git.sesse.net Git - qscale/blob - libqscale.c

   1 /*
   2  * qscale: Quick, high-quality JPEG-to-JPEG scaler.
   3  * Copyright (C) 2008 Steinar H. Gunderson <sgunderson@bigfoot.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, version 2 of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  17  */
  18
  19 #include <math.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <malloc.h>
  23
  24 #include "libqscale.h"
  25
  26 /* The number of pixels to process at a time when scaling vertically. */
  27 #define CACHE_LINE_FACTOR 16
  28
  29 /* Whether to use SSE for horizontal scaling or not (requires SSE3). */
  30 #define USE_HORIZONTAL_SSE 1
  31
  32 /* Whether to use SSE for vertical scaling or not (requires only SSE1). */
  33 #define USE_VERTICAL_SSE 1
  34
  35 #if USE_VERTICAL_SSE
  36 #undef CACHE_LINE_FACTOR
  37 #define CACHE_LINE_FACTOR 16
  38 #endif
  39
  40 #ifndef M_PI
  41 #define M_PI 3.14159265358979323846264
  42 #endif
  43
  44 qscale_img *qscale_load_jpeg(const char *filename)
  45 {
  46         FILE *file = fopen(filename, "rb");
  47         qscale_img *img;
  48         if (file == NULL) {
  49                 return NULL;
  50         }
  51
  52         img = qscale_load_jpeg_from_stdio(file);
  53
  54         fclose(file);
  55         return img;
  56 }
  57
  58 qscale_img *qscale_load_jpeg_from_stdio(FILE *file)
  59 {
  60         qscale_img *img = (qscale_img *)malloc(sizeof(qscale_img));
  61         if (img == NULL) {
  62                 return NULL;
  63         }
  64
  65         img->data_y = img->data_cb = img->data_cr = NULL;
  66
  67         /* FIXME: Better error handling here (ie., return NULL). */
  68         struct jpeg_decompress_struct dinfo;
  69         struct jpeg_error_mgr jerr;
  70         dinfo.err = jpeg_std_error(&jerr);
  71         jpeg_create_decompress(&dinfo);
  72         jpeg_stdio_src(&dinfo, file);
  73         jpeg_read_header(&dinfo, TRUE);
  74         dinfo.raw_data_out = TRUE;
  75         jpeg_start_decompress(&dinfo);
  76
  77         /* We do not handle anything but YCbCr images (yet?). */
  78         if (dinfo.num_components != 3) {
  79                 qscale_destroy(img);
  80                 return NULL;
  81         }
  82
  83         img->width = dinfo.image_width;
  84         img->height = dinfo.image_height;
  85
  86         img->w0 = dinfo.image_width * dinfo.comp_info[0].h_samp_factor / dinfo.max_h_samp_factor;
  87         img->h0 = dinfo.image_height * dinfo.comp_info[0].v_samp_factor / dinfo.max_v_samp_factor;
  88
  89         img->w1 = dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor;
  90         img->h1 = dinfo.image_height * dinfo.comp_info[1].v_samp_factor / dinfo.max_v_samp_factor;
  91
  92         img->w2 = dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor;
  93         img->h2 = dinfo.image_height * dinfo.comp_info[2].v_samp_factor / dinfo.max_v_samp_factor;
  94
  95         img->samp_h0 = dinfo.comp_info[0].h_samp_factor;
  96         img->samp_v0 = dinfo.comp_info[0].v_samp_factor;
  97
  98         img->samp_h1 = dinfo.comp_info[1].h_samp_factor;
  99         img->samp_v1 = dinfo.comp_info[1].v_samp_factor;
 100
 101         img->samp_h2 = dinfo.comp_info[2].h_samp_factor;
 102         img->samp_v2 = dinfo.comp_info[2].v_samp_factor;
 103
 104         img->data_y  = (JSAMPLE*)memalign(16, dinfo.comp_info[0].height_in_blocks * dinfo.comp_info[0].width_in_blocks * DCTSIZE * DCTSIZE);
 105         img->data_cb = (JSAMPLE*)memalign(16, dinfo.comp_info[1].height_in_blocks * dinfo.comp_info[1].width_in_blocks * DCTSIZE * DCTSIZE);
 106         img->data_cr = (JSAMPLE*)memalign(16, dinfo.comp_info[2].height_in_blocks * dinfo.comp_info[2].width_in_blocks * DCTSIZE * DCTSIZE);
 107
 108         if (img->data_y == NULL || img->data_cb == NULL || img->data_cr == NULL) {
 109                 qscale_destroy(img);
 110                 return NULL;
 111         }
 112
 113         int total_lines = 0, blocks = 0;
