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pngdec.c
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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 
22 //#define DEBUG
23 
24 #include "libavutil/bprint.h"
25 #include "libavutil/imgutils.h"
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "internal.h"
29 #include "png.h"
30 #include "pngdsp.h"
31 
32 /* TODO:
33  * - add 16 bit depth support
34  */
35 
36 #include <zlib.h>
37 
38 typedef struct PNGDecContext {
41 
44 
45  int state;
46  int width, height;
47  int bit_depth;
52  int channels;
54  int bpp;
55 
58  uint32_t palette[256];
62  int pass;
63  int crow_size; /* compressed row size (include filter type) */
64  int row_size; /* decompressed row size */
65  int pass_row_size; /* decompress row size of the current pass */
66  int y;
67  z_stream zstream;
69 
70 /* Mask to determine which pixels are valid in a pass */
71 static const uint8_t png_pass_mask[NB_PASSES] = {
72  0x01, 0x01, 0x11, 0x11, 0x55, 0x55, 0xff,
73 };
74 
75 /* Mask to determine which y pixels can be written in a pass */
77  0xff, 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
78 };
79 
80 /* Mask to determine which pixels to overwrite while displaying */
82  0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
83 };
84 
85 /* NOTE: we try to construct a good looking image at each pass. width
86  is the original image width. We also do pixel format conversion at
87  this stage */
88 static void png_put_interlaced_row(uint8_t *dst, int width,
89  int bits_per_pixel, int pass,
90  int color_type, const uint8_t *src)
91 {
92  int x, mask, dsp_mask, j, src_x, b, bpp;
93  uint8_t *d;
94  const uint8_t *s;
95 
96  mask = png_pass_mask[pass];
97  dsp_mask = png_pass_dsp_mask[pass];
98 
99  switch (bits_per_pixel) {
100  case 1:
101  src_x = 0;
102  for (x = 0; x < width; x++) {
103  j = (x & 7);
104  if ((dsp_mask << j) & 0x80) {
105  b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
106  dst[x >> 3] &= 0xFF7F>>j;
107  dst[x >> 3] |= b << (7 - j);
108  }
109  if ((mask << j) & 0x80)
110  src_x++;
111  }
112  break;
113  case 2:
114  src_x = 0;
115  for (x = 0; x < width; x++) {
116  int j2 = 2 * (x & 3);
117  j = (x & 7);
118  if ((dsp_mask << j) & 0x80) {
119  b = (src[src_x >> 2] >> (6 - 2*(src_x & 3))) & 3;
120  dst[x >> 2] &= 0xFF3F>>j2;
121  dst[x >> 2] |= b << (6 - j2);
122  }
123  if ((mask << j) & 0x80)
124  src_x++;
125  }
126  break;
127  case 4:
128  src_x = 0;
129  for (x = 0; x < width; x++) {
130  int j2 = 4*(x&1);
131  j = (x & 7);
132  if ((dsp_mask << j) & 0x80) {
133  b = (src[src_x >> 1] >> (4 - 4*(src_x & 1))) & 15;
134  dst[x >> 1] &= 0xFF0F>>j2;
135  dst[x >> 1] |= b << (4 - j2);
136  }
137  if ((mask << j) & 0x80)
138  src_x++;
139  }
140  break;
141  default:
142  bpp = bits_per_pixel >> 3;
143  d = dst;
144  s = src;
145  for (x = 0; x < width; x++) {
146  j = x & 7;
147  if ((dsp_mask << j) & 0x80) {
148  memcpy(d, s, bpp);
149  }
