lagarith.c
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1 /*
2  * Lagarith lossless decoder
3  * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "avcodec.h"
29 #include "get_bits.h"
30 #include "mathops.h"
31 #include "dsputil.h"
32 #include "lagarithrac.h"
33 
35  FRAME_RAW = 1,
46 };
47 
48 typedef struct LagarithContext {
52  int zeros;
53  int zeros_rem;
54  uint8_t *rgb_planes;
58 
67 static uint64_t softfloat_reciprocal(uint32_t denom)
68 {
69  int shift = av_log2(denom - 1) + 1;
70  uint64_t ret = (1ULL << 52) / denom;
71  uint64_t err = (1ULL << 52) - ret * denom;
72  ret <<= shift;
73  err <<= shift;
74  err += denom / 2;
75  return ret + err / denom;
76 }
77 
86 static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
87 {
88  uint64_t l = x * (mantissa & 0xffffffff);
89  uint64_t h = x * (mantissa >> 32);
90  h += l >> 32;
91  l &= 0xffffffff;
92  l += 1 << av_log2(h >> 21);
93  h += l >> 32;
94  return h >> 20;
95 }
96 
97 static uint8_t lag_calc_zero_run(int8_t x)
98 {
99  return (x << 1) ^ (x >> 7);
100 }
101 
102 static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
103 {
104  static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
105  int i;
106  int bit = 0;
107  int bits = 0;
108  int prevbit = 0;
109  unsigned val;
110 
111  for (i = 0; i < 7; i++) {
112  if (prevbit && bit)
113  break;
114  prevbit = bit;
115  bit = get_bits1(gb);
116  if (bit && !prevbit)
117  bits += series[i];
118  }
119  bits--;
120  if (bits < 0 || bits > 31) {
121  *value = 0;
122  return -1;
123  } else if (bits == 0) {
124  *value = 0;
125  