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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 //#define DEBUG
39 
40 typedef struct PNGDecContext {
41  PNGDSPContext dsp;
42  AVCodecContext *avctx;
43 
44  GetByteContext gb;
45  AVFrame picture1, picture2;
46  AVFrame *current_picture, *last_picture;
47 
48  int state;
49  int width, height;
50  int bit_depth;
51  int color_type;
52  int compression_type;
53  int interlace_type;
54  int filter_type;
55  int channels;
56  int bits_per_pixel;
57  int bpp;
58 
59  uint8_t *image_buf;
60  int image_linesize;
61  uint32_t palette[256];
62  uint8_t *crow_buf;
63  uint8_t *last_row;
64  uint8_t *tmp_row;
65  int pass;
66  int crow_size; /* compressed row size (include filter type) */
67  int row_size; /* decompressed row size */
68  int pass_row_size; /* decompress row size of the current pass */
69  int y;
70  z_stream zstream;
71 } PNGDecContext;
72 
73 /* Mask to determine which pixels are valid in a pass */
74 static const uint8_t png_pass_mask[NB_PASSES] = {
75  0x01, 0x01, 0x11, 0x11, 0x55, 0x55, 0xff,
76 };
77 
78 /* Mask to determine which y pixels can be written in a pass */
79 static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
80  0xff, 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
81 };
82 
83 /* Mask to determine which pixels to overwrite while displaying */
84 static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
85  0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
86 };
87 
88 /* NOTE: we try to construct a good looking image at each pass. width
89  is the original image width. We also do pixel format conversion at
90  this stage */
91 static void png_put_interlaced_row(uint8_t *dst, int width,
92  int bits_per_pixel, int pass,
93  int color_type, const uint8_t *src)
94 {
95  int x, mask, dsp_mask, j, src_x, b, bpp;
96  uint8_t *d;
97  const uint8_t *s;
98 
99  mask = png_pass_mask[pass];
100  dsp_mask = png_pass_dsp_mask[pass];
101  switch(bits_per_pixel) {
102  case 1:
103  src_x = 0;
104  for(x = 0; x < width; x++) {
105  j = (x & 7);
106  if ((dsp_mask << j) & 0x80) {
107  b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
108  dst[x >> 3] &= 0xFF7F>>j;
109  dst[x >> 3] |= b << (7 - j);
110  }
111  if ((mask << j) & 0x80)
112  src_x++;
113  }
114  break;
115  case 2:
116  src_x = 0;
117  for(x = 0; x < width; x++) {
118  int j2 = 2*(x&3);
119  j = (x & 7);
120  if ((dsp_mask << j) & 0x80) {
121  b = (src[src_x >> 2] >> (6 - 2*(src_x & 3))) & 3;
122  dst[x >> 2] &= 0xFF3F>>j2;
123  dst[x >> 2] |= b << (6 - j2);
124  }
125  if ((mask << j) & 0x80)
126  src_x++;
127  }
128  break;
129  case 4:
130  src_x = 0;
131  for(x = 0; x < width; x++) {
132  int j2 = 4*(x&1);
133  j = (x & 7);
134  if ((dsp_mask << j) & 0x80) {
135  b = (src[src_x >> 1] >> (4 - 4*(src_x & 1))) & 15;
136  dst[x >> 1] &= 0xFF0F>>j2;
137  dst[x >> 1] |= b << (4 - j2);
138  }
139  if ((mask << j) & 0x80)
140  src_x++;
141  }
142  break;
143  default:
144  bpp = bits_per_pixel >> 3;
145  d = dst;
146  s = src;
147  for(x = 0; x < width; x++) {
148  j = x & 7;
149  if ((dsp_mask << j) & 0x80) {
150  memcpy(d, s, bpp);
151  }
152  d += bpp;