150  d += bpp;
151  if ((mask << j) & 0x80)
152  s += bpp;
153  }
154  break;
155  }
156 }
157 
158 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
159 {
160  int i;
161  for (i = 0; i < w; i++) {
162  int a, b, c, p, pa, pb, pc;
163 
164  a = dst[i - bpp];
165  b = top[i];
166  c = top[i - bpp];
167 
168  p = b - c;
169  pc = a - c;
170 
171  pa = abs(p);
172  pb = abs(pc);
173  pc = abs(p + pc);
174 
175  if (pa <= pb && pa <= pc)
176  p = a;
177  else if (pb <= pc)
178  p = b;
179  else
180  p = c;
181  dst[i] = p + src[i];
182  }
183 }
184 
185 #define UNROLL1(bpp, op) {\
186  r = dst[0];\
187  if(bpp >= 2) g = dst[1];\
188  if(bpp >= 3) b = dst[2];\
189  if(bpp >= 4) a = dst[3];\
190  for(; i <= size - bpp; i+=bpp) {\
191  dst[i+0] = r = op(r, src[i+0], last[i+0]);\
192  if(bpp == 1) continue;\
193  dst[i+1] = g = op(g, src[i+1], last[i+1]);\
194  if(bpp == 2) continue;\
195  dst[i+2] = b = op(b, src[i+2], last[i+2]);\
196  if(bpp == 3) continue;\
197  dst[i+3] = a = op(a, src[i+3], last[i+3]);\
198  }\
199 }
200 
201 #define UNROLL_FILTER(op)\
202  if(bpp == 1) UNROLL1(1, op)\
203  else if(bpp == 2) UNROLL1(2, op)\
204  else if(bpp == 3) UNROLL1(3, op)\
205  else if(bpp == 4) UNROLL1(4, op)\
206  for (; i < size; i++) {\
207  dst[i] = op(dst[i-bpp], src[i], last[i]);\
208  }\
209 
210 /* NOTE: 'dst' can be equal to 'last' */
211 static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
212  uint8_t *src, uint8_t *last, int size, int bpp)
213 {
214  int i, p, r, g, b, a;
215 
216  switch (filter_type) {
218  memcpy(dst, src, size);
219  break;
221  for (i = 0; i < bpp; i++) {
222  dst[i] = src[i];
223  }
224  if (bpp == 4) {
225  p = *(int*)dst;
226  for (; i < size; i += bpp) {
227  int s = *(int*)(src + i);
228  p = ((s & 0x7f7f7f7f) + (p & 0x7f7f7f7f)) ^ ((s ^ p) & 0x80808080);
229  *(int*)(dst + i) = p;
230  }
231  } else {
232 #define OP_SUB(x,s,l) x+s
234  }
235  break;
236  case PNG_FILTER_VALUE_UP:
237  dsp->add_bytes_l2(dst, src, last, size);
238  break;
240  for (i = 0; i < bpp; i++) {
241  p = (last[i] >> 1);
242  dst[i] = p + src[i];
243  }
244 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
246  break;
248  for (i = 0; i < bpp; i++) {
249  p = last[i];
250  dst[i] = p + src[i];
251  }
252  if (bpp > 2 && size > 4) {
253  // would write off the end of the array if we let it process the last pixel with bpp=3
254  int w = bpp == 4 ? size : size - 3;
255  dsp->add_paeth_prediction(dst + i, src + i, last + i, w - i, bpp);
256  i = w;
257  }
258  ff_add_png_paeth_prediction(dst + i, src + i, last + i, size - i, bpp);
259  break;
260  }
261 }
262 
263 /* This used to be called "deloco" in FFmpeg
264  * and is actually an inverse reversible colorspace transformation */
265 #define YUV2RGB(NAME, TYPE) \
266 static void deloco_ ## NAME(TYPE *dst, int size, int alpha) \
267 { \
268  int i; \
269  for (i = 0; i < size; i += 3 + alpha) { \
270  int g = dst [i+1]; \
271  dst[i+0] += g; \
