | * these conditions: | |
15 | * (1) If any part of the source code for this software is distributed, then | |
16 | * this README file must be included, with this copyright and no-warranty | |
17 | * notice unaltered; and any additions, deletions, or changes to the original | |
18 | * files must be clearly indicated in accompanying documentation. | |
19 | * (2) If only executable code is distributed, then the accompanying | |
20 | * documentation must state that "this software is based in part on the work | |
21 | * of the Independent JPEG Group". | |
22 | * (3) Permission for use of this software is granted only if the user accepts | |
23 | * full responsibility for any undesirable consequences; the authors accept | |
24 | * NO LIABILITY for damages of any kind. | |
25 | * | |
26 | * These conditions apply to any software derived from or based on the IJG | |
27 | * code, not just to the unmodified library. If you use our work, you ought | |
28 | * to acknowledge us. | |
29 | * | |
30 | * Permission is NOT granted for the use of any IJG author's name or company | |
31 | * name in advertising or publicity relating to this software or products | |
32 | * derived from it. This software may be referred to only as "the Independent | |
33 | * JPEG Group's software". | |
34 | * | |
35 | * We specifically permit and encourage the use of this software as the basis | |
36 | * of commercial products, provided that all warranty or liability claims are | |
37 | * assumed by the product vendor. | |
38 | * | |
39 | * This file contains a slow-but-accurate integer implementation of the | |
40 | * forward DCT (Discrete Cosine Transform). | |
41 | * | |
42 | * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT | |
43 | * on each column. Direct algorithms are also available, but they are | |
44 | * much more complex and seem not to be any faster when reduced to code. | |
45 | * | |
46 | * This implementation is based on an algorithm described in | |
47 | * C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical Fast 1-D DCT | |
48 | * Algorithms with 11 Multiplications", Proc. Int'l. Conf. on Acoustics, | |
49 | * Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991. | |
50 | * The primary algorithm described there uses 11 multiplies and 29 adds. | |
51 | * We use their alternate method with 12 multiplies and 32 adds. | |
52 | * The advantage of this method is that no data path contains more than one | |
53 | * multiplication; this allows a very simple and accurate implementation in | |
54 | * scaled fixed-point arithmetic, with a minimal number of shifts. | |
55 | */ | |
56 | ||
57 | /** | |
58 | * @file | |
59 | * Independent JPEG Group's slow & accurate dct. | |
60 | */ | |
61 | ||
62 | #include "libavutil/common.h" | |
63 | #include "dct.h" | |
64 | ||
65 | #include "bit_depth_template.c" | |
66 | ||
67 | #define DCTSIZE 8 | |
68 | #define BITS_IN_JSAMPLE BIT_DEPTH | |
69 | #define GLOBAL(x) x | |
70 | #define RIGHT_SHIFT(x, n) ((x) >> (n)) | |
71 | #define MULTIPLY16C16(var,const) ((var)*(const)) | |
72 | ||
73 | #if 1 //def USE_ACCURATE_ROUNDING | |
74 | #define DESCALE(x,n) RIGHT_SHIFT((x) + (1 << ((n) - 1)), n) | |
75 | #else | |
76 | #define DESCALE(x,n) RIGHT_SHIFT(x, n) | |
77 | #endif | |
78 | ||
79 | ||
80 | /* | |
81 | * This module is specialized to the case DCTSIZE = 8. | |
82 | */ | |
83 | ||
84 | #if DCTSIZE != 8 | |
85 | #error "Sorry, this code only copes with 8x8 DCTs." | |
86 | #endif | |
87 | ||
88 | ||
89 | /* | |
90 | * The poop on this scaling stuff is as follows: | |
91 | * | |
92 | * Each 1-D DCT step produces outputs which are a factor of sqrt(N) | |
93 | * larger than the true DCT outputs. The final outputs are therefore | |
94 | * a factor of N larger than desired; since N=8 this can be cured by | |
95 | * a simple right shift at the end of the algorithm. The advantage of | |
96 | * this arrangement is that we save two multiplications per 1-D DCT, | |
97 | * because the y0 and y4 outputs need not be divided by sqrt(N). | |
98 | * In the IJG code, this factor of 8 is removed by the quantization step | |
99 | * (in jcdctmgr.c), NOT in this module. | |
100 | * | |
101 | * We have to do addition and subtraction of the integer inputs, which | |
102 | * is no problem, and multiplication by fractional constants, which is | |
103 | * a problem to do in integer arithmetic. We multiply all the constants | |