153  if ((mask << j) & 0x80)
154  s += bpp;
155  }
156  break;
157  }
158 }
159 
160 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
161 {
162  int i;
163  for(i = 0; i < w; i++) {
164  int a, b, c, p, pa, pb, pc;
165 
166  a = dst[i - bpp];
167  b = top[i];
168  c = top[i - bpp];
169 
170  p = b - c;
171  pc = a - c;
172 
173  pa = abs(p);
174  pb = abs(pc);
175  pc = abs(p + pc);
176 
177  if (pa <= pb && pa <= pc)
178  p = a;
179  else if (pb <= pc)
180  p = b;
181  else
182  p = c;
183  dst[i] = p + src[i];
184  }
185 }
186 
187 #define UNROLL1(bpp, op) {\
188  r = dst[0];\
189  if(bpp >= 2) g = dst[1];\
190  if(bpp >= 3) b = dst[2];\
191  if(bpp >= 4) a = dst[3];\
192  for(; i <= size - bpp; i+=bpp) {\
193  dst[i+0] = r = op(r, src[i+0], last[i+0]);\
194  if(bpp == 1) continue;\
195  dst[i+1] = g = op(g, src[i+1], last[i+1]);\
196  if(bpp == 2) continue;\
197  dst[i+2] = b = op(b, src[i+2], last[i+2]);\
198  if(bpp == 3) continue;\
199  dst[i+3] = a = op(a, src[i+3], last[i+3]);\
200  }\
201 }
202 
203 #define UNROLL_FILTER(op)\
204  if(bpp == 1) UNROLL1(1, op)\
205  else if(bpp == 2) UNROLL1(2, op)\
206  else if(bpp == 3) UNROLL1(3, op)\
207  else if(bpp == 4) UNROLL1(4, op)\
208  for (; i < size; i++) {\
209  dst[i] = op(dst[i-bpp], src[i], last[i]);\
210  }\
211 
212 /* NOTE: 'dst' can be equal to 'last' */
213 static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
214  uint8_t *src, uint8_t *last, int size, int bpp)
215 {
216  int i, p, r, g, b, a;
217 
218  switch(filter_type) {
219  case PNG_FILTER_VALUE_NONE:
220  memcpy(dst, src, size);
221  break;
222  case PNG_FILTER_VALUE_SUB:
223  for(i = 0; i < bpp; i++) {
224  dst[i] = src[i];
225  }
226  if(bpp == 4) {
227  p = *(int*)dst;
228  for(; i < size; i+=bpp) {
229  int s = *(int*)(src+i);
230  p = ((s&0x7f7f7f7f) + (p&0x7f7f7f7f)) ^ ((s^p)&0x80808080);
231  *(int*)(dst+i) = p;
232  }
233  } else {
234 #define OP_SUB(x,s,l) x+s
235  UNROLL_FILTER(OP_SUB);
236  }
237  break;
238  case PNG_FILTER_VALUE_UP:
239  dsp->add_bytes_l2(dst, src, last, size);
240  break;
241  case PNG_FILTER_VALUE_AVG:
242  for(i = 0; i < bpp; i++) {
243  p = (last[i] >> 1);
244  dst[i] = p + src[i];
245  }
246 #define OP_AVG(x,s,l) (((x + l) >> 1) + s) & 0xff
247  UNROLL_FILTER(OP_AVG);
248  break;
249  case PNG_FILTER_VALUE_PAETH:
250  for(i = 0; i < bpp; i++) {
251  p = last[i];
252  dst[i] = p + src[i];
253  }
254  if(bpp > 2 && size > 4) {
255  // would write off the end of the array if we let it process the last pixel with bpp=3
256  int w = bpp==4 ? size : size-3;
257  dsp->add_paeth_prediction(dst+i, src+i, last+i, w-i, bpp);
258  i = w;
259  }
260  ff_add_png_paeth_prediction(dst+i, src+i, last+i, size-i, bpp);
261  break;
262  }
263 }
264 
265 /* This used to be called "deloco" in FFmpeg
266  * and is actually an inverse reversible colorspace transformation */
267 #define YUV2RGB(NAME, TYPE) \
268 static void deloco_ ## NAME(TYPE *dst, int size, int alpha) \
269 { \
270  int i; \
271  for (i = 0; i < size; i += 3 + alpha) { \
272  int g = dst [i+1]; \
273  dst[i+0] += g; \
274  dst[i+2] += g; \
275  } \
276 }
277 
278 YUV2RGB(rgb8, uint8_t)
279 YUV2RGB(rgb16, uint16_t)