272  dst[i+2] += g; \
273  } \
274 }
275 
276 YUV2RGB(rgb8, uint8_t)
277 YUV2RGB(rgb16, uint16_t)
278 
279 /* process exactly one decompressed row */
281 {
282  uint8_t *ptr, *last_row;
283  int got_line;
284 
285  if (!s->interlace_type) {
286  ptr = s->image_buf + s->image_linesize * s->y;
287  if (s->y == 0)
288  last_row = s->last_row;
289  else
290  last_row = ptr - s->image_linesize;
291 
292  png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
293  last_row, s->row_size, s->bpp);
294  /* loco lags by 1 row so that it doesn't interfere with top prediction */
295  if (s->filter_type == PNG_FILTER_TYPE_LOCO && s->y > 0) {
296  if (s->bit_depth == 16) {
297  deloco_rgb16((uint16_t *)(ptr - s->image_linesize), s->row_size / 2,
298  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
299  } else {
300  deloco_rgb8(ptr - s->image_linesize, s->row_size,
301  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
302  }
303  }
304  s->y++;
305  if (s->y == s->height) {
306  s->state |= PNG_ALLIMAGE;
307  if (s->filter_type == PNG_FILTER_TYPE_LOCO) {
308  if (s->bit_depth == 16) {
309  deloco_rgb16((uint16_t *)ptr, s->row_size / 2,
310  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
311  } else {
312  deloco_rgb8(ptr, s->row_size,
313  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
314  }
315  }
316  }
317  } else {
318  got_line = 0;
319  for (;;) {
320  ptr = s->image_buf + s->image_linesize * s->y;
321  if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
322  /* if we already read one row, it is time to stop to
323  wait for the next one */
324  if (got_line)
325  break;
326  png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
327  s->last_row, s->pass_row_size, s->bpp);
328  FFSWAP(uint8_t*, s->last_row, s->tmp_row);
329  got_line = 1;
330  }
331  if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
332  png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
333  s->color_type, s->last_row);
334  }
335  s->y++;
336  if (s->y == s->height) {
337  memset(s->last_row, 0, s->row_size);
338  for (;;) {
339  if (s->pass == NB_PASSES - 1) {
340  s->state |= PNG_ALLIMAGE;
341  goto the_end;
342  } else {
343  s->pass++;
344  s->y = 0;
345  s->pass_row_size = ff_png_pass_row_size(s->pass,
346  s->bits_per_pixel,
347  s->width);
348  s->crow_size = s->pass_row_size + 1;
349  if (s->pass_row_size != 0)
350  break;
351  /* skip pass if empty row */
352  }
353  }
354  }
355  }
356  the_end: ;
357  }
358 }
359 
361 {
362  int ret;
363  s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
364  s->zstream.next_in = (unsigned char *)s->gb.buffer;
365  bytestream2_skip(&s->gb, length);
366 
367  /* decode one line if possible */
368  while (s->zstream.avail_in > 0) {
369  ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
370  if (ret != Z_OK && ret != Z_STREAM_END) {
371  av_log(s->avctx, AV_LOG_ERROR, "inflate returned error %d\n", ret);
372  return AVERROR_EXTERNAL;
373  }
374  if (s->zstream.avail_out == 0) {