 114         while (total_lines < dinfo.comp_info[0].height_in_blocks * DCTSIZE) {
 115                 unsigned max_lines = dinfo.max_v_samp_factor * DCTSIZE;
 116
 117                 JSAMPROW y_row_ptrs[max_lines];
 118                 JSAMPROW cb_row_ptrs[max_lines];
 119                 JSAMPROW cr_row_ptrs[max_lines];
 120                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
 121
 122                 int i;
 123                 for (i = 0; i < max_lines; ++i) {
 124                         y_row_ptrs[i]  = img->data_y  + (i+blocks*DCTSIZE*dinfo.comp_info[0].v_samp_factor) * dinfo.comp_info[0].width_in_blocks * DCTSIZE;
 125                         cb_row_ptrs[i] = img->data_cb + (i+blocks*DCTSIZE*dinfo.comp_info[1].v_samp_factor) * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
 126                         cr_row_ptrs[i] = img->data_cr + (i+blocks*DCTSIZE*dinfo.comp_info[2].v_samp_factor) * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
 127                 }
 128
 129                 total_lines += max_lines;
 130                 ++blocks;
 131
 132                 if (jpeg_read_raw_data(&dinfo, ptrs, max_lines) == 0)
 133                         break;
 134         }
 135
 136         jpeg_destroy_decompress(&dinfo);
 137         return img;
 138 }
 139
 140 void qscale_destroy(qscale_img *img)
 141 {
 142         free(img->data_y);
 143         free(img->data_cb);
 144         free(img->data_cr);
 145         free(img);
 146 }
 147
 148
 149 static double sinc(double x)
 150 {
 151         static const double cutoff = 1.220703668e-4;  /* sqrt(sqrt(eps)) */
 152
 153         if (abs(x) < cutoff) {
 154                 /* For small |x|, use Taylor series instead */
 155                 const double x2 = x * x;
 156                 const double x4 = x2 * x2;
 157
 158                 return 1.0 - x2 / 6.0 + x4 / 120.0;
 159         } else {
 160                 return sin(x) / x;
 161         }
 162 }
 163
 164 static double lanczos_tap(double x)
 165 {
 166         if (x < -3.0 || x > 3.0)
 167                 return 0.0;
 168         if (x < 0.0)
 169                 return sinc(-x*M_PI) * sinc(-x*M_PI / 3.0);
 170         else
 171                 return sinc(x*M_PI) * sinc(x*M_PI / 3.0);
 172 }
 173
 174 struct pix_desc {
 175         unsigned start, end;
 176         unsigned startcoeff;
 177 };
 178
 179 static void hscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nw, unsigned sstride, unsigned dstride)
 180 {
 181         struct pix_desc *pd = (struct pix_desc *)malloc(nw * sizeof(struct pix_desc));
 182         int size_coeffs = 8;
 183         float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
 184         int num_coeffs = 0;
 185         int x, y;
 186         double sf = (double)w / (double)nw;
 187         double support = (w > nw) ? (3.0 * sf) : (3.0 / sf);
 188
 189         /* calculate the filter */
 190         for (x = 0; x < nw; ++x) {
 191                 int start = ceil(x * sf - support);
 192                 int end = floor(x * sf + support);
 193                 int sx;
 194                 double sum = 0.0;
 195
 196                 if (start < 0) {
 197                         start = 0;
 198                 }
 199                 if (end > w - 1) {
 200                         end = w - 1;
 201                 }
 202
 203 #if USE_HORIZONTAL_SSE
 204                 /* round up so we get a multiple of four for the SSE code */
 205                 int num = (end - start + 1);
 206                 if (num % 4 != 0) {
 207                         /* prefer aligning it if possible */
 208                         if (start % 4 != 0 && start % 4 <= num % 4) {
 209                                 num += start % 4;
 210                                 start -= start % 4;
 211                         }
 212                         if (num % 4 != 0) {
 213                                 end += 4 - (num % 4);
 214                         }