280 
281 /* process exactly one decompressed row */
282 static void png_handle_row(PNGDecContext *s)
283 {
284  uint8_t *ptr, *last_row;
285  int got_line;
286 
287  if (!s->interlace_type) {
288  ptr = s->image_buf + s->image_linesize * s->y;
289  if (s->y == 0)
290  last_row = s->last_row;
291  else
292  last_row = ptr - s->image_linesize;
293 
294  png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
295  last_row, s->row_size, s->bpp);
296  /* loco lags by 1 row so that it doesn't interfere with top prediction */
297  if (s->filter_type == PNG_FILTER_TYPE_LOCO && s->y > 0) {
298  if (s->bit_depth == 16) {
299  deloco_rgb16((uint16_t *)(ptr - s->image_linesize), s->row_size / 2,
300  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
301  } else {
302  deloco_rgb8(ptr - s->image_linesize, s->row_size,
303  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
304  }
305  }
306  s->y++;
307  if (s->y == s->height) {
308  s->state |= PNG_ALLIMAGE;
309  if (s->filter_type == PNG_FILTER_TYPE_LOCO) {
310  if (s->bit_depth == 16) {
311  deloco_rgb16((uint16_t *)ptr, s->row_size / 2,
312  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
313  } else {
314  deloco_rgb8(ptr, s->row_size,
315  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
316  }
317  }
318  }
319  } else {
320  got_line = 0;
321  for(;;) {
322  ptr = s->image_buf + s->image_linesize * s->y;
323  if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
324  /* if we already read one row, it is time to stop to
325  wait for the next one */
326  if (got_line)
327  break;
328  png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
329  s->last_row, s->pass_row_size, s->bpp);
330  FFSWAP(uint8_t*, s->last_row, s->tmp_row);
331  got_line = 1;
332  }
333  if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
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  memset(s->last_row, 0, s->row_size);
340  for(;;) {
341  if (s->pass == NB_PASSES - 1) {
342  s->state |= PNG_ALLIMAGE;
343  goto the_end;
344  } else {
345  s->pass++;
346  s->y = 0;
347  s->pass_row_size = ff_png_pass_row_size(s->pass,
348  s->bits_per_pixel,
349  s->width);
350  s->crow_size = s->pass_row_size + 1;
351  if (s->pass_row_size != 0)
352  break;
353  /* skip pass if empty row */
354  }
355  }
356  }
357  }
358  the_end: ;
359  }
360 }
361 
362 static int png_decode_idat(PNGDecContext *s, int length)
363 {
364  int ret;
365  s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
366  s->zstream.next_in = (unsigned char *)s->gb.buffer;
367  bytestream2_skip(&s->gb, length);
368 
369  /* decode one line if possible */
370  while (s->zstream.avail_in > 0) {
371  ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
372  if (ret != Z_OK && ret != Z_STREAM_END) {
373  av_log(s->avctx, AV_LOG_ERROR, "inflate returned %d\n", ret);
374  return -1;
375  }
376  if (s->zstream.avail_out == 0) {
377  if (!(s->state & PNG_ALLIMAGE)) {
378  png_handle_row(s);
379  }
380  s->zstream.avail_out = s->crow_size;
381  s->zstream.next_out = s->crow_buf;
382  }
383  }
384  return 0;
385 }
386 
387 static int decode_zbuf(AVBPrint *bp, const uint8_t *data,
388  const uint8_t *data_end)
389 {