375  if (!(s->state & PNG_ALLIMAGE)) {
376  png_handle_row(s);
377  }
378  s->zstream.avail_out = s->crow_size;
379  s->zstream.next_out = s->crow_buf;
380  }
381  }
382  return 0;
383 }
384 
385 static int decode_zbuf(AVBPrint *bp, const uint8_t *data,
386  const uint8_t *data_end)
387 {
388  z_stream zstream;
389  unsigned char *buf;
390  unsigned buf_size;
391  int ret;
392 
393  zstream.zalloc = ff_png_zalloc;
394  zstream.zfree = ff_png_zfree;
395  zstream.opaque = NULL;
396  if (inflateInit(&zstream) != Z_OK)
397  return AVERROR_EXTERNAL;
398  zstream.next_in = (unsigned char *)data;
399  zstream.avail_in = data_end - data;
400  av_bprint_init(bp, 0, -1);
401 
402  while (zstream.avail_in > 0) {
403  av_bprint_get_buffer(bp, 1, &buf, &buf_size);
404  if (!buf_size) {
405  ret = AVERROR(ENOMEM);
406  goto fail;
407  }
408  zstream.next_out = buf;
409  zstream.avail_out = buf_size;
410  ret = inflate(&zstream, Z_PARTIAL_FLUSH);
411  if (ret != Z_OK && ret != Z_STREAM_END) {
412  ret = AVERROR_EXTERNAL;
413  goto fail;
414  }
415  bp->len += zstream.next_out - buf;
416  if (ret == Z_STREAM_END)
417  break;
418  }
419  inflateEnd(&zstream);
420  bp->str[bp->len] = 0;
421  return 0;
422 
423 fail:
424  inflateEnd(&zstream);
425  av_bprint_finalize(bp, NULL);
426  return ret;
427 }
428 
429 static uint8_t *iso88591_to_utf8(const uint8_t *in, size_t size_in)
430 {
431  size_t extra = 0, i;
432  uint8_t *out, *q;
433 
434  for (i = 0; i < size_in; i++)
435  extra += in[i] >= 0x80;
436  if (size_in == SIZE_MAX || extra > SIZE_MAX - size_in - 1)
437  return NULL;
438  q = out = av_malloc(size_in + extra + 1);
439  if (!out)
440  return NULL;
441  for (i = 0; i < size_in; i++) {
442  if (in[i] >= 0x80) {
443  *(q++) = 0xC0 | (in[i] >> 6);
444  *(q++) = 0x80 | (in[i] & 0x3F);
445  } else {
446  *(q++) = in[i];
447  }
448  }
449  *(q++) = 0;
450  return out;
451 }
452 
453 static int decode_text_chunk(PNGDecContext *s, uint32_t length, int compressed,
454  AVDictionary **dict)
455 {
456  int ret, method;
457  const uint8_t *data = s->gb.buffer;
458  const uint8_t *data_end = data + length;
459  const uint8_t *keyword = data;
460  const uint8_t *keyword_end = memchr(keyword, 0, data_end - keyword);
461  uint8_t *kw_utf8 = NULL, *text, *txt_utf8 = NULL;
462  unsigned text_len;
463  AVBPrint bp;
464 
465  if (!keyword_end)
466  return AVERROR_INVALIDDATA;
467  data = keyword_end + 1;
468 
469  if (compressed) {
470  if (data == data_end)
471  return AVERROR_INVALIDDATA;
472  method = *(data++);
473  if (method)
474  return AVERROR_INVALIDDATA;
475  if ((ret = decode_zbuf(&bp, data, data_end)) < 0)
476  return ret;
477  text_len = bp.len;
478  av_bprint_finalize(&bp, (char **)&text);
479  if (!text)
480  return AVERROR(ENOMEM);
481  } else {
482  text = (uint8_t *)data;
483  text_len = data_end - text;
484  }
485 
486  kw_utf8 = iso88591_to_utf8(keyword, keyword_end - keyword);
487  txt_utf8 = iso88591_to_utf8(text, text_len);
