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
 185 /* NOTE: 'dst' can be equal to 'last' */
 186 static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
 187                            uint8_t *src, uint8_t *last, int size, int bpp)
 188 {
 189     int i, p, r, g, b, a;
 190
 191     switch(filter_type) {
 192     case PNG_FILTER_VALUE_NONE:
 193         memcpy(dst, src, size);
 194         break;
 195     case PNG_FILTER_VALUE_SUB:
 196         for(i = 0; i < bpp; i++) {
 197             dst[i] = src[i];
 198         }
 199         if(bpp == 4) {
 200             p = *(int*)dst;
 201             for(; i < size; i+=bpp) {
 202                 int s = *(int*)(src+i);
 203                 p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
 204                 *(int*)(dst+i) = p;
 205             }
 206         } else {
 207 #define OP_SUB(x,s,l) x+s
 208             UNROLL_FILTER(OP_SUB);
 209         }
 210         break;
 211     case PNG_FILTER_VALUE_UP:
 212         dsp->add_bytes_l2(dst, src, last, size);
 213         break;
 214     case PNG_FILTER_VALUE_AVG:
 215         for(i = 0; i < bpp; i++) {
 216             p = (last[i] >> 1);
 217             dst[i] = p + src[i];
 218         }
 219 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
 220         UNROLL_FILTER(OP_AVG);
 221         break;
 222     case PNG_FILTER_VALUE_PAETH:
 223         for(i = 0; i < bpp; i++) {
 224             p = last[i];
 225             dst[i] = p + src[i];
 226         }
 227         if(bpp > 1 && size > 4) {
 228             // would write off the end of the array if we let it process the last pixel with bpp=3
 229             int w = bpp==4 ? size : size-3;
 230             dsp->add_png_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
 231             i = w;
 232         }
 233         ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
 234         break;
 235     }
 236 }
 237
 238 static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
 239 {
 240     int j;
 241     unsigned int r, g, b, a;
 242
 243     for(j = 0;j < width; j++) {
 244         r = src[0];
 245         g = src[1];
 246         b = src[2];
 247         a = src[3];
 248         if(loco) {
 249             r = (r+g)&0xff;
 250             b = (b+g)&0xff;
 251         }
 252         *(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
 253         dst += 4;
 254         src += 4;
 255     }
 256 }
 257
 258 static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
 259 {
 260     if(loco)
 261         convert_to_rgb32_loco(dst, src, width, 1);
 262     else
 263         convert_to_rgb32_loco(dst, src, width, 0);
 264 }
 265
 266 static void deloco_rgb24(uint8_t *dst, int size)
 267 {
 268     int i;
 269     for(i=0; i<size; i+=3) {
 270         int g = dst[i+1];
 271         dst[i+0] += g;
 272         dst[i+2] += g;
 273     }
 274 }
 275
 276 /* process exactly one decompressed row */
 277 static void png_handle_row(PNGDecContext *s)
 278 {
 279     uint8_t *ptr, *last_row;
 280     int got_line;
 281
 282     if (!s->interlace_type) {
 283         ptr = s->image_buf + s->image_linesize * s->y;
 284         /* need to swap bytes correctly for RGB_ALPHA */
 285         if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 286             png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 287                            s->last_row, s->row_size, s->bpp);
 288             convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
 289             FFSWAP(uint8_t*, s->last_row, s->tmp_row);
 290         } else {
 291             /* in normal case, we avoid one copy */
 292             if (s->y == 0)
 293                 last_row = s->last_row;
 294             else
 295                 last_row = ptr - s->image_linesize;
 296
 297             png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
 298                            last_row, s->row_size, s->bpp);
 299         }
 300         /* loco lags by 1 row so that it doesn't interfere with top prediction */
 301         if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
 302             s->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
 303             deloco_rgb24(ptr - s->image_linesize, s->row_size);
 304         s->y++;
 305         if (s->y == s->height) {
 306             s->state |= PNG_ALLIMAGE;
 307             if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
 308                 s->color_type == PNG_COLOR_TYPE_RGB)
 309                 deloco_rgb24(ptr, s->row_size);
 310         }
 311     } else {
 312         got_line = 0;
 313         for(;;) {