 215                 }
 216 #endif
 217
 218                 pd[x].start = start;
 219                 pd[x].end = end;
 220                 pd[x].startcoeff = num_coeffs;
 221
 222                 for (sx = start; sx <= end; ++sx) {
 223                         double nd = (w > nw) ? (sx/sf - x) : (sx - x*sf);
 224                         double f = lanczos_tap(nd);
 225                         if (num_coeffs == size_coeffs) {
 226                                 size_coeffs <<= 1;
 227                                 coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
 228                         }
 229
 230                         coeffs[num_coeffs++] = f;
 231                         sum += f;
 232                 }
 233
 234                 for (sx = start; sx <= end; ++sx) {
 235                         coeffs[pd[x].startcoeff + sx - start] /= sum;
 236                 }
 237         }
 238
 239         for (y = 0; y < h; ++y) {
 240                 float *sptr = pix + y*sstride;
 241                 unsigned char *dptr = npix + y*dstride;
 242                 unsigned char ch;
 243                 for (x = 0; x < nw; ++x) {
 244 #if USE_HORIZONTAL_SSE
 245                         int result;
 246                         float acc;
 247                         long tmp;
 248                         static const float low = 0.0, high = 255.0;
 249                         __asm__ (
 250                                 "pxor %1, %1               \n"
 251                                 "xor %2, %2                \n"
 252                                 "0:                        \n"
 253                                 "movups (%4,%2),%%xmm1     \n"
 254                                 "movups (%3,%2),%%xmm2     \n"
 255                                 "mulps %%xmm2,%%xmm1       \n"
 256                                 "addps %%xmm1,%1           \n"
 257                                 "add $16,%2                \n"
 258                                 "dec %5                    \n"
 259                                 "jnz 0b                    \n"
 260                                 "haddps %1,%1              \n"
 261                                 "haddps %1,%1              \n"
 262                                 "maxss %6,%1               \n"
 263                                 "minss %7,%1               \n"
 264                                 "cvtss2si %1,%0            \n"
 265                                 : "=r" (result),
 266                                   "=&x" (acc),
 267                                   "=&r" (tmp)
 268                                 : "r" (&coeffs[pd[x].startcoeff]),
 269                                   "r" (&sptr[pd[x].start]),
 270                                   "r" ((pd[x].end - pd[x].start + 1)/4),
 271                                   "m" (low),
 272                                   "m" (high)
 273                                 : "memory", "xmm1", "xmm2"
 274                         );
 275
 276                         *dptr++ = (unsigned char)result;
 277 #else
 278                         float acc = 0.0;
 279                         float *cf = &coeffs[pd[x].startcoeff];
 280                         unsigned sx;
 281
 282                         for (sx = pd[x].start; sx <= pd[x].end; ++sx) {
 283                                 acc += sptr[sx] * *cf++;
 284                         }
 285
 286                         if (acc < 0.0)
 287                                 ch = 0;
 288                         else if (acc > 255.0)
 289                                 ch = 255;
 290                         else
 291                                 ch = (unsigned char)acc;
 292                         *dptr++ = ch;
 293 #endif
 294                 }
 295                 ch = dptr[-1];
 296                 for ( ; x < dstride; ++x) {
 297                         *dptr++ = ch;
 298                 }
 299         }
 300 }
 301
