libavcodec/pngdec.c

   1 /*
   2  * PNG image format
   3  * Copyright (c) 2003 Fabrice Bellard
   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 #include "avcodec.h"
  22 #include "bytestream.h"
  23 #include "png.h"
  24 #include "dsputil.h"
  25
  26 /* TODO:
  27  * - add 2, 4 and 16 bit depth support
  28  */
  29
  30 #include <zlib.h>
  31
  32 //#define DEBUG
  33
  34 typedef struct PNGDecContext {
  35     DSPContext dsp;
  36
  37     const uint8_t *bytestream;
  38     const uint8_t *bytestream_start;
  39     const uint8_t *bytestream_end;
  40     AVFrame picture1, picture2;
  41     AVFrame *current_picture, *last_picture;
  42
  43     int state;
  44     int width, height;
  45     int bit_depth;
  46     int color_type;
  47     int compression_type;
  48     int interlace_type;
  49     int filter_type;
  50     int channels;
  51     int bits_per_pixel;
  52     int bpp;
  53
  54     uint8_t *image_buf;
  55     int image_linesize;
  56     uint32_t palette[256];
  57     uint8_t *crow_buf;
  58     uint8_t *last_row;
  59     uint8_t *tmp_row;
  60     int pass;
  61     int crow_size; /* compressed row size (include filter type) */
  62     int row_size; /* decompressed row size */
  63     int pass_row_size; /* decompress row size of the current pass */
  64     int y;
  65     z_stream zstream;
  66 } PNGDecContext;
  67
  68 /* Mask to determine which y pixels can be written in a pass */
  69 static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
  70     0xff, 0xff, 0x0f, 0xcc, 0x33, 0xff, 0x55,
  71 };
  72
  73 /* Mask to determine which pixels to overwrite while displaying */
  74 static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
  75     0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
  76 };
  77
  78 /* NOTE: we try to construct a good looking image at each pass. width
  79    is the original image width. We also do pixel format conversion at
  80    this stage */
  81 static void png_put_interlaced_row(uint8_t *dst, int width,
  82                                    int bits_per_pixel, int pass,
  83                                    int color_type, const uint8_t *src)
  84 {
  85     int x, mask, dsp_mask, j, src_x, b, bpp;
  86     uint8_t *d;
  87     const uint8_t *s;
  88
  89     mask = ff_png_pass_mask[pass];
  90     dsp_mask = png_pass_dsp_mask[pass];
  91     switch(bits_per_pixel) {
  92     case 1:
  93         /* we must initialize the line to zero before writing to it */
  94         if (pass == 0)
  95             memset(dst, 0, (width + 7) >> 3);
  96         src_x = 0;
  97         for(x = 0; x < width; x++) {
  98             j = (x & 7);
  99             if ((dsp_mask << j) & 0x80) {
 100                 b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
 101                 dst[x >> 3] |= b << (7 - j);
 102             }
 103             if ((mask << j) & 0x80)
 104                 src_x++;
 105         }
 106         break;
 107     default:
 108         bpp = bits_per_pixel >> 3;
 109         d = dst;
 110         s = src;
 111         if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 112             for(x = 0; x < width; x++) {
 113                 j = x & 7;
 114                 if ((dsp_mask << j) & 0x80) {
 115                     *(uint32_t *)d = (s[3] << 24) | (s[0] << 16) | (s[1] << 8) | s[2];
 116                 }
 117                 d += bpp;
 118                 if ((mask << j) & 0x80)
 119                     s += bpp;
 120             }
 121         } else {
 122             for(x = 0; x < width; x++) {
 123                 j = x & 7;
 124                 if ((dsp_mask << j) & 0x80) {
 125                     memcpy(d, s, bpp);
 126                 }
 127                 d += bpp;
 128                 if ((mask << j) & 0x80)
 129                     s += bpp;
 130             }
 131         }
 132         break;
 133     }
 134 }
 135
 136 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
 137 {
 138     int i;
 139     for(i = 0; i < w; i++) {
 140         int a, b, c, p, pa, pb, pc;
 141
 142         a = dst[i - bpp];
 143         b = top[i];
 144         c = top[i - bpp];
 145
 146         p = b - c;
 147         pc = a - c;
 148
 149         pa = abs(p);
 150         pb = abs(pc);
 151         pc = abs(p + pc);
 152
 153         if (pa <= pb && pa <= pc)
 154             p = a;
 155         else if (pb <= pc)
 156             p = b;
 157         else
 158             p = c;
 159         dst[i] = p + src[i];
 160     }
 161 }
 162
 163 #define UNROLL1(bpp, op) {\
 164                  r = dst[0];\
 165     if(bpp >= 2) g = dst[1];\
 166     if(bpp >= 3) b = dst[2];\
 167     if(bpp >= 4) a = dst[3];\
 168     for(; i < size; i+=bpp) {\
 169         dst[i+0] = r = op(r, src[i+0], last[i+0]);\
 170         if(bpp == 1) continue;\