 314             ptr = s->image_buf + s->image_linesize * s->y;
 315             if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
 316                 /* if we already read one row, it is time to stop to
 317                    wait for the next one */
 318                 if (got_line)
 319                     break;
 320                 png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
 321                                s->last_row, s->pass_row_size, s->bpp);
 322                 FFSWAP(uint8_t*, s->last_row, s->tmp_row);
 323                 got_line = 1;
 324             }
 325             if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
 326                 /* NOTE: RGB32 is handled directly in png_put_interlaced_row */
 327                 png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
 328                                        s->color_type, s->last_row);
 329             }
 330             s->y++;
 331             if (s->y == s->height) {
 332                 for(;;) {
 333                     if (s->pass == NB_PASSES - 1) {
 334                         s->state |= PNG_ALLIMAGE;
 335                         goto the_end;
 336                     } else {
 337                         s->pass++;
 338                         s->y = 0;
 339                         s->pass_row_size = ff_png_pass_row_size(s->pass,
 340                                                              s->bits_per_pixel,
 341                                                              s->width);
 342                         s->crow_size = s->pass_row_size + 1;
 343                         if (s->pass_row_size != 0)
 344                             break;
 345                         /* skip pass if empty row */
 346                     }
 347                 }
 348             }
 349         }
 350     the_end: ;
 351     }
 352 }
 353
 354 static int png_decode_idat(PNGDecContext *s, int length)
 355 {
 356     int ret;
 357     s->zstream.avail_in = length;
 358     s->zstream.next_in = s->bytestream;
 359     s->bytestream += length;
 360
 361     if(s->bytestream > s->bytestream_end)
 362         return -1;
 363
 364     /* decode one line if possible */
 365     while (s->zstream.avail_in > 0) {
 366         ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
 367         if (ret != Z_OK && ret != Z_STREAM_END) {
 368             return -1;
 369         }
 370         if (s->zstream.avail_out == 0) {
 371             if (!(s->state & PNG_ALLIMAGE)) {
 372                 png_handle_row(s);
 373             }
 374             s->zstream.avail_out = s->crow_size;
 375             s->zstream.next_out = s->crow_buf;
 376         }
 377     }
 378     return 0;
 379 }
 380
 381 static int decode_frame(AVCodecContext *avctx,
 382                         void *data, int *data_size,
 383                         AVPacket *avpkt)
 384 {
 385     const uint8_t *buf = avpkt->data;
 386     int buf_size = avpkt->size;
 387     PNGDecContext * const s = avctx->priv_data;
 388     AVFrame *picture = data;
 389     AVFrame *p;
 390     uint8_t *crow_buf_base = NULL;
 391     uint32_t tag, length;
 392     int ret, crc;
 393
 394     FFSWAP(AVFrame *, s->current_picture, s->last_picture);
 395     avctx->coded_frame= s->current_picture;
 396     p = s->current_picture;
 397
 398     s->bytestream_start=
 399     s->bytestream= buf;
 400     s->bytestream_end= buf + buf_size;
 401
 402     /* check signature */
 403     if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&
 404         memcmp(s->bytestream, ff_mngsig, 8) != 0)
 405         return -1;
 406     s->bytestream+= 8;
 407     s->y=
 408     s->state=0;
 409 //    memset(s, 0, sizeof(PNGDecContext));
 410     /* init the zlib */
 411     s->zstream.zalloc = ff_png_zalloc;
 412     s->zstream.zfree = ff_png_zfree;
 413     s->zstream.opaque = NULL;
 414     ret = inflateInit(&s->zstream);
 415     if (ret != Z_OK)
 416         return -1;
 417     for(;;) {
 418         int tag32;
 419         if (s->bytestream >= s->bytestream_end)
 420             goto fail;
 421         length = bytestream_get_be32(&s->bytestream);
 422         if (length > 0x7fffffff)
 423             goto fail;
 424         tag32 = bytestream_get_be32(&s->bytestream);
 425         tag = bswap_32(tag32);
 426 #ifdef DEBUG
 427         av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
 428                (tag & 0xff),
 429                ((tag >> 8) & 0xff),
 430                ((tag >> 16) & 0xff),
 431                ((tag >> 24) & 0xff), length);
 432 #endif
 433         switch(tag) {