 302 static void vscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nh, unsigned dstride)
 303 {
 304         struct pix_desc *pd = (struct pix_desc *)malloc(nh * sizeof(struct pix_desc));
 305         int size_coeffs = 8;
 306         float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
 307         int num_coeffs = 0;
 308         int x, y, sy;
 309         double sf = (double)h / (double)nh;
 310         double support = (h > nh) ? (3.0 * sf) : (3.0 / sf);
 311
 312         /* calculate the filter */
 313         for (y = 0; y < nh; ++y) {
 314                 int start = ceil(y * sf - support);
 315                 int end = floor(y * sf + support);
 316                 double sum = 0.0;
 317
 318                 if (start < 0) {
 319                         start = 0;
 320                 }
 321                 if (end > h - 1) {
 322                         end = h - 1;
 323                 }
 324
 325                 pd[y].start = start;
 326                 pd[y].end = end;
 327                 pd[y].startcoeff = num_coeffs;
 328
 329                 for (sy = start; sy <= end; ++sy) {
 330                         double nd = (h > nh) ? (sy/sf - y) : (sy - y*sf);
 331                         double f = lanczos_tap(nd);
 332                         if (num_coeffs == size_coeffs) {
 333                                 size_coeffs <<= 1;
 334                                 coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
 335                         }
 336
 337                         coeffs[num_coeffs++] = f;
 338                         sum += f;
 339                 }
 340
 341                 for (sy = start; sy <= end; ++sy) {
 342                         coeffs[pd[y].startcoeff + sy - start] /= sum;
 343                 }
 344         }
 345
 346 #if CACHE_LINE_FACTOR > 1
 347         for (x = 0; x < (w/CACHE_LINE_FACTOR) * CACHE_LINE_FACTOR; x += CACHE_LINE_FACTOR) {
 348                 unsigned char *sptr = pix + x;
 349                 float *dptr = npix + x;
 350                 for (y = 0; y < nh; ++y) {
 351 #if USE_VERTICAL_SSE
 352                         /*
 353                          * xmm0 - xmm3: acc[0..15]
 354                          * xmm4: current filter coefficient
 355                          * xmm5, xmm6, xmm7: scratchpad
 356                          */
 357                         __asm__ (
 358                                 /* clear */
 359                                 "pxor %%xmm0, %%xmm0          \n"
 360                                 "pxor %%xmm1, %%xmm1          \n"
 361                                 "pxor %%xmm2, %%xmm2          \n"
 362                                 "pxor %%xmm3, %%xmm3          \n"
 363
 364                                 /* main loop */
 365                                 "0:                           \n"
 366
 367                                 /* a zero is useful during unpacking */
 368                                 "pxor %%xmm4, %%xmm4          \n"
 369
 370                                 /* fetch all 16 source bytes */
 371                                 "movups (%0), %%xmm5          \n"
 372                                 "prefetcht0 (%0,%3,4)         \n"
 373
 374                                 /* unpack into words (xmm5, xmm7) */
 375                                 "movaps %%xmm5, %%xmm7        \n"
 376                                 "punpcklbw %%xmm4, %%xmm5     \n"
 377                                 "punpckhbw %%xmm4, %%xmm7     \n"
 378
 379                                 /* unpack xmm5 into dwords (xmm5, xmm6) */
 380                                 "movaps %%xmm5, %%xmm6        \n"
 381                                 "punpcklwd %%xmm4, %%xmm5     \n"
 382                                 "punpckhwd %%xmm4, %%xmm6     \n"
 383
 384                                 /* convert xmm5, xmm6 to floats */
 385                                 "cvtdq2ps %%xmm5, %%xmm5      \n"
 386                                 "cvtdq2ps %%xmm6, %%xmm6      \n"