 171         dst[i+1] = g = op(g, src[i+1], last[i+1]);\
 172         if(bpp == 2) continue;\
 173         dst[i+2] = b = op(b, src[i+2], last[i+2]);\
 174         if(bpp == 3) continue;\
 175         dst[i+3] = a = op(a, src[i+3], last[i+3]);\
 176     }\
 177 }
 178
 179 #define UNROLL_FILTER(op)\
 180          if(bpp == 1) UNROLL1(1, op)\
 181     else if(bpp == 2) UNROLL1(2, op)\
 182     else if(bpp == 3) UNROLL1(3, op)\
 183     else if(bpp == 4) UNROLL1(4, op)\
 184     else {\
 185         for (; i < size; i += bpp) {\
 186             int j;\
 187             for (j = 0; j < bpp; j++)\
 188                 dst[i+j] = op(dst[i+j-bpp], src[i+j], last[i+j]);\
 189         }\
 190     }
 191
 192 /* NOTE: 'dst' can be equal to 'last' */
 193 static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
 194                            uint8_t *src, uint8_t *last, int size, int bpp)
 195 {
 196     int i, p, r, g, b, a;
 197
 198     switch(filter_type) {
 199     case PNG_FILTER_VALUE_NONE:
 200         memcpy(dst, src, size);
 201         break;
 202     case PNG_FILTER_VALUE_SUB:
 203         for(i = 0; i < bpp; i++) {
 204             dst[i] = src[i];
 205         }
 206         if(bpp == 4) {
 207             p = *(int*)dst;
 208             for(; i < size; i+=bpp) {
 209                 int s = *(int*)(src+i);
 210                 p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
 211                 *(int*)(dst+i) = p;
 212             }
 213         } else {
 214 #define OP_SUB(x,s,l) x+s
 215             UNROLL_FILTER(OP_SUB);
 216         }
 217         break;
 218     case PNG_FILTER_VALUE_UP:
 219         dsp->add_bytes_l2(dst, src, last, size);
 220         break;
 221     case PNG_FILTER_VALUE_AVG:
 222         for(i = 0; i < bpp; i++) {
 223             p = (last[i] >> 1);
 224             dst[i] = p + src[i];
 225         }
 226 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
 227         UNROLL_FILTER(OP_AVG);
 228         break;
 229     case PNG_FILTER_VALUE_PAETH:
 230         for(i = 0; i < bpp; i++) {
 231             p = last[i];
 232             dst[i] = p + src[i];
 233         }
 234         if(bpp > 1 && size > 4) {
 235             // would write off the end of the array if we let it process the last pixel with bpp=3
 236             int w = bpp==4 ? size : size-3;
 237             dsp->add_png_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
 238             i = w;
 239         }
 240         ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
 241         break;
 242     }
 243 }
 244
 245 static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
 246 {
 247     int j;
 248     unsigned int r, g, b, a;
 249
 250     for(j = 0;j < width; j++) {
 251         r = src[0];
 252         g = src[1];
 253         b = src[2];
 254         a = src[3];
 255         if(loco) {
 256             r = (r+g)&0xff;
 257             b = (b+g)&0xff;
 258         }
 259         *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
 260         dst += 4;
 261         src += 4;
 262     }
 263 }
 264
 265 static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
 266 {
 267     if(loco)
 268         convert_to_rgb32_loco(dst, src, width, 1);
 269     else
 270         convert_to_rgb32_loco(dst, src, width, 0);
 271 }
 272
 273 static void deloco_rgb24(uint8_t *dst, int size)
 274 {
 275     int i;
 276     for(i=0; i<size; i+=3) {
 277         int g = dst[i+1];
 278         dst[i+0] += g;
 279         dst[i+2] += g;
 280     }
 281 }
 282
 283 /* process exactly one decompressed row */
 284 static void png_handle_row(PNGDecContext *s)
 285 {
 286     uint8_t *ptr, *last_row;
 287     int got_line;
 288
 289     if (!s->interlace_type) {
 290         ptr = s->image_buf + s->image_linesize * s->y;
 291         /* need to swap bytes correctly for RGB_ALPHA */
 292         if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 293             png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 294                            s->last_row, s->row_size, s->bpp);
 295             convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
 296             FFSWAP(uint8_t*, s->last_row, s->tmp_row);
 297         } else {
 298             /* in normal case, we avoid one copy */
 299             if (s->y == 0)
 300                 last_row = s->last_row;
 301             else
 302                 last_row = ptr - s->image_linesize;
 303
 304             png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
 305                            last_row, s->row_size, s->bpp);
 306         }
 307         /* loco lags by 1 row so that it doesn't interfere with top prediction */
 308         if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
 309             s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
