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pngenc.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 #include "avcodec.h"
22 #include "internal.h"
23 #include "bytestream.h"
24 #include "dsputil.h"
25 #include "png.h"
26 
27 #include "libavutil/avassert.h"
28 
29 /* TODO:
30  * - add 2, 4 and 16 bit depth support
31  */
32 
33 #include <zlib.h>
34 
35 //#define DEBUG
36 
37 #define IOBUF_SIZE 4096
38 
39 typedef struct PNGEncContext {
41 
46 
48 
49  z_stream zstream;
52 
53 static void png_get_interlaced_row(uint8_t *dst, int row_size,
54  int bits_per_pixel, int pass,
55  const uint8_t *src, int width)
56 {
57  int x, mask, dst_x, j, b, bpp;
58  uint8_t *d;
59  const uint8_t *s;
60 
61  mask = (int[]){0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff}[pass];
62  switch(bits_per_pixel) {
63  case 1:
64  memset(dst, 0, row_size);
65  dst_x = 0;
66  for(x = 0; x < width; x++) {
67  j = (x & 7);
68  if ((mask << j) & 0x80) {
69  b = (src[x >> 3] >> (7 - j)) & 1;
70  dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
71  dst_x++;
72  }
73  }
74  break;
75  default:
76  bpp = bits_per_pixel >> 3;
77  d = dst;
78  s = src;
79  for(x = 0; x < width; x++) {
80  j = x & 7;
81  if ((mask << j) & 0x80) {
82  memcpy(d, s, bpp);
83  d += bpp;
84  }
85  s += bpp;
86  }
87  break;
88  }
89 }
90 
91 static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
92 {
93  int i;
94  for(i = 0; i < w; i++) {
95  int a, b, c, p, pa, pb, pc;
96 
97  a = src[i - bpp];
98  b = top[i];
99  c = top[i - bpp];
100 
101  p = b - c;
102  pc = a - c;
103 
104  pa = abs(p);
105  pb = abs(pc);
106  pc = abs(p + pc);
107 
108  if (pa <= pb && pa <= pc)
109  p = a;
110  else if (pb <= pc)
111  p = b;
112  else
113  p = c;
114  dst[i] = src[i] - p;
115  }
116 }
117 
118 static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
119  uint8_t *src, uint8_t *top, int size, int bpp)
120 {
121  int i;
122 
123  switch(filter_type) {
125  memcpy(dst, src, size);
126  break;
128  dsp->diff_bytes(dst, src, src-bpp, size);
129  memcpy(dst, src, bpp);
130  break;
131  case PNG_FILTER_VALUE_UP:
132  dsp->diff_bytes(dst, src, top, size);
133  break;
135  for(i = 0; i < bpp; i++)
136  dst[i] = src[i] - (top[i] >> 1);
137  for(; i < size; i++)
138  dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
139  break;
141  for(i = 0; i < bpp; i++)
142  dst[i] = src[i] - top[i];
143  sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
144  break;
145  }
146 }
147 
149  uint8_t *src, uint8_t *top, int size, int bpp)
150 {
151  int pred = s->filter_type;
152  av_assert0(bpp || !pred);
153  if(!top && pred)
154  pred = PNG_FILTER_VALUE_SUB;
155  if(pred == PNG_FILTER_VALUE_MIXED) {
156  int i;
157  int cost, bcost = INT_MAX;
158  uint8_t *buf1 = dst, *buf2 = dst + size + 16;
159  for(pred=0; pred<5; pred++) {
160  png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
161  buf1[0] = pred;
162  cost = 0;
163  for(i=0; i<=size; i++)
164  cost += abs((int8_t)buf1[i]);
165  if(cost < bcost) {
166  bcost = cost;
167  FFSWAP(uint8_t*, buf1, buf2);
168  }
169  }
170  return buf2;
171  } else {
172  png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
173  dst[0] = pred;
174  return dst;
175  }
176 }
177 
178 static void png_write_chunk(uint8_t **f, uint32_t tag,
179  const uint8_t *buf, int length)
180 {
181  uint32_t crc;
182  uint8_t tagbuf[4];
183 
184  bytestream_put_be32(f, length);
185  crc = crc32(0, Z_NULL, 0);
186  AV_WL32(tagbuf, tag);
187  crc = crc32(crc, tagbuf, 4);
188  bytestream_put_be32(f, av_bswap32(tag));
189  if (length > 0) {
190  crc = crc32(crc, buf, length);
191  memcpy(*f, buf, length);
192  *f += length;
193  }
194  bytestream_put_be32(f, crc);
195 }
196 
197 /* XXX: do filtering */
198 static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