104 | * by CONST_SCALE and convert them to integer constants (thus retaining | |
105 | * CONST_BITS bits of precision in the constants). After doing a | |
106 | * multiplication we have to divide the product by CONST_SCALE, with proper | |
107 | * rounding, to produce the correct output. This division can be done | |
108 | * cheaply as a right shift of CONST_BITS bits. We postpone shifting | |
109 | * as long as possible so that partial sums can be added together with | |
110 | * full fractional precision. | |
111 | * | |
112 | * The outputs of the first pass are scaled up by PASS1_BITS bits so that | |
113 | * they are represented to better-than-integral precision. These outputs | |
114 | * require BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word | |
115 | * with the recommended scaling. (For 12-bit sample data, the intermediate | |
116 | * array is int32_t anyway.) | |
117 | * | |
118 | * To avoid overflow of the 32-bit intermediate results in pass 2, we must | |
119 | * have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <= 26. Error analysis | |
120 | * shows that the values given below are the most effective. | |
121 | */ | |
122 | ||
123 | #undef CONST_BITS | |
124 | #undef PASS1_BITS | |
125 | #undef OUT_SHIFT | |
126 | ||
127 | #if BITS_IN_JSAMPLE == 8 | |
128 | #define CONST_BITS 13 | |
129 | #define PASS1_BITS 4 /* set this to 2 if 16x16 multiplies are faster */ | |
130 | #define OUT_SHIFT PASS1_BITS | |
131 | #else | |
132 | #define CONST_BITS 13 | |
133 | #define PASS1_BITS 1 /* lose a little precision to avoid overflow */ | |
134 | #define OUT_SHIFT (PASS1_BITS + 1) | |
135 | #endif | |
136 | ||
137 | /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus | |
138 | * causing a lot of useless floating-point operations at run time. | |
139 | * To get around this we use the following pre-calculated constants. | |
140 | * If you change CONST_BITS you may want to add appropriate values. | |
141 | * (With a reasonable C compiler, you can just rely on the FIX() macro...) | |
142 | */ | |
143 | ||
144 | #if CONST_BITS == 13 | |
145 | #define FIX_0_298631336 ((int32_t) 2446) /* FIX(0.298631336) */ | |
146 | #define FIX_0_390180644 ((int32_t) 3196) /* FIX(0.390180644) */ | |
147 | #define FIX_0_541196100 ((int32_t) 4433) /* FIX(0.541196100) */ | |
148 | #define FIX_0_765366865 ((int32_t) 6270) /* FIX(0.765366865) */ | |
149 | #define FIX_0_899976223 ((int32_t) 7373) /* FIX(0.899976223) */ | |
150 | #define FIX_1_175875602 ((int32_t) 9633) /* FIX(1.175875602) */ | |
151 | #define FIX_1_501321110 ((int32_t) 12299) /* FIX(1.501321110) */ | |
152 | #define FIX_1_847759065 ((int32_t) 15137) /* FIX(1.847759065) */ | |
153 | #define FIX_1_961570560 ((int32_t) 16069) /* FIX(1.961570560) */ | |
154 | #define FIX_2_053119869 ((int32_t) 16819) /* FIX(2.053119869) */ | |
155 | #define FIX_2_562915447 ((int32_t) 20995) /* FIX(2.562915447) */ | |
156 | #define FIX_3_072711026 ((int32_t) 25172) /* FIX(3.072711026) */ | |
157 | #else | |
158 | #define FIX_0_298631336 FIX(0.298631336) | |
159 | #define FIX_0_390180644 FIX(0.390180644) | |
160 | #define FIX_0_541196100 FIX(0.541196100) | |
161 | #define FIX_0_765366865 FIX(0.765366865) | |
162 | #define FIX_0_899976223 FIX(0.899976223) | |
163 | #define FIX_1_175875602 FIX(1.175875602) | |
164 | #define FIX_1_501321110 FIX(1.501321110) | |
165 | #define FIX_1_847759065 FIX(1.847759065) | |
166 | #define FIX_1_961570560 FIX(1.961570560) | |
167 | #define FIX_2_053119869 FIX(2.053119869) | |
168 | #define FIX_2_562915447 FIX(2.562915447) | |
169 | #define FIX_3_072711026 FIX(3.072711026) | |
170 | #endif | |
171 | ||
172 | ||
173 | /* Multiply an int32_t variable by an int32_t constant to yield an int32_t result. | |
174 | * For 8-bit samples with the recommended scaling, all the variable | |
175 | * and constant values involved are no more than 16 bits wide, so a | |
176 | * 16x16->32 bit multiply can be used instead of a full 32x32 multiply. | |
177 | * For 12-bit samples, a full 32-bit multiplication will be needed. | |
178 | */ | |
179 | ||
180 | #if BITS_IN_JSAMPLE == 8 && CONST_BITS<=13 && PASS1_BITS<=2 | |
181 | #define MULTIPLY(var,const) MULTIPLY16C16(var,const) | |
182 | #else | |
183 | #define MULTIPLY(var,const) ((var) * (const)) | |
184 | #endif | |
185 | ||
186 | ||
187 | static av_always_inline void FUNC(row_fdct)(int16_t *data) | |
188 | { | |