 310             deloco_rgb24(ptr - s->image_linesize, s->row_size);
 311         s->y++;
 312         if (s->y == s->height) {
 313             s->state |= PNG_ALLIMAGE;
 314             if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
 315                 s->color_type == PNG_COLOR_TYPE_RGB)
 316                 deloco_rgb24(ptr, s->row_size);
 317         }
 318     } else {
 319         got_line = 0;
 320         for(;;) {
 321             ptr = s->image_buf + s->image_linesize * s->y;
 322             if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
 323                 /* if we already read one row, it is time to stop to
 324                    wait for the next one */
 325                 if (got_line)
 326                     break;
 327                 png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 328                                s->last_row, s->pass_row_size, s->bpp);
 329                 FFSWAP(uint8_t*, s->last_row, s->tmp_row);
 330                 got_line = 1;
 331             }
 332             if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
 333                 /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
 334                 png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
 335                                        s->color_type, s->last_row);
 336             }
 337             s->y++;
 338             if (s->y == s->height) {
 339                 for(;;) {
 340                     if (s->pass == NB_PASSES - 1) {
 341                         s->state |= PNG_ALLIMAGE;
 342                         goto the_end;
 343                     } else {
 344                         s->pass++;
 345                         s->y = 0;
 346                         s->pass_row_size = ff_png_pass_row_size(s->pass,
 347                                                              s->bits_per_pixel,
 348                                                              s->width);
 349                         s->crow_size = s->pass_row_size + 1;
 350                         if (s->pass_row_size != 0)
 351                             break;
 352                         /* skip pass if empty row */
 353                     }
 354                 }
 355             }
 356         }
 357     the_end: ;
 358     }
 359 }
 360
 361 static int png_decode_idat(PNGDecContext *s, int length)
 362 {
 363     int ret;
 364     s->zstream.avail_in = length;
 365     s->zstream.next_in = s->bytestream;
 366     s->bytestream += length;
 367
 368     if(s->bytestream > s->bytestream_end)
 369         return -1;
 370
 371     /* decode one line if possible */
 372     while (s->zstream.avail_in > 0) {
 373         ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
 374         if (ret != Z_OK && ret != Z_STREAM_END) {
 375             return -1;
 376         }
 377         if (s->zstream.avail_out == 0) {
 378             if (!(s->state & PNG_ALLIMAGE)) {
 379                 png_handle_row(s);
 380             }
 381             s->zstream.avail_out = s->crow_size;
 382             s->zstream.next_out = s->crow_buf;
 383         }
 384     }
 385     return 0;
 386 }
 387
 388 static int decode_frame(AVCodecContext *avctx,
 389                         void *data, int *data_size,
 390                         AVPacket *avpkt)
 391 {
 392     const uint8_t *buf = avpkt->data;
 393     int buf_size = avpkt->size;
 394     PNGDecContext * const s = avctx->priv_data;
 395     AVFrame *picture = data;
 396     AVFrame *p;
 397     uint8_t *crow_buf_base = NULL;
 398     uint32_t tag, length;
 399     int ret, crc;
 400
 401     FFSWAP(AVFrame *, s->current_picture, s->last_picture);
 402     avctx->coded_frame= s->current_picture;
 403     p = s->current_picture;
 404
 405     s->bytestream_start=
 406     s->bytestream= buf;
 407     s->bytestream_end= buf + buf_size;
 408
 409     /* check signature */
 410     if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&
 411         memcmp(s->bytestream, ff_mngsig, 8) != 0)
 412         return -1;
 413     s->bytestream+= 8;
 414     s->y=
 415     s->state=0;
 416 //    memset(s, 0, sizeof(PNGDecContext));
 417     /* init the zlib */
 418     s->zstream.zalloc = ff_png_zalloc;
 419     s->zstream.zfree = ff_png_zfree;
 420     s->zstream.opaque = NULL;
 421     ret = inflateInit(&s->zstream);
 422     if (ret != Z_OK)
 423         return -1;
 424     for(;;) {
 425         int tag32;
 426         if (s->bytestream >= s->bytestream_end)
 427             goto fail;
 428         length = bytestream_get_be32(&s->bytestream);
 429         if (length > 0x7fffffff)
 430             goto fail;
 431         tag32 = bytestream_get_be32(&s->bytestream);
 432         tag = bswap_32(tag32);
 433 #ifdef DEBUG
 434         av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