488  if (text != data)
489  av_free(text);
490  if (!(kw_utf8 && txt_utf8)) {
491  av_free(kw_utf8);
492  av_free(txt_utf8);
493  return AVERROR(ENOMEM);
494  }
495 
496  av_dict_set(dict, kw_utf8, txt_utf8,
498  return 0;
499 }
500 
501 static int decode_frame(AVCodecContext *avctx,
502  void *data, int *got_frame,
503  AVPacket *avpkt)
504 {
505  PNGDecContext * const s = avctx->priv_data;
506  const uint8_t *buf = avpkt->data;
507  int buf_size = avpkt->size;
508  AVFrame *p = data;
509  AVDictionary *metadata = NULL;
510  uint8_t *crow_buf_base = NULL;
511  uint32_t tag, length;
512  int64_t sig;
513  int ret;
514 
515  bytestream2_init(&s->gb, buf, buf_size);
516 
517  /* check signature */
518  sig = bytestream2_get_be64(&s->gb);
519  if (sig != PNGSIG &&
520  sig != MNGSIG) {
521  av_log(avctx, AV_LOG_ERROR, "Missing png signature\n");
522  return AVERROR_INVALIDDATA;
523  }
524 
525  s->y = s->state = 0;
526 
527  /* init the zlib */
528  s->zstream.zalloc = ff_png_zalloc;
529  s->zstream.zfree = ff_png_zfree;
530  s->zstream.opaque = NULL;
531  ret = inflateInit(&s->zstream);
532  if (ret != Z_OK) {
533  av_log(avctx, AV_LOG_ERROR, "inflateInit returned error %d\n", ret);
534  return AVERROR_EXTERNAL;
535  }
536  for (;;) {
537  if (bytestream2_get_bytes_left(&s->gb) <= 0) {
538  av_log(avctx, AV_LOG_ERROR, "No bytes left\n");
539  goto fail;
540  }
541 
542  length = bytestream2_get_be32(&s->gb);
543  if (length > 0x7fffffff || length > bytestream2_get_bytes_left(&s->gb)) {
544  av_log(avctx, AV_LOG_ERROR, "chunk too big\n");
545  goto fail;
546  }
547  tag = bytestream2_get_le32(&s->gb);
548  if (avctx->debug & FF_DEBUG_STARTCODE)
549  av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
550  (tag & 0xff),
551  ((tag >> 8) & 0xff),
552  ((tag >> 16) & 0xff),
553  ((tag >> 24) & 0xff), length);
554  switch (tag) {
555  case MKTAG('I', 'H', 'D', 'R'):
556  if (length != 13)
557  goto fail;
558  s->width = bytestream2_get_be32(&s->gb);
559  s->height = bytestream2_get_be32(&s->gb);
560  if (av_image_check_size(s->width, s->height, 0, avctx)) {
561  s->width = s->height = 0;
562  av_log(avctx, AV_LOG_ERROR, "Invalid image size\n");
563  goto fail;
564  }
565  s->bit_depth = bytestream2_get_byte(&s->gb);
566  s->color_type = bytestream2_get_byte(&s->gb);
567  s->compression_type = bytestream2_get_byte(&s->gb);
568  s->filter_type = bytestream2_get_byte(&s->gb);
569  s->interlace_type = bytestream2_get_byte(&s->gb);
570  bytestream2_skip(&s->gb, 4); /* crc */
571  s->state |= PNG_IHDR;
572  if (avctx->debug & FF_DEBUG_PICT_INFO)
573  av_log(avctx, AV_LOG_DEBUG, "width=%d height=%d depth=%d color_type=%d "
574  "compression_type=%d filter_type=%d interlace_type=%d\n",
575  s->width, s->height, s->bit_depth, s->color_type,
577  break;
578  case MKTAG('p', 'H', 'Y', 's'):
579  if (s->state & PNG_IDAT) {
580  av_log(avctx, AV_LOG_ERROR, "pHYs after IDAT\n");
581  goto fail;
582  }