189 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |
190 | int tmp10, tmp11, tmp12, tmp13; | |
191 | int z1, z2, z3, z4, z5; | |
192 | int16_t *dataptr; | |
193 | int ctr; | |
194 | ||
195 | /* Pass 1: process rows. */ | |
196 | /* Note results are scaled up by sqrt(8) compared to a true DCT; */ | |
197 | /* furthermore, we scale the results by 2**PASS1_BITS. */ | |
198 | ||
199 | dataptr = data; | |
200 | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |
201 | tmp0 = dataptr[0] + dataptr[7]; | |
202 | tmp7 = dataptr[0] - dataptr[7]; | |
203 | tmp1 = dataptr[1] + dataptr[6]; | |
204 | tmp6 = dataptr[1] - dataptr[6]; | |
205 | tmp2 = dataptr[2] + dataptr[5]; | |
206 | tmp5 = dataptr[2] - dataptr[5]; | |
207 | tmp3 = dataptr[3] + dataptr[4]; | |
208 | tmp4 = dataptr[3] - dataptr[4]; | |
209 | ||
210 | /* Even part per LL&M figure 1 --- note that published figure is faulty; | |
211 | * rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | |
212 | */ | |
213 | ||
214 | tmp10 = tmp0 + tmp3; | |
215 | tmp13 = tmp0 - tmp3; | |
216 | tmp11 = tmp1 + tmp2; | |
217 | tmp12 = tmp1 - tmp2; | |
218 | ||
219 | dataptr[0] = (int16_t) ((tmp10 + tmp11) * (1 << PASS1_BITS)); | |
220 | dataptr[4] = (int16_t) ((tmp10 - tmp11) * (1 << PASS1_BITS)); | |
221 | ||
222 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
223 | dataptr[2] = (int16_t) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
224 | CONST_BITS-PASS1_BITS); | |
225 | dataptr[6] = (int16_t) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
226 | CONST_BITS-PASS1_BITS); | |
227 | ||
228 | /* Odd part per figure 8 --- note paper omits factor of sqrt(2). | |
229 | * cK represents cos(K*pi/16). | |
230 | * i0..i3 in the paper are tmp4..tmp7 here. | |
231 | */ | |
232 | ||
233 | z1 = tmp4 + tmp7; | |
234 | z2 = tmp5 + tmp6; | |
235 | z3 = tmp4 + tmp6; | |
236 | z4 = tmp5 + tmp7; | |
237 | z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |
238 | ||
239 | tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |
240 | tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |
241 | tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |
242 | tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ | |
243 | z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ | |
244 | z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ | |
245 | z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ | |
246 | z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ | |
247 | ||
248 | z3 += z5; | |
249 | z4 += z5; | |
250 | ||
251 | dataptr[7] = (int16_t) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS); | |
252 | dataptr[5] = (int16_t) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS); | |
253 | dataptr[3] = (int16_t) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS); | |
254 | dataptr[1] = (int16_t) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS); | |
255 | ||
256 | dataptr += DCTSIZE; /* advance pointer to next row */ | |
257 | } | |
258 | } | |
259 | ||
260 | /* | |
261 | * Perform the forward DCT on one block of samples. | |
262 | */ | |
263 | ||
264 | GLOBAL(void) | |
265 | FUNC(ff_jpeg_fdct_islow)(int16_t *data) | |
266 | { | |
267 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |
268 | int tmp10, tmp11, tmp12, tmp13; | |
269 | int z1, z2, z3, z4, z5; | |
270 | int16_t *dataptr; | |
271 | int ctr; | |
272 | ||
273 | FUNC(row_fdct)(data); | |
274 | ||
275 | /* Pass 2: process columns. | |
276 | * We remove the PASS1_BITS scaling, but leave the results scaled up | |
277 | * by an overall factor of 8. | |
278 | */ | |
279 | ||
280 | dataptr = data; | |
281 | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |
282 | tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7]; | |
283 | tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7]; | |
284 | tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6]; | |
285 | tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6]; | |
286 | tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5]; | |
287 | tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5]; | |
288 | tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4]; | |
289 | tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4]; | |
290 | ||
291 | /* Even part per LL&M figure 1 --- note that published figure is faulty; | |
292 | * rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | |
293 | */ | |
294 | ||
295 | tmp10 = tmp0 + tmp3; | |