 387
 388                                 /* fetch the coefficient */
 389                                 "movss (%2), %%xmm4           \n"
 390                                 "shufps $0x0, %%xmm4, %%xmm4  \n"
 391
 392                                 /* do the muls for xmm5 and xmm6 */
 393                                 "mulps %%xmm4, %%xmm5         \n"
 394                                 "mulps %%xmm4, %%xmm6         \n"
 395                                 "addps %%xmm5, %%xmm0         \n"
 396                                 "addps %%xmm6, %%xmm1         \n"
 397
 398                                 /* get the zero back again */
 399                                 "pxor %%xmm4, %%xmm4          \n"
 400
 401                                 /* unpack xmm7 into dwords (xmm7, xmm6) */
 402                                 "movaps %%xmm7, %%xmm6        \n"
 403                                 "punpcklwd %%xmm4, %%xmm7     \n"
 404                                 "punpckhwd %%xmm4, %%xmm6     \n"
 405
 406                                 /* convert xmm7, xmm6 to floats */
 407                                 "cvtdq2ps %%xmm7, %%xmm7      \n"
 408                                 "cvtdq2ps %%xmm6, %%xmm6      \n"
 409
 410                                 /* fetch the coefficient */
 411                                 "movss (%2), %%xmm4           \n"
 412                                 "shufps $0x0, %%xmm4, %%xmm4  \n"
 413
 414                                 /* do the second set of muls */
 415                                 "mulps %%xmm4, %%xmm7         \n"
 416                                 "mulps %%xmm4, %%xmm6         \n"
 417                                 "addps %%xmm7, %%xmm2         \n"
 418                                 "addps %%xmm6, %%xmm3         \n"
 419
 420                                 /* move along, and loop */
 421                                 "add $4, %2                   \n"
 422                                 "add %3, %0                   \n"
 423                                 "dec %1                       \n"
 424                                 "jnz 0b                       \n"
 425
 426                                 /* store the values */
 427                                 "movaps %%xmm0, (%4)          \n"
 428                                 "movaps %%xmm1, 16(%4)        \n"
 429                                 "movaps %%xmm2, 32(%4)        \n"
 430                                 "movaps %%xmm3, 48(%4)        \n"
 431                                 : :
 432                                 "r" (&sptr[pd[y].start * w]),        /* 0: srcptr base */
 433                                 "r" (pd[y].end - pd[y].start + 1),   /* 1: filter len */
 434                                 "r" (&coeffs[pd[y].startcoeff]),     /* 2: coeffs base */
 435                                 "r" ((long)w),                       /* 3: stride */
 436                                 "r" (dptr)                           /* 4: dstptr base */
 437                                 : "memory", "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7"
 438                         );
 439 #else
 440                         int i;
 441                         float acc[CACHE_LINE_FACTOR];
 442                         for (i = 0; i < CACHE_LINE_FACTOR; ++i)
 443                                 acc[i] = 0.0;
 444                         float *cf = &coeffs[pd[y].startcoeff];
 445                         unsigned sy;
 446
 447                         for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 448                                 for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
 449                                         acc[i] += sptr[sy * w + i] * *cf;
 450                                 }
 451                                 ++cf;
 452                         }
 453
 454                         for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