390  z_stream zstream;
391  unsigned char *buf;
392  unsigned buf_size;
393  int ret;
394 
395  zstream.zalloc = ff_png_zalloc;
396  zstream.zfree = ff_png_zfree;
397  zstream.opaque = NULL;
398  if (inflateInit(&zstream) != Z_OK)
399  return AVERROR_EXTERNAL;
400  zstream.next_in = (unsigned char *)data;
401  zstream.avail_in = data_end - data;
402  av_bprint_init(bp, 0, -1);
403 
404  while (zstream.avail_in > 0) {
405  av_bprint_get_buffer(bp, 1, &buf, &buf_size);
406  if (!buf_size) {
407  ret = AVERROR(ENOMEM);
408  goto fail;
409  }
410  zstream.next_out = buf;
411  zstream.avail_out = buf_size;
412  ret = inflate(&zstream, Z_PARTIAL_FLUSH);
413  if (ret != Z_OK && ret != Z_STREAM_END) {
414  ret = AVERROR_EXTERNAL;
415  goto fail;
416  }
417  bp->len += zstream.next_out - buf;
418  if (ret == Z_STREAM_END)
419  break;
420  }
421  inflateEnd(&zstream);
422  bp->str[bp->len] = 0;
423  return 0;
424 
425 fail:
426  inflateEnd(&zstream);
427  av_bprint_finalize(bp, NULL);
428  return ret;
429 }
430 
431 static uint8_t *iso88591_to_utf8(const uint8_t *in, size_t size_in)
432 {
433  size_t extra = 0, i;
434  uint8_t *out, *q;
435 
436  for (i = 0; i < size_in; i++)
437  extra += in[i] >= 0x80;
438  if (size_in == SIZE_MAX || extra > SIZE_MAX - size_in - 1)
439  return NULL;
440  q = out = av_malloc(size_in + extra + 1);
441  if (!out)
442  return NULL;
443  for (i = 0; i < size_in; i++) {
444  if (in[i] >= 0x80) {
445  *(q++) = 0xC0 | (in[i] >> 6);
446  *(q++) = 0x80 | (in[i] & 0x3F);
447  } else {
448  *(q++) = in[i];
449  }
450  }
451  *(q++) = 0;
452  return out;
453 }
454 
455 static int decode_text_chunk(PNGDecContext *s, uint32_t length, int compressed,
456  AVDictionary **dict)
457 {
458  int ret, method;
459  const uint8_t *data = s->gb.buffer;
460  const uint8_t *data_end = data + length;
461  const uint8_t *keyword = data;
462  const uint8_t *keyword_end = memchr(keyword, 0, data_end - keyword);
463  uint8_t *kw_utf8 = NULL, *text, *txt_utf8 = NULL;
464  unsigned text_len;
465  AVBPrint bp;
466 
467  if (!keyword_end)
468  return AVERROR_INVALIDDATA;
469  data = keyword_end + 1;
470 
471  if (compressed) {
472  if (data == data_end)
473  return AVERROR_INVALIDDATA;
474  method = *(data++);
475  if (method)
476  return AVERROR_INVALIDDATA;
477  if ((ret = decode_zbuf(&bp, data, data_end)) < 0)
478  return ret;
479  text_len = bp.len;
480  av_bprint_finalize(&bp, (char **)&text);
481  if (!text)
482  return AVERROR(ENOMEM);
483  } else {
484  text = (uint8_t *)data;
485  text_len = data_end - text;
486  }
487 
488  kw_utf8 = iso88591_to_utf8(keyword, keyword_end - keyword);
489  txt_utf8 = iso88591_to_utf8(text, text_len);
490  if (text != data)
491  av_free(text);
492  if (!(kw_utf8 && txt_utf8)) {
493  av_free(kw_utf8);
494  av_free(txt_utf8);
495  return AVERROR(ENOMEM);
496  }
497 
498  av_dict_set(dict, kw_utf8, txt_utf8,
499  AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
500  return 0;
501 }
502 
503 static int decode_frame(AVCodecContext *avctx,
504  void *data, int *got_frame,
505  AVPacket *avpkt)
506 {
507  const uint8_t *buf = avpkt->data;
508  int buf_size = avpkt->size;