 434         case MKTAG('I', 'H', 'D', 'R'):
 435             if (length != 13)
 436                 goto fail;
 437             s->width = bytestream_get_be32(&s->bytestream);
 438             s->height = bytestream_get_be32(&s->bytestream);
 439             if(avcodec_check_dimensions(avctx, s->width, s->height)){
 440                 s->width= s->height= 0;
 441                 goto fail;
 442             }
 443             s->bit_depth = *s->bytestream++;
 444             s->color_type = *s->bytestream++;
 445             s->compression_type = *s->bytestream++;
 446             s->filter_type = *s->bytestream++;
 447             s->interlace_type = *s->bytestream++;
 448             crc = bytestream_get_be32(&s->bytestream);
 449             s->state |= PNG_IHDR;
 450 #ifdef DEBUG
 451             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",
 452                    s->width, s->height, s->bit_depth, s->color_type,
 453                    s->compression_type, s->filter_type, s->interlace_type);
 454 #endif
 455             break;
 456         case MKTAG('I', 'D', 'A', 'T'):
 457             if (!(s->state & PNG_IHDR))
 458                 goto fail;
 459             if (!(s->state & PNG_IDAT)) {
 460                 /* init image info */
 461                 avctx->width = s->width;
 462                 avctx->height = s->height;
 463
 464                 s->channels = ff_png_get_nb_channels(s->color_type);
 465                 s->bits_per_pixel = s->bit_depth * s->channels;
 466                 s->bpp = (s->bits_per_pixel + 7) >> 3;
 467                 s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
 468
 469                 if (s->bit_depth == 8 &&
 470                     s->color_type == PNG_COLOR_TYPE_RGB) {
 471                     avctx->pix_fmt = PIX_FMT_RGB24;
 472                 } else if (s->bit_depth == 8 &&
 473                            s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 474                     avctx->pix_fmt = PIX_FMT_RGB32;
 475                 } else if (s->bit_depth == 8 &&
 476                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 477                     avctx->pix_fmt = PIX_FMT_GRAY8;
 478                 } else if (s->bit_depth == 16 &&
 479                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 480                     avctx->pix_fmt = PIX_FMT_GRAY16BE;
 481                 } else if (s->bit_depth == 1 &&
 482                            s->color_type == PNG_COLOR_TYPE_GRAY) {
 483                     avctx->pix_fmt = PIX_FMT_MONOBLACK;
 484                 } else if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
 485                     avctx->pix_fmt = PIX_FMT_PAL8;
 486                 } else {
 487                     goto fail;
 488                 }
 489                 if(p->data[0])
 490                     avctx->release_buffer(avctx, p);
 491
 492                 p->reference= 0;
 493                 if(avctx->get_buffer(avctx, p) < 0){
 494                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 495                     goto fail;
 496                 }
 497                 p->pict_type= FF_I_TYPE;
 498                 p->key_frame= 1;
 499                 p->interlaced_frame = !!s->interlace_type;
 500
 501                 /* compute the compressed row size */
 502                 if (!s->interlace_type) {
 503                     s->crow_size = s->row_size + 1;
 504                 } else {
 505                     s->pass = 0;
 506                     s->pass_row_size = ff_png_pass_row_size(s->pass,
 507                                                          s->bits_per_pixel,
 508                                                          s->width);
 509                     s->crow_size = s->pass_row_size + 1;
 510                 }
 511 #ifdef DEBUG
 512                 av_log(avctx, AV_LOG_DEBUG, "row_size=%d crow_size =%d\n",
 513                        s->row_size, s->crow_size);
 514 #endif
 515                 s->image_buf = p->data[0];
 516                 s->image_linesize = p->linesize[0];
 517                 /* copy the palette if needed */
 518                 if (s->color_type == PNG_COLOR_TYPE_PALETTE)
 519                     memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
 520                 /* empty row is used if differencing to the first row */
 521                 s->last_row = av_mallocz(s->row_size);
 522                 if (!s->last_row)
 523                     goto fail;
 524                 if (s->interlace_type ||
 525                     s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