583  avctx->sample_aspect_ratio.num = bytestream2_get_be32(&s->gb);
584  avctx->sample_aspect_ratio.den = bytestream2_get_be32(&s->gb);
585  if (avctx->sample_aspect_ratio.num < 0 || avctx->sample_aspect_ratio.den < 0)
586  avctx->sample_aspect_ratio = (AVRational){ 0, 1 };
587  bytestream2_skip(&s->gb, 1); /* unit specifier */
588  bytestream2_skip(&s->gb, 4); /* crc */
589  break;
590  case MKTAG('I', 'D', 'A', 'T'):
591  if (!(s->state & PNG_IHDR)) {
592  av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
593  goto fail;
594  }
595  if (!(s->state & PNG_IDAT)) {
596  /* init image info */
597  avctx->width = s->width;
598  avctx->height = s->height;
599 
601  s->bits_per_pixel = s->bit_depth * s->channels;
602  s->bpp = (s->bits_per_pixel + 7) >> 3;
603  s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
604 
605  if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
607  avctx->pix_fmt = AV_PIX_FMT_RGB24;
608  } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
610  avctx->pix_fmt = AV_PIX_FMT_RGBA;
611  } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
613  avctx->pix_fmt = AV_PIX_FMT_GRAY8;
614  } else if (s->bit_depth == 16 &&
616  avctx->pix_fmt = AV_PIX_FMT_GRAY16BE;
617  } else if (s->bit_depth == 16 &&
619  avctx->pix_fmt = AV_PIX_FMT_RGB48BE;
620  } else if (s->bit_depth == 16 &&
622  avctx->pix_fmt = AV_PIX_FMT_RGBA64BE;
623  } else if ((s->bits_per_pixel == 1 || s->bits_per_pixel == 2 || s->bits_per_pixel == 4 || s->bits_per_pixel == 8) &&
625  avctx->pix_fmt = AV_PIX_FMT_PAL8;
626  } else if (s->bit_depth == 1) {
627  avctx->pix_fmt = AV_PIX_FMT_MONOBLACK;
628  } else if (s->bit_depth == 8 &&
630  avctx->pix_fmt = AV_PIX_FMT_Y400A;
631  } else {
632  av_log(avctx, AV_LOG_ERROR, "unsupported bit depth %d "
633  "and color type %d\n",
634  s->bit_depth, s->color_type);
635  goto fail;
636  }
637 
638  if (ff_get_buffer(avctx, p, AV_GET_BUFFER_FLAG_REF) < 0)
639  goto fail;
641  p->key_frame = 1;
643 
644  /* compute the compressed row size */
645  if (!s->interlace_type) {
646  s->crow_size = s->row_size + 1;
647  } else {
648  s->pass = 0;
650  s->bits_per_pixel,
651  s->width);
652  s->crow_size = s->pass_row_size + 1;
653  }
654  av_dlog(avctx, "row_size=%d crow_size =%d\n",
655  s->row_size, s->crow_size);
656  s->image_buf = p->data[0];
657  s->image_linesize = p->linesize[0];
658  /* copy the palette if needed */
659  if (avctx->pix_fmt == AV_PIX_FMT_PAL8)
660  memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
661  /* empty row is used if differencing to the first row */
662  s->last_row = av_mallocz(s->row_size);
663  if (!s->last_row)
664  goto fail;
665  if (s->interlace_type ||
667  s->tmp_row = av_malloc(s->row_size);
668  if (!s->tmp_row)
669  goto fail;
670  }
671  /* compressed row */
672  crow_buf_base = av_malloc(s->row_size + 16);
673  if (!crow_buf_base)
674  goto fail;
675 
676  /* we want crow_buf+1 to be 16-byte aligned */
677  s->crow_buf = crow_buf_base + 15;