199 {
200  int ret;
201 
202  s->zstream.avail_in = size;
203  s->zstream.next_in = (uint8_t *)data;
204  while (s->zstream.avail_in > 0) {
205  ret = deflate(&s->zstream, Z_NO_FLUSH);
206  if (ret != Z_OK)
207  return -1;
208  if (s->zstream.avail_out == 0) {
209  if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
210  png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
211  s->zstream.avail_out = IOBUF_SIZE;
212  s->zstream.next_out = s->buf;
213  }
214  }
215  return 0;
216 }
217 
219  const AVFrame *pict, int *got_packet)
220 {
221  PNGEncContext *s = avctx->priv_data;
222  AVFrame * const p= &s->picture;
223  int bit_depth, color_type, y, len, row_size, ret, is_progressive;
224  int bits_per_pixel, pass_row_size, enc_row_size;
225  int64_t max_packet_size;
226  int compression_level;
227  uint8_t *ptr, *top;
228  uint8_t *crow_base = NULL, *crow_buf, *crow;
229  uint8_t *progressive_buf = NULL;
230  uint8_t *top_buf = NULL;
231 
232  *p = *pict;
234  p->key_frame= 1;
235 
236  is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
237  switch(avctx->pix_fmt) {
238  case AV_PIX_FMT_RGBA64BE:
239  bit_depth = 16;
240  color_type = PNG_COLOR_TYPE_RGB_ALPHA;
241  break;
242  case AV_PIX_FMT_RGB48BE:
243  bit_depth = 16;
244  color_type = PNG_COLOR_TYPE_RGB;
245  break;
246  case AV_PIX_FMT_RGBA:
247  bit_depth = 8;
248  color_type = PNG_COLOR_TYPE_RGB_ALPHA;
249  break;
250  case AV_PIX_FMT_RGB24:
251  bit_depth = 8;
252  color_type = PNG_COLOR_TYPE_RGB;
253  break;
254  case AV_PIX_FMT_GRAY16BE:
255  bit_depth = 16;
256  color_type = PNG_COLOR_TYPE_GRAY;
257  break;
258  case AV_PIX_FMT_GRAY8:
259  bit_depth = 8;
260  color_type = PNG_COLOR_TYPE_GRAY;
261  break;
262  case AV_PIX_FMT_GRAY8A:
263  bit_depth = 8;
264  color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
265  break;
267  bit_depth = 1;
268  color_type = PNG_COLOR_TYPE_GRAY;
269  break;
270  case AV_PIX_FMT_PAL8:
271  bit_depth = 8;
272  color_type = PNG_COLOR_TYPE_PALETTE;
273  break;
274  default:
275  return -1;
276  }
277  bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;
278  row_size = (avctx->width * bits_per_pixel + 7) >> 3;
279 
280  s->zstream.zalloc = ff_png_zalloc;
281  s->zstream.zfree = ff_png_zfree;
282  s->zstream.opaque = NULL;
283  compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT ?
284  Z_DEFAULT_COMPRESSION :
285  av_clip(avctx->compression_level, 0, 9);
286  ret = deflateInit2(&s->zstream, compression_level,
287  Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
288  if (ret != Z_OK)
289  return -1;
290 
291  enc_row_size = deflateBound(&s->zstream, row_size);
292  max_packet_size = avctx->height * (int64_t)(enc_row_size +
293  ((enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) * 12)
295  if (max_packet_size > INT_MAX)
296  return AVERROR(ENOMEM);
297  if ((ret = ff_alloc_packet2(avctx, pkt, max_packet_size)) < 0)
298  return ret;
299 
300  s->bytestream_start =
301  s->bytestream = pkt->data;
302  s->bytestream_end = pkt->data + pkt->size;
303 
304  crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
305  if (!crow_base)
306  goto fail;
307  crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
308  if (is_progressive) {
309  progressive_buf = av_malloc(row_size + 1);
310  if (!progressive_buf)
311  goto fail;
312  }
313  if (is_progressive) {
314  top_buf = av_malloc(row_size + 1);
315  if (!top_buf)
316  goto fail;
317  }
318 
319  /* write png header */
321  s->bytestream += 8;
322 
323  AV_WB32(s->buf, avctx->width);
324  AV_WB32(s->buf + 4, avctx->height);
325  s->buf[8] = bit_depth;
326  s->buf[9] = color_type;
327  s->buf[10] = 0; /* compression type */
328  s->buf[11] = 0; /* filter type */
329  s->buf[12] = is_progressive; /* interlace type */
330 
331  png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