509  PNGDecContext * const s = avctx->priv_data;
510  AVFrame *picture = data;
511  AVFrame *p;
512  AVDictionary *metadata = NULL;
513  uint8_t *crow_buf_base = NULL;
514  uint32_t tag, length;
515  int64_t sig;
516  int ret;
517 
518  FFSWAP(AVFrame *, s->current_picture, s->last_picture);
519  avctx->coded_frame= s->current_picture;
520  p = s->current_picture;
521 
522  bytestream2_init(&s->gb, buf, buf_size);
523 
524  /* check signature */
525  sig = bytestream2_get_be64(&s->gb);
526  if (sig != PNGSIG &&
527  sig != MNGSIG) {
528  av_log(avctx, AV_LOG_ERROR, "Missing png signature\n");
529  return -1;
530  }
531 
532  s->y=
533  s->state=0;
534 // memset(s, 0, sizeof(PNGDecContext));
535  /* init the zlib */
536  s->zstream.zalloc = ff_png_zalloc;
537  s->zstream.zfree = ff_png_zfree;
538  s->zstream.opaque = NULL;
539  ret = inflateInit(&s->zstream);
540  if (ret != Z_OK) {
541  av_log(avctx, AV_LOG_ERROR, "inflateInit returned %d\n", ret);
542  return -1;
543  }
544  for(;;) {
545  if (bytestream2_get_bytes_left(&s->gb) <= 0) {
546  av_log(avctx, AV_LOG_ERROR, "No bytes left\n");
547  goto fail;
548  }
549 
550  length = bytestream2_get_be32(&s->gb);
551  if (length > 0x7fffffff || length > bytestream2_get_bytes_left(&s->gb)) {
552  av_log(avctx, AV_LOG_ERROR, "chunk too big\n");
553  goto fail;
554  }
555  tag = bytestream2_get_le32(&s->gb);
556  if (avctx->debug & FF_DEBUG_STARTCODE)
557  av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
558  (tag & 0xff),
559  ((tag >> 8) & 0xff),
560  ((tag >> 16) & 0xff),
561  ((tag >> 24) & 0xff), length);
562  switch(tag) {
563  case MKTAG('I', 'H', 'D', 'R'):
564  if (length != 13)
565  goto fail;
566  s->width = bytestream2_get_be32(&s->gb);
567  s->height = bytestream2_get_be32(&s->gb);
568  if(av_image_check_size(s->width, s->height, 0, avctx)){
569  s->width= s->height= 0;
570  av_log(avctx, AV_LOG_ERROR, "Invalid image size\n");
571  goto fail;
572  }
573  s->bit_depth = bytestream2_get_byte(&s->gb);
574  s->color_type = bytestream2_get_byte(&s->gb);
575  s->compression_type = bytestream2_get_byte(&s->gb);
576  s->filter_type = bytestream2_get_byte(&s->gb);
577  s->interlace_type = bytestream2_get_byte(&s->gb);
578  bytestream2_skip(&s->gb, 4); /* crc */
579  s->state |= PNG_IHDR;
580  if (avctx->debug & FF_DEBUG_PICT_INFO)
581  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",
582  s->width, s->height, s->bit_depth, s->color_type,
583  s->compression_type, s->filter_type, s->interlace_type);
584  break;
585  case MKTAG('p', 'H', 'Y', 's'):
586  if (s->state & PNG_IDAT) {
587  av_log(avctx, AV_LOG_ERROR, "pHYs after IDAT\n");
588  goto fail;
589  }
590  avctx->sample_aspect_ratio.num = bytestream2_get_be32(&s->gb);
591  avctx->sample_aspect_ratio.den = bytestream2_get_be32(&s->gb);
592  if (avctx->sample_aspect_ratio.num < 0 || avctx->sample_aspect_ratio.den < 0)
593  avctx->sample_aspect_ratio = (AVRational){ 0, 1 };
594  bytestream2_skip(&s->gb, 1); /* unit specifier */
595  bytestream2_skip(&s->gb, 4); /* crc */
596  break;
597  case MKTAG('I', 'D', 'A', 'T'):
598  if (!(s->state & PNG_IHDR)) {
599  av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
600  goto fail;