678  s->zstream.avail_out = s->crow_size;
679  s->zstream.next_out = s->crow_buf;
680  }
681  s->state |= PNG_IDAT;
682  if (png_decode_idat(s, length) < 0)
683  goto fail;
684  bytestream2_skip(&s->gb, 4); /* crc */
685  break;
686  case MKTAG('P', 'L', 'T', 'E'):
687  {
688  int n, i, r, g, b;
689 
690  if ((length % 3) != 0 || length > 256 * 3)
691  goto skip_tag;
692  /* read the palette */
693  n = length / 3;
694  for (i = 0; i < n; i++) {
695  r = bytestream2_get_byte(&s->gb);
696  g = bytestream2_get_byte(&s->gb);
697  b = bytestream2_get_byte(&s->gb);
698  s->palette[i] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
699  }
700  for (; i < 256; i++) {
701  s->palette[i] = (0xFFU << 24);
702  }
703  s->state |= PNG_PLTE;
704  bytestream2_skip(&s->gb, 4); /* crc */
705  }
706  break;
707  case MKTAG('t', 'R', 'N', 'S'):
708  {
709  int v, i;
710 
711  /* read the transparency. XXX: Only palette mode supported */
713  length > 256 ||
714  !(s->state & PNG_PLTE))
715  goto skip_tag;
716  for (i = 0; i < length; i++) {
717  v = bytestream2_get_byte(&s->gb);
718  s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
719  }
720  bytestream2_skip(&s->gb, 4); /* crc */
721  }
722  break;
723  case MKTAG('t', 'E', 'X', 't'):
724  if (decode_text_chunk(s, length, 0, &metadata) < 0)
725  av_log(avctx, AV_LOG_WARNING, "Broken tEXt chunk\n");
726  bytestream2_skip(&s->gb, length + 4);
727  break;
728  case MKTAG('z', 'T', 'X', 't'):
729  if (decode_text_chunk(s, length, 1, &metadata) < 0)
730  av_log(avctx, AV_LOG_WARNING, "Broken zTXt chunk\n");
731  bytestream2_skip(&s->gb, length + 4);
732  break;
733  case MKTAG('I', 'E', 'N', 'D'):
734  if (!(s->state & PNG_ALLIMAGE))
735  av_log(avctx, AV_LOG_ERROR, "IEND without all image\n");
736  if (!(s->state & (PNG_ALLIMAGE|PNG_IDAT))) {
737  goto fail;
738  }
739  bytestream2_skip(&s->gb, 4); /* crc */
740  goto exit_loop;
741  default:
742  /* skip tag */
743  skip_tag:
744  bytestream2_skip(&s->gb, length + 4);
745  break;
746  }
747  }
748  exit_loop:
749 
750  if (s->bits_per_pixel == 1 && s->color_type == PNG_COLOR_TYPE_PALETTE){
751  int i, j, k;
752  uint8_t *pd = p->data[0];
753  for (j = 0; j < s->height; j++) {
754  i = s->width / 8;
755  for (k = 7; k >= 1; k--)
756  if ((s->width&7) >= k)
757  pd[8*i + k - 1] = (pd[i]>>8-k) & 1;
758  for (i--; i >= 0; i--) {
759  pd[8*i + 7]= pd[i] & 1;
760  pd[8*i + 6]= (pd[i]>>1) & 1;
761  pd[8*i + 5]= (pd[i]>>2) & 1;
762  pd[8*i + 4]= (pd[i]>>3) & 1;
763  pd[8*i + 3]= (pd[i]>>4) & 1;
764  pd[8*i + 2]= (pd[i]>>5) & 1;
765  pd[8*i + 1]= (pd[i]>>6) & 1;
766  pd[8*i + 0]= pd[i]>>7;
767  }
768  pd += s->image_linesize;
769  }
770  }
771  if (s->bits_per_pixel == 2){
772  int i, j;
773  uint8_t *pd = p->data[0];
774  for (j = 0; j < s->height; j++) {
775  i = s->width / 4;
777  if ((s->width&3) >= 3) pd[4*i + 2]= (pd[i] >> 2) & 3;
778  if ((s->width&3) >= 2) pd[4*i + 1]= (pd[i] >> 4) & 3;
779  if ((s->width&3) >= 1) pd[4*i + 0]= pd[i] >> 6;