 526                     s->tmp_row = av_malloc(s->row_size);
 527                     if (!s->tmp_row)
 528                         goto fail;
 529                 }
 530                 /* compressed row */
 531                 crow_buf_base = av_malloc(s->row_size + 16);
 532                 if (!crow_buf_base)
 533                     goto fail;
 534
 535                 /* we want crow_buf+1 to be 16-byte aligned */
 536                 s->crow_buf = crow_buf_base + 15;
 537                 s->zstream.avail_out = s->crow_size;
 538                 s->zstream.next_out = s->crow_buf;
 539             }
 540             s->state |= PNG_IDAT;
 541             if (png_decode_idat(s, length) < 0)
 542                 goto fail;
 543             /* skip crc */
 544             crc = bytestream_get_be32(&s->bytestream);
 545             break;
 546         case MKTAG('P', 'L', 'T', 'E'):
 547             {
 548                 int n, i, r, g, b;
 549
 550                 if ((length % 3) != 0 || length > 256 * 3)
 551                     goto skip_tag;
 552                 /* read the palette */
 553                 n = length / 3;
 554                 for(i=0;i<n;i++) {
 555                     r = *s->bytestream++;
 556                     g = *s->bytestream++;
 557                     b = *s->bytestream++;
 558                     s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
 559                 }
 560                 for(;i<256;i++) {
 561                     s->palette[i] = (0xff << 24);
 562                 }
 563                 s->state |= PNG_PLTE;
 564                 crc = bytestream_get_be32(&s->bytestream);
 565             }
 566             break;
 567         case MKTAG('t', 'R', 'N', 'S'):
 568             {
 569                 int v, i;
 570
 571                 /* read the transparency. XXX: Only palette mode supported */
 572                 if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
 573                     length > 256 ||
 574                     !(s->state & PNG_PLTE))
 575                     goto skip_tag;
 576                 for(i=0;i<length;i++) {
 577                     v = *s->bytestream++;
 578                     s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
 579                 }
 580                 crc = bytestream_get_be32(&s->bytestream);
 581             }
 582             break;
 583         case MKTAG('I', 'E', 'N', 'D'):
 584             if (!(s->state & PNG_ALLIMAGE))
 585                 goto fail;
 586             crc = bytestream_get_be32(&s->bytestream);
 587             goto exit_loop;
 588         default:
 589             /* skip tag */
 590         skip_tag:
 591             s->bytestream += length + 4;
 592             break;
 593         }
 594     }
 595  exit_loop:
 596      /* handle p-frames only if a predecessor frame is available */
 597      if(s->last_picture->data[0] != NULL) {
 598          if(!(avpkt->flags & PKT_FLAG_KEY)) {
 599             int i, j;
 600             uint8_t *pd = s->current_picture->data[0];
 601             uint8_t *pd_last = s->last_picture->data[0];
 602
 603             for(j=0; j < s->height; j++) {
 604                 for(i=0; i < s->width * s->bpp; i++) {
 605                     pd[i] += pd_last[i];
 606                 }
 607                 pd += s->image_linesize;
 608                 pd_last += s->image_linesize;
 609             }
 610         }
 611     }
 612
 613     *picture= *s->current_picture;
 614     *data_size = sizeof(AVFrame);
 615
 616     ret = s->bytestream - s->bytestream_start;
 617  the_end:
 618     inflateEnd(&s->zstream);
 619     av_free(crow_buf_base);
 620     s->crow_buf = NULL;
 621     av_freep(&s->last_row);
 622     av_freep(&s->tmp_row);
 623     return ret;
 624  fail:
 625     ret = -1;
 626     goto the_end;
 627 }
 628
 629 static av_cold int png_dec_init(AVCodecContext *avctx){
 630     PNGDecContext *s = avctx->priv_data;
 631
 632     s->current_picture = &s->picture1;
 633     s->last_picture = &s->picture2;
 634     avcodec_get_frame_defaults(&s->picture1);
 635     avcodec_get_frame_defaults(&s->picture2);
 636     dsputil_init(&s->dsp, avctx);
 637
 638     return 0;
 639 }
 640
 641 AVCodec png_decoder = {
 642     "png",
 643     CODEC_TYPE_VIDEO,
 644     CODEC_ID_PNG,
 645     sizeof(PNGDecContext),
 646     png_dec_init,
 647     NULL,
 648     NULL, //decode_end,
 649     decode_frame,
 650     CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
 651     NULL,
 652     .long_name = NULL_IF_CONFIG_SMALL("PNG image"),
 653 };