601  }
602  if (!(s->state & PNG_IDAT)) {
603  /* init image info */
604  avctx->width = s->width;
605  avctx->height = s->height;
606 
607  s->channels = ff_png_get_nb_channels(s->color_type);
608  s->bits_per_pixel = s->bit_depth * s->channels;
609  s->bpp = (s->bits_per_pixel + 7) >> 3;
610  s->row_size = (avctx->width * s->bits_per_pixel + 7) >> 3;
611 
612  if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
613  s->color_type == PNG_COLOR_TYPE_RGB) {
614  avctx->pix_fmt = AV_PIX_FMT_RGB24;
615  } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
616  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
617  avctx->pix_fmt = AV_PIX_FMT_RGBA;
618  } else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
619  s->color_type == PNG_COLOR_TYPE_GRAY) {
620  avctx->pix_fmt = AV_PIX_FMT_GRAY8;
621  } else if (s->bit_depth == 16 &&
622  s->color_type == PNG_COLOR_TYPE_GRAY) {
623  avctx->pix_fmt = AV_PIX_FMT_GRAY16BE;
624  } else if (s->bit_depth == 16 &&
625  s->color_type == PNG_COLOR_TYPE_RGB) {
626  avctx->pix_fmt = AV_PIX_FMT_RGB48BE;
627  } else if (s->bit_depth == 16 &&
628  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
629  avctx->pix_fmt = AV_PIX_FMT_RGBA64BE;
630  } else if ((s->bits_per_pixel == 1 || s->bits_per_pixel == 2 || s->bits_per_pixel == 4 || s->bits_per_pixel == 8) &&
631  s->color_type == PNG_COLOR_TYPE_PALETTE) {
632  avctx->pix_fmt = AV_PIX_FMT_PAL8;
633  } else if (s->bit_depth == 1) {
634  avctx->pix_fmt = AV_PIX_FMT_MONOBLACK;
635  } else if (s->bit_depth == 8 &&
636  s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
637  avctx->pix_fmt = AV_PIX_FMT_Y400A;
638  } else {
639  av_log(avctx, AV_LOG_ERROR, "unsupported bit depth %d "
640  "and color type %d\n",
641  s->bit_depth, s->color_type);
642  goto fail;
643  }
644  if(p->data[0])
645  avctx->release_buffer(avctx, p);
646 
647  p->reference= 3;
648  if(ff_get_buffer(avctx, p) < 0){
649  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
650  goto fail;
651  }
652  p->pict_type= AV_PICTURE_TYPE_I;
653  p->key_frame= 1;
654  p->interlaced_frame = !!s->interlace_type;
655 
656  /* compute the compressed row size */
657  if (!s->interlace_type) {
658  s->crow_size = s->row_size + 1;
659  } else {
660  s->pass = 0;
661  s->pass_row_size = ff_png_pass_row_size(s->pass,
662  s->bits_per_pixel,
663  s->width);
664  s->crow_size = s->pass_row_size + 1;
665  }
666  av_dlog(avctx, "row_size=%d crow_size =%d\n",
667  s->row_size, s->crow_size);
668  s->image_buf = p->data[0];
669  s->image_linesize = p->linesize[0];
670  /* copy the palette if needed */
671  if (avctx->pix_fmt == AV_PIX_FMT_PAL8)
672  memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
673  /* empty row is used if differencing to the first row */
674  s->last_row = av_mallocz(s->row_size);
675  if (!s->last_row)
676  goto fail;
677  if (s->interlace_type ||
678  s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
679  s->tmp_row = av_malloc(s->row_size);
680  if (!s->tmp_row)
681  goto fail;
682  }
683  /* compressed row */
684  crow_buf_base = av_malloc(s->row_size + 16);
685  if (!crow_buf_base)
686  goto fail;
687 
688  /* we want crow_buf+1 to be 16-byte aligned */