 455                                 dptr[i] = acc[i];
 456                         }
 457 #endif
 458                         dptr += dstride;
 459                 }
 460         }
 461         for (x = (x/CACHE_LINE_FACTOR)*CACHE_LINE_FACTOR; x < w; ++x) {
 462 #else
 463         for (x = 0; x < w; ++x) {
 464 #endif
 465                 unsigned char *sptr = pix + x;
 466                 float *dptr = npix + x;
 467                 for (y = 0; y < nh; ++y) {
 468                         float acc = 0.0;
 469                         float *cf = &coeffs[pd[y].startcoeff];
 470                         unsigned sy;
 471
 472                         for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 473                                 acc += sptr[sy * w] * *cf++;
 474                         }
 475
 476                         *dptr = acc;
 477                         dptr += dstride;
 478                 }
 479         }
 480 }
 481
 482 qscale_img *qscale_scale(qscale_img *src, unsigned width, unsigned height, unsigned samp_h0, unsigned samp_v0, unsigned samp_h1, unsigned samp_v1, unsigned samp_h2, unsigned samp_v2, enum qscale_scaling_filter scaling_filter)
 483 {
 484         qscale_img *dst = (qscale_img *)malloc(sizeof(qscale_img));
 485         if (dst == NULL) {
 486                 return NULL;
 487         }
 488
 489         dst->width = width;
 490         dst->height = height;
 491
 492         unsigned max_samp_h, max_samp_v;
 493         max_samp_h = samp_h0;
 494         if (samp_h1 > max_samp_h)
 495                 max_samp_h = samp_h1;
 496         if (samp_h2 > max_samp_h)
 497                 max_samp_h = samp_h2;
 498
 499         max_samp_v = samp_v0;
 500         if (samp_v1 > max_samp_v)
 501                 max_samp_v = samp_v1;
 502         if (samp_v2 > max_samp_v)
 503                 max_samp_v = samp_v2;
 504
 505         dst->w0 = width * samp_h0 / max_samp_h;
 506         dst->h0 = height * samp_v0 / max_samp_v;
 507
 508         dst->w1 = width * samp_h1 / max_samp_h;
 509         dst->h1 = height * samp_v1 / max_samp_v;
 510
 511         dst->w2 = width * samp_h2 / max_samp_h;
 512         dst->h2 = height * samp_v2 / max_samp_v;
 513
 514         dst->samp_h0 = samp_h0;
 515         dst->samp_v0 = samp_v0;
 516
 517         dst->samp_h1 = samp_h1;
 518         dst->samp_v1 = samp_v1;
 519
 520         dst->samp_h2 = samp_h2;
 521         dst->samp_v2 = samp_v2;
 522
 523         unsigned dstride0 = (dst->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
 524         unsigned dstride1 = (dst->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
 525         unsigned dstride2 = (dst->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
 526
 527         unsigned sstride0 = (src->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
 528         unsigned sstride1 = (src->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
 529         unsigned sstride2 = (src->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
 530
 531         /* FIXME: handle out-of-memory gracefully */
 532         {
 533                 float *npix = (float*)memalign(16, sstride0 * dst->h0 * sizeof(float));
 534                 vscale(src->data_y, npix, sstride0, src->h0, dst->h0, sstride0);
 535                 dst->data_y = (unsigned char *)malloc(dst->h0 * dstride0);
 536                 hscale(npix, dst->data_y, src->w0, dst->h0, dst->w0, sstride0, dstride0);
 537                 free(npix);
 538         }
 539         {
 540                 float *npix = (float*)memalign(16, sstride1 * dst->h1 * sizeof(float));
 541                 vscale(src->data_cr, npix, sstride1, src->h1, dst->h1, sstride1);
 542                 dst->data_cr = (unsigned char *)malloc(dst->h1 * dstride1);
 543                 hscale(npix, dst->data_cr, src->w1, dst->h1, dst->w1, sstride1, dstride1);
 544                 free(npix);
 545         }
 546         {
 547                 float *npix = (float*)memalign(16, sstride2 * dst->h2 * sizeof(float));