 435                (tag & 0xff),
 436                ((tag >> 8) & 0xff),
 437                ((tag >> 16) & 0xff),
 438                ((tag >> 24) & 0xff), length);
 439 #endif
 440         switch(tag) {
 441         case MKTAG('I', 'H', 'D', 'R'):
 442             if (length != 13)
 443                 goto fail;
 444             s->width = bytestream_get_be32(&s->bytestream);
 445             s->height = bytestream_get_be32(&s->bytestream);
 446             if(avcodec_check_dimensions(avctx, s->width, s->height)){
 447                 s->width= s->height= 0;
 448                 goto fail;
 449             }
 450             s->bit_depth = *s->bytestream++;
 451             s->color_type = *s->bytestream++;
 452             s->compression_type = *s->bytestream++;
 453             s->filter_type = *s->bytestream++;
 454             s->interlace_type = *s->bytestream++;
 455             crc = bytestream_get_be32(&s->bytestream);
 456             s->state |= PNG_IHDR;
 457 #ifdef DEBUG
 458             av_log(avctx, AV_LOG_DEBUG, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
 459                    s->width, s->height, s->bit_depth, s->color_type,
 460                    s->compression_type, s->filter_type, s->interlace_type);
 461 #endif
 462             break;
 463         case MKTAG('I', 'D', 'A', 'T'):
 464             if (!(s->state & PNG_IHDR))
 465                 goto fail;
 466             if (!(s->state & PNG_IDAT)) {
 467                 /* init image info */
 468                 avctx->width = s->width;
 469                 avctx->height = s->height;
 470
 471                 s->channels = ff_png_get_nb_channels(s->color_type);
 472                 s->bits_per_pixel = s->bit_depth * s->channels;
 473                 s->bpp = (s->bits_per_pixel + 7) >> 3;
 474                 s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
 475
 476                 if (s->bit_depth == 8 &&
 477                     s->color_type == PNG_COLOR_TYPE_RGB) {
 478                     avctx->pix_fmt = PIX_FMT_RGB24;
 479                 } else if (s->bit_depth == 8 &&
 480                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 481                     avctx->pix_fmt = PIX_FMT_RGB32;
 482                 } else if (s->bit_depth == 8 &&
 483                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 484                     avctx->pix_fmt = PIX_FMT_GRAY8;
 485                 } else if (s->bit_depth == 16 &&
 486                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 487                     avctx->pix_fmt = PIX_FMT_GRAY16BE;
 488                 } else if (s->bit_depth == 16 &&
 489                            s->color_type == PNG_COLOR_TYPE_RGB) {
 490                     avctx->pix_fmt = PIX_FMT_RGB48BE;
 491                 } else if (s->bit_depth == 1 &&
 492                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 493                     avctx->pix_fmt = PIX_FMT_MONOBLACK;
 494                 } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
 495                     avctx->pix_fmt = PIX_FMT_PAL8;
 496                 } else {
 497                     goto fail;
 498                 }
 499                 if(p->data[0])
 500                     avctx->release_buffer(avctx, p);
 501
 502                 p->reference= 0;
 503                 if(avctx->get_buffer(avctx, p) < 0){
 504                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 505                     goto fail;
 506                 }
 507                 p->pict_type= FF_I_TYPE;
 508                 p->key_frame= 1;
 509                 p->interlaced_frame = !!s->interlace_type;
 510
 511                 /* compute the compressed row size */
 512                 if (!s->interlace_type) {
 513                     s->crow_size = s->row_size + 1;
 514                 } else {
 515                     s->pass = 0;
 516                     s->pass_row_size = ff_png_pass_row_size(s->pass,
 517                                                          s->bits_per_pixel,
 518                                                          s->width);
 519                     s->crow_size = s->pass_row_size + 1;
 520                 }
 521 #ifdef DEBUG
 522                 av_log(avctx, AV_LOG_DEBUG, "row_size=%d crow_size =%d\n",
 523                        s->row_size, s->crow_size);
 524 #endif
 525                 s->image_buf = p->data[0];
 526                 s->image_linesize = p->linesize[0];
 527                 /* copy the palette if needed */
 528                 if (s->color_type == PNG_COLOR_TYPE_PALETTE)
 529                     memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
 530                 /* empty row is used if differencing to the first row */