689  s->crow_buf = crow_buf_base + 15;
690  s->zstream.avail_out = s->crow_size;
691  s->zstream.next_out = s->crow_buf;
692  }
693  s->state |= PNG_IDAT;
694  if (png_decode_idat(s, length) < 0)
695  goto fail;
696  bytestream2_skip(&s->gb, 4); /* crc */
697  break;
698  case MKTAG('P', 'L', 'T', 'E'):
699  {
700  int n, i, r, g, b;
701 
702  if ((length % 3) != 0 || length > 256 * 3)
703  goto skip_tag;
704  /* read the palette */
705  n = length / 3;
706  for(i=0;i<n;i++) {
707  r = bytestream2_get_byte(&s->gb);
708  g = bytestream2_get_byte(&s->gb);
709  b = bytestream2_get_byte(&s->gb);
710  s->palette[i] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
711  }
712  for(;i<256;i++) {
713  s->palette[i] = (0xFFU << 24);
714  }
715  s->state |= PNG_PLTE;
716  bytestream2_skip(&s->gb, 4); /* crc */
717  }
718  break;
719  case MKTAG('t', 'R', 'N', 'S'):
720  {
721  int v, i;
722 
723  /* read the transparency. XXX: Only palette mode supported */
724  if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
725  length > 256 ||
726  !(s->state & PNG_PLTE))
727  goto skip_tag;
728  for(i=0;i<length;i++) {
729  v = bytestream2_get_byte(&s->gb);
730  s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
731  }
732  bytestream2_skip(&s->gb, 4); /* crc */
733  }
734  break;
735  case MKTAG('t', 'E', 'X', 't'):
736  if (decode_text_chunk(s, length, 0, &metadata) < 0)
737  av_log(avctx, AV_LOG_WARNING, "Broken tEXt chunk\n");
738  bytestream2_skip(&s->gb, length + 4);
739  break;
740  case MKTAG('z', 'T', 'X', 't'):
741  if (decode_text_chunk(s, length, 1, &metadata) < 0)
742  av_log(avctx, AV_LOG_WARNING, "Broken zTXt chunk\n");
743  bytestream2_skip(&s->gb, length + 4);
744  break;
745  case MKTAG('I', 'E', 'N', 'D'):
746  if (!(s->state & PNG_ALLIMAGE))
747  av_log(avctx, AV_LOG_ERROR, "IEND without all image\n");
748  if (!(s->state & (PNG_ALLIMAGE|PNG_IDAT))) {
749  goto fail;
750  }
751  bytestream2_skip(&s->gb, 4); /* crc */
752  goto exit_loop;
753  default:
754  /* skip tag */
755  skip_tag:
756  bytestream2_skip(&s->gb, length + 4);
757  break;
758  }
759  }
760  exit_loop:
761 
762  if(s->bits_per_pixel == 1 && s->color_type == PNG_COLOR_TYPE_PALETTE){
763  int i, j;
764  uint8_t *pd = s->current_picture->data[0];
765  for(j=0; j < s->height; j++) {
766  for(i=s->width/8-1; i>=0; i--) {
767  pd[8*i+7]= pd[i] &1;
768  pd[8*i+6]= (pd[i]>>1)&1;
769  pd[8*i+5]= (pd[i]>>2)&1;
770  pd[8*i+4]= (pd[i]>>3)&1;
771  pd[8*i+3]= (pd[i]>>4)&1;
772  pd[8*i+2]= (pd[i]>>5)&1;
773  pd[8*i+1]= (pd[i]>>6)&1;
774  pd[8*i+0]= pd[i]>>7;
775  }
776  pd += s->image_linesize;
777  }
778  }
779  if(s->bits_per_pixel == 2){
780  int i, j;
781  uint8_t *pd = s->current_picture->data[0];
782  for(j=0; j < s->height; j++) {
783  i = s->width/4;
784  if (s->color_type == PNG_COLOR_TYPE_PALETTE){
785  if ((s->width&3) >= 3) pd[4*i+2]= (pd[i]>>2)&3;
786  if ((s->width&3) >= 2) pd[4*i+1]= (pd[i]>>4)&3;
787  if ((s->width&3) >= 1) pd[4*i+0]= pd[i]>>6;
788  for(i--; i>=0; i--) {
789  pd[4*i+3]= pd[i] &3;
790  pd[4*i+2]= (pd[i]>>2)&3;
791  pd[4*i+1]= (pd[i]>>4)&3;
792  pd[4*i+0]= pd[i]>>6;
793  }
794  } else {