 548                 vscale(src->data_cb, npix, sstride2, src->h2, dst->h2, sstride2);
 549                 dst->data_cb = (unsigned char *)malloc(dst->h2 * dstride2);
 550                 hscale(npix, dst->data_cb, src->w2, dst->h2, dst->w2, sstride2, dstride2);
 551                 free(npix);
 552         }
 553
 554         return dst;
 555 }
 556
 557 int qscale_save_jpeg(const qscale_img *img, const char *filename, unsigned jpeg_quality, enum qscale_jpeg_mode jpeg_mode)
 558 {
 559         FILE *file = fopen(filename, "wb");
 560         if (file == NULL) {
 561                 return -1;
 562         }
 563
 564         int err = qscale_save_jpeg_to_stdio(img, file, jpeg_quality, jpeg_mode);
 565
 566         fclose(file);
 567         return err;
 568 }
 569
 570 int qscale_save_jpeg_to_stdio(const qscale_img *img, FILE *file, unsigned jpeg_quality, enum qscale_jpeg_mode jpeg_mode)
 571 {
 572         struct jpeg_compress_struct cinfo;
 573         struct jpeg_error_mgr jerr;
 574         cinfo.err = jpeg_std_error(&jerr);
 575         jpeg_create_compress(&cinfo);
 576         jpeg_stdio_dest(&cinfo, file);
 577         cinfo.input_components = 3;
 578         jpeg_set_defaults(&cinfo);
 579         jpeg_set_quality(&cinfo, jpeg_quality, FALSE);
 580         cinfo.image_width = img->width;
 581         cinfo.image_height = img->height;
 582         cinfo.raw_data_in = TRUE;
 583         jpeg_set_colorspace(&cinfo, JCS_YCbCr);
 584         cinfo.comp_info[0].h_samp_factor = img->samp_h0;
 585         cinfo.comp_info[0].v_samp_factor = img->samp_v0;
 586         cinfo.comp_info[1].h_samp_factor = img->samp_h1;
 587         cinfo.comp_info[1].v_samp_factor = img->samp_v1;
 588         cinfo.comp_info[2].h_samp_factor = img->samp_h2;
 589         cinfo.comp_info[2].v_samp_factor = img->samp_v2;
 590         jpeg_start_compress(&cinfo, TRUE);
 591
 592         unsigned dstride0 = (img->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
 593         unsigned dstride1 = (img->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
 594         unsigned dstride2 = (img->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
 595
 596         int total_lines = 0;
 597         int blocks = 0;
 598         while (total_lines < cinfo.comp_info[0].height_in_blocks * DCTSIZE) {
 599                 unsigned max_lines = cinfo.max_v_samp_factor * DCTSIZE;
 600
 601                 JSAMPROW y_row_ptrs[max_lines];
 602                 JSAMPROW cb_row_ptrs[max_lines];
 603                 JSAMPROW cr_row_ptrs[max_lines];
 604                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
 605                 int i;
 606
 607                 for (i = 0; i < max_lines; ++i) {
 608                         /* simple edge extension */
 609                         int yline = i + blocks*DCTSIZE*cinfo.comp_info[0].v_samp_factor;
 610                         if (yline > img->h0 - 1)
 611                                 yline = img->h0 - 1;
 612
 613                         int cbline = i + blocks*DCTSIZE*cinfo.comp_info[1].v_samp_factor;
 614                         if (cbline > img->h1 - 1)
 615                                 cbline = img->h1 - 1;
 616
 617                         int crline = i + blocks*DCTSIZE*cinfo.comp_info[2].v_samp_factor;
 618                         if (crline > img->h2 - 1)
 619                                 crline = img->h2 - 1;
 620
 621                         y_row_ptrs[i]  = img->data_y  + yline * dstride0;
 622                         cb_row_ptrs[i] = img->data_cb + cbline * dstride1;
 623                         cr_row_ptrs[i] = img->data_cr + crline * dstride2;
 624                 }
 625
 626                 total_lines += max_lines;
 627                 ++blocks;
 628
 629                 jpeg_write_raw_data(&cinfo, ptrs, max_lines);
 630         }
 631         jpeg_finish_compress(&cinfo);
 632         jpeg_destroy_compress(&cinfo);
 633
 634         return 0;
 635 }