780  for (i--; i >= 0; i--) {
781  pd[4*i + 3]= pd[i] & 3;
782  pd[4*i + 2]= (pd[i]>>2) & 3;
783  pd[4*i + 1]= (pd[i]>>4) & 3;
784  pd[4*i + 0]= pd[i]>>6;
785  }
786  } else {
787  if ((s->width&3) >= 3) pd[4*i + 2]= ((pd[i]>>2) & 3)*0x55;
788  if ((s->width&3) >= 2) pd[4*i + 1]= ((pd[i]>>4) & 3)*0x55;
789  if ((s->width&3) >= 1) pd[4*i + 0]= ( pd[i]>>6 )*0x55;
790  for (i--; i >= 0; i--) {
791  pd[4*i + 3]= ( pd[i] & 3)*0x55;
792  pd[4*i + 2]= ((pd[i]>>2) & 3)*0x55;
793  pd[4*i + 1]= ((pd[i]>>4) & 3)*0x55;
794  pd[4*i + 0]= ( pd[i]>>6 )*0x55;
795  }
796  }
797  pd += s->image_linesize;
798  }
799  }
800  if (s->bits_per_pixel == 4){
801  int i, j;
802  uint8_t *pd = p->data[0];
803  for (j = 0; j < s->height; j++) {
804  i = s->width/2;
806  if (s->width&1) pd[2*i+0]= pd[i]>>4;
807  for (i--; i >= 0; i--) {
808  pd[2*i + 1] = pd[i] & 15;
809  pd[2*i + 0] = pd[i] >> 4;
810  }
811  } else {
812  if (s->width & 1) pd[2*i + 0]= (pd[i] >> 4) * 0x11;
813  for (i--; i >= 0; i--) {
814  pd[2*i + 1] = (pd[i] & 15) * 0x11;
815  pd[2*i + 0] = (pd[i] >> 4) * 0x11;
816  }
817  }
818  pd += s->image_linesize;
819  }
820  }
821 
822  /* handle p-frames only if a predecessor frame is available */
823  if (s->prev->data[0]) {
824  if ( !(avpkt->flags & AV_PKT_FLAG_KEY) && avctx->codec_tag != AV_RL32("MPNG")
825  && s->prev->width == p->width
826  && s->prev->height== p->height
827  && s->prev->format== p->format
828  ) {
829  int i, j;
830  uint8_t *pd = p->data[0];
831  uint8_t *pd_last = s->prev->data[0];
832 
833  for (j = 0; j < s->height; j++) {
834  for (i = 0; i < s->width * s->bpp; i++) {
835  pd[i] += pd_last[i];
836  }
837  pd += s->image_linesize;
838  pd_last += s->image_linesize;
839  }
840  }
841  }
842 
843  av_frame_set_metadata(p, metadata);
844  metadata = NULL;
845 
846  av_frame_unref(s->prev);
847  if ((ret = av_frame_ref(s->prev, p)) < 0)
848  goto fail;
849 
850  *got_frame = 1;
851 
852  ret = bytestream2_tell(&s->gb);
853  the_end:
854  inflateEnd(&s->zstream);
855  av_free(crow_buf_base);
856  s->crow_buf = NULL;
857  av_freep(&s->last_row);
858  av_freep(&s->tmp_row);
859  return ret;
860  fail:
861  av_dict_free(&metadata);
862  ret = AVERROR_INVALIDDATA;
863  goto the_end;
864 }
865 
867 {
868  PNGDecContext *s = avctx->priv_data;
869 
870  s->prev = av_frame_alloc();
871  if (!s->prev)
872  return AVERROR(ENOMEM);
873 
874  ff_pngdsp_init(&s->dsp);
875 
876  s->avctx = avctx;
877 
878  return 0;
879 }
880 
882 {
883  PNGDecContext *s = avctx->priv_data;
884 
885  av_frame_free(&s->prev);
886 
887  return 0;
888 }
889 
891  .name = "png",
892  .type = AVMEDIA_TYPE_VIDEO,
893  .id = AV_CODEC_ID_PNG,
894  .priv_data_size = sizeof(PNGDecContext),
895  .init = png_dec_init,
896  .close = png_dec_end,
897  .decode = decode_frame,
898  .capabilities = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
899  .long_name = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
900 };