795  if ((s->width&3) >= 3) pd[4*i+2]= ((pd[i]>>2)&3)*0x55;
796  if ((s->width&3) >= 2) pd[4*i+1]= ((pd[i]>>4)&3)*0x55;
797  if ((s->width&3) >= 1) pd[4*i+0]= ( pd[i]>>6 )*0x55;
798  for(i--; i>=0; i--) {
799  pd[4*i+3]= ( pd[i] &3)*0x55;
800  pd[4*i+2]= ((pd[i]>>2)&3)*0x55;
801  pd[4*i+1]= ((pd[i]>>4)&3)*0x55;
802  pd[4*i+0]= ( pd[i]>>6 )*0x55;
803  }
804  }
805  pd += s->image_linesize;
806  }
807  }
808  if(s->bits_per_pixel == 4){
809  int i, j;
810  uint8_t *pd = s->current_picture->data[0];
811  for(j=0; j < s->height; j++) {
812  i=s->width/2;
813  if (s->color_type == PNG_COLOR_TYPE_PALETTE){
814  if (s->width&1) pd[2*i+0]= pd[i]>>4;
815  for(i--; i>=0; i--) {
816  pd[2*i+1]= pd[i]&15;
817  pd[2*i+0]= pd[i]>>4;
818  }
819  } else {
820  if (s->width&1) pd[2*i+0]= (pd[i]>>4)*0x11;
821  for(i--; i>=0; i--) {
822  pd[2*i+1]= (pd[i]&15)*0x11;
823  pd[2*i+0]= (pd[i]>>4)*0x11;
824  }
825  }
826  pd += s->image_linesize;
827  }
828  }
829 
830  /* handle p-frames only if a predecessor frame is available */
831  if(s->last_picture->data[0] != NULL) {
832  if( !(avpkt->flags & AV_PKT_FLAG_KEY)
833  && s->last_picture->width == s->current_picture->width
834  && s->last_picture->height== s->current_picture->height
835  && s->last_picture->format== s->current_picture->format
836  ) {
837  int i, j;
838  uint8_t *pd = s->current_picture->data[0];
839  uint8_t *pd_last = s->last_picture->data[0];
840 
841  for(j=0; j < s->height; j++) {
842  for(i=0; i < s->width * s->bpp; i++) {
843  pd[i] += pd_last[i];
844  }
845  pd += s->image_linesize;
846  pd_last += s->image_linesize;
847  }
848  }
849  }
850 
851  s->current_picture->metadata = metadata;
852  metadata = NULL;
853  *picture= *s->current_picture;
854  *got_frame = 1;
855 
856  ret = bytestream2_tell(&s->gb);
857  the_end:
858  inflateEnd(&s->zstream);
859  av_free(crow_buf_base);
860  s->crow_buf = NULL;
861  av_freep(&s->last_row);
862  av_freep(&s->tmp_row);
863  return ret;
864  fail:
865  av_dict_free(&metadata);
866  ret = -1;
867  goto the_end;
868 }
869 
870 static av_cold int png_dec_init(AVCodecContext *avctx)
871 {
872  PNGDecContext *s = avctx->priv_data;
873 
874  s->current_picture = &s->picture1;
875  s->last_picture = &s->picture2;
876  avcodec_get_frame_defaults(&s->picture1);
877  avcodec_get_frame_defaults(&s->picture2);
878 
879  ff_pngdsp_init(&s->dsp);
880 
881  s->avctx = avctx;
882 
883  return 0;
884 }
885 
886 static av_cold int png_dec_end(AVCodecContext *avctx)
887 {
888  PNGDecContext *s = avctx->priv_data;
889 
890  if (s->picture1.data[0])
891  avctx->release_buffer(avctx, &s->picture1);
892  if (s->picture2.data[0])
893  avctx->release_buffer(avctx, &s->picture2);
894 
895  return 0;
896 }
897 
898 AVCodec ff_png_decoder = {
899  .name = "png",
900  .type = AVMEDIA_TYPE_VIDEO,
901  .id = AV_CODEC_ID_PNG,
902  .priv_data_size = sizeof(PNGDecContext),
903  .init = png_dec_init,
904  .close = png_dec_end,
905  .decode = decode_frame,
906  .capabilities = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
907  .long_name = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
908 };
Generated on Sat May 25 2013 03:58:39 for FFmpeg by   doxygen 1.8.2