 531                 s->last_row = av_mallocz(s->row_size);
 532                 if (!s->last_row)
 533                     goto fail;
 534                 if (s->interlace_type ||
 535                     s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 536                     s->tmp_row = av_malloc(s->row_size);
 537                     if (!s->tmp_row)
 538                         goto fail;
 539                 }
 540                 /* compressed row */
 541                 crow_buf_base = av_malloc(s->row_size + 16);
 542                 if (!crow_buf_base)
 543                     goto fail;
 544
 545                 /* we want crow_buf+1 to be 16-byte aligned */
 546                 s->crow_buf = crow_buf_base + 15;
 547                 s->zstream.avail_out = s->crow_size;
 548                 s->zstream.next_out = s->crow_buf;
 549             }
 550             s->state |= PNG_IDAT;
 551             if (png_decode_idat(s, length) < 0)
 552                 goto fail;
 553             /* skip crc */
 554             crc = bytestream_get_be32(&s->bytestream);
 555             break;
 556         case MKTAG('P', 'L', 'T', 'E'):
 557             {
 558                 int n, i, r, g, b;
 559
 560                 if ((length % 3) != 0 || length > 256 * 3)
 561                     goto skip_tag;
 562                 /* read the palette */
 563                 n = length / 3;
 564                 for(i=0;i<n;i++) {
 565                     r = *s->bytestream++;
 566                     g = *s->bytestream++;
 567                     b = *s->bytestream++;
 568                     s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
 569                 }
 570                 for(;i<256;i++) {
 571                     s->palette[i] = (0xff << 24);
 572                 }
 573                 s->state |= PNG_PLTE;
 574                 crc = bytestream_get_be32(&s->bytestream);
 575             }
 576             break;
 577         case MKTAG('t', 'R', 'N', 'S'):
 578             {
 579                 int v, i;
 580
 581                 /* read the transparency. XXX: Only palette mode supported */
 582                 if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
 583                     length > 256 ||
 584                     !(s->state & PNG_PLTE))
 585                     goto skip_tag;
 586                 for(i=0;i<length;i++) {
 587                     v = *s->bytestream++;
 588                     s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
 589                 }
 590                 crc = bytestream_get_be32(&s->bytestream);
 591             }
 592             break;
 593         case MKTAG('I', 'E', 'N', 'D'):
 594             if (!(s->state & PNG_ALLIMAGE))
 595                 goto fail;
 596             crc = bytestream_get_be32(&s->bytestream);
 597             goto exit_loop;
 598         default:
 599             /* skip tag */
 600         skip_tag:
 601             s->bytestream += length + 4;
 602             break;
 603         }
 604     }
 605  exit_loop:
 606      /* handle p-frames only if a predecessor frame is available */
 607      if(s->last_picture->data[0] != NULL) {
 608          if(!(avpkt->flags & PKT_FLAG_KEY)) {
 609             int i, j;
 610             uint8_t *pd = s->current_picture->data[0];
 611             uint8_t *pd_last = s->last_picture->data[0];
 612
 613             for(j=0; j < s->height; j++) {
 614                 for(i=0; i < s->width * s->bpp; i++) {
 615                     pd[i] += pd_last[i];
 616                 }
 617                 pd += s->image_linesize;
 618                 pd_last += s->image_linesize;
 619             }
 620         }
 621     }
 622
 623     *picture= *s->current_picture;
 624     *data_size = sizeof(AVFrame);
 625
 626     ret = s->bytestream - s->bytestream_start;
 627  the_end:
 628     inflateEnd(&s->zstream);
 629     av_free(crow_buf_base);
 630     s->crow_buf = NULL;
 631     av_freep(&s->last_row);
 632     av_freep(&s->tmp_row);
 633     return ret;
 634  fail:
 635     ret = -1;
 636     goto the_end;
 637 }
 638
 639 static av_cold int png_dec_init(AVCodecContext *avctx){
 640     PNGDecContext *s = avctx->priv_data;
 641
 642     s->current_picture = &s->picture1;
 643     s->last_picture = &s->picture2;
 644     avcodec_get_frame_defaults(&s->picture1);
 645     avcodec_get_frame_defaults(&s->picture2);
 646     dsputil_init(&s->dsp, avctx);
 647
 648     return 0;
 649 }
 650
 651 AVCodec png_decoder = {
 652     "png",
 653     CODEC_TYPE_VIDEO,
 654     CODEC_ID_PNG,
 655     sizeof(PNGDecContext),
 656     png_dec_init,
 657     NULL,
 658     NULL, //decode_end,
 659     decode_frame,
 660     CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
 661     NULL,
 662     .long_name = NULL_IF_CONFIG_SMALL("PNG image"),
 663 };