296 | tmp13 = tmp0 - tmp3; | |
297 | tmp11 = tmp1 + tmp2; | |
298 | tmp12 = tmp1 - tmp2; | |
299 | ||
300 | dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
301 | dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
302 | ||
303 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
304 | dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
305 | CONST_BITS + OUT_SHIFT); | |
306 | dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
307 | CONST_BITS + OUT_SHIFT); | |
308 | ||
309 | /* Odd part per figure 8 --- note paper omits factor of sqrt(2). | |
310 | * cK represents cos(K*pi/16). | |
311 | * i0..i3 in the paper are tmp4..tmp7 here. | |
312 | */ | |
313 | ||
314 | z1 = tmp4 + tmp7; | |
315 | z2 = tmp5 + tmp6; | |
316 | z3 = tmp4 + tmp6; | |
317 | z4 = tmp5 + tmp7; | |
318 | z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |
319 | ||
320 | tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |
321 | tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |
322 | tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |
323 | tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ | |
324 | z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ | |
325 | z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ | |
326 | z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ | |
327 | z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ | |
328 | ||
329 | z3 += z5; | |
330 | z4 += z5; | |
331 | ||
332 | dataptr[DCTSIZE*7] = DESCALE(tmp4 + z1 + z3, CONST_BITS + OUT_SHIFT); | |
333 | dataptr[DCTSIZE*5] = DESCALE(tmp5 + z2 + z4, CONST_BITS + OUT_SHIFT); | |
334 | dataptr[DCTSIZE*3] = DESCALE(tmp6 + z2 + z3, CONST_BITS + OUT_SHIFT); | |
335 | dataptr[DCTSIZE*1] = DESCALE(tmp7 + z1 + z4, CONST_BITS + OUT_SHIFT); | |
336 | ||
337 | dataptr++; /* advance pointer to next column */ | |
338 | } | |
339 | } | |
340 | ||
341 | /* | |
342 | * The secret of DCT2-4-8 is really simple -- you do the usual 1-DCT | |
343 | * on the rows and then, instead of doing even and odd, part on the columns | |
344 | * you do even part two times. | |
345 | */ | |
346 | GLOBAL(void) | |
347 | FUNC(ff_fdct248_islow)(int16_t *data) | |
348 | { | |
349 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |
350 | int tmp10, tmp11, tmp12, tmp13; | |
351 | int z1; | |
352 | int16_t *dataptr; | |
353 | int ctr; | |
354 | ||
355 | FUNC(row_fdct)(data); | |
356 | ||
357 | /* Pass 2: process columns. | |
358 | * We remove the PASS1_BITS scaling, but leave the results scaled up | |
359 | * by an overall factor of 8. | |
360 | */ | |
361 | ||
362 | dataptr = data; | |
363 | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |
364 | tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1]; | |
365 | tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3]; | |
366 | tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5]; | |
367 | tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7]; | |
368 | tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1]; | |
369 | tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3]; | |
370 | tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5]; | |
371 | tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7]; | |
372 | ||
373 | tmp10 = tmp0 + tmp3; | |
374 | tmp11 = tmp1 + tmp2; | |
375 | tmp12 = tmp1 - tmp2; | |
376 | tmp13 = tmp0 - tmp3; | |
377 | ||
378 | dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
379 | dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
380 | ||
381 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
382 | dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
383 | CONST_BITS+OUT_SHIFT); | |
384 | dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
385 | CONST_BITS+OUT_SHIFT); | |
386 | ||
387 | tmp10 = tmp4 + tmp7; | |
388 | tmp11 = tmp5 + tmp6; | |
389 | tmp12 = tmp5 - tmp6; | |
390 | tmp13 = tmp4 - tmp7; | |
391 | ||
392 | dataptr[DCTSIZE*1] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
393 | dataptr[DCTSIZE*5] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
394 | ||
395 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
396 | dataptr[DCTSIZE*3] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
397 | CONST_BITS + OUT_SHIFT); | |
398 | dataptr[DCTSIZE*7] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
399 | CONST_BITS + OUT_SHIFT); | |
400 | ||
401 | dataptr++; /* advance pointer to next column */ | |
402 | } | |
403 | } |