332 
333  AV_WB32(s->buf, avctx->sample_aspect_ratio.num);
334  AV_WB32(s->buf + 4, avctx->sample_aspect_ratio.den);
335  s->buf[8] = 0; /* unit specifier is unknown */
336  png_write_chunk(&s->bytestream, MKTAG('p', 'H', 'Y', 's'), s->buf, 9);
337 
338  /* put the palette if needed */
339  if (color_type == PNG_COLOR_TYPE_PALETTE) {
340  int has_alpha, alpha, i;
341  unsigned int v;
342  uint32_t *palette;
343  uint8_t *alpha_ptr;
344 
345  palette = (uint32_t *)p->data[1];
346  ptr = s->buf;
347  alpha_ptr = s->buf + 256 * 3;
348  has_alpha = 0;
349  for(i = 0; i < 256; i++) {
350  v = palette[i];
351  alpha = v >> 24;
352  if (alpha != 0xff)
353  has_alpha = 1;
354  *alpha_ptr++ = alpha;
355  bytestream_put_be24(&ptr, v);
356  }
357  png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
358  if (has_alpha) {
359  png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
360  }
361  }
362 
363  /* now put each row */
364  s->zstream.avail_out = IOBUF_SIZE;
365  s->zstream.next_out = s->buf;
366  if (is_progressive) {
367  int pass;
368 
369  for(pass = 0; pass < NB_PASSES; pass++) {
370  /* NOTE: a pass is completely omitted if no pixels would be
371  output */
372  pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
373  if (pass_row_size > 0) {
374  top = NULL;
375  for(y = 0; y < avctx->height; y++) {
376  if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
377  ptr = p->data[0] + y * p->linesize[0];
378  FFSWAP(uint8_t*, progressive_buf, top_buf);
379  png_get_interlaced_row(progressive_buf, pass_row_size,
380  bits_per_pixel, pass,
381  ptr, avctx->width);
382  crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
383  png_write_row(s, crow, pass_row_size + 1);
384  top = progressive_buf;
385  }
386  }
387  }
388  }
389  } else {
390  top = NULL;
391  for(y = 0; y < avctx->height; y++) {
392  ptr = p->data[0] + y * p->linesize[0];
393  crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
394  png_write_row(s, crow, row_size + 1);
395  top = ptr;
396  }
397  }
398  /* compress last bytes */
399  for(;;) {
400  ret = deflate(&s->zstream, Z_FINISH);
401  if (ret == Z_OK || ret == Z_STREAM_END) {
402  len = IOBUF_SIZE - s->zstream.avail_out;
403  if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
404  png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
405  }
406  s->zstream.avail_out = IOBUF_SIZE;
407  s->zstream.next_out = s->buf;
408  if (ret == Z_STREAM_END)
409  break;
410  } else {
411  goto fail;
412  }
413  }
414  png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
415 
416  pkt->size = s->bytestream - s->bytestream_start;
417  pkt->flags |= AV_PKT_FLAG_KEY;
418  *got_packet = 1;
419  ret = 0;
420 
421  the_end:
422  av_free(crow_base);
423  av_free(progressive_buf);
424  av_free(top_buf);
425  deflateEnd(&s->zstream);
426  return ret;
427  fail:
428  ret = -1;
429  goto the_end;
430 }
431 
433  PNGEncContext *s = avctx->priv_data;
434 
435  switch(avctx->pix_fmt) {
436  case AV_PIX_FMT_RGBA:
437  avctx->bits_per_coded_sample = 32;
438  break;
439  case AV_PIX_FMT_RGB24:
440  avctx->bits_per_coded_sample = 24;
441  break;
442  case AV_PIX_FMT_GRAY8:
443  avctx->bits_per_coded_sample = 0x28;
444  break;
446  avctx->bits_per_coded_sample = 1;
447  break;
448  case AV_PIX_FMT_PAL8:
449  avctx->bits_per_coded_sample = 8;
450  }
451 
453  avctx->coded_frame= &s->picture;
454  ff_dsputil_init(&s->dsp, avctx);
455 
457  if(avctx->pix_fmt == AV_PIX_FMT_MONOBLACK)
459 
460  return 0;
461 }
462 
464  .name = "png",
465  .type = AVMEDIA_TYPE_VIDEO,
466  .id = AV_CODEC_ID_PNG,
467  .priv_data_size = sizeof(PNGEncContext),
468  .init = png_enc_init,
469  .encode2 = encode_frame,
471  .pix_fmts = (const enum AVPixelFormat[]){
478  },
479  .long_name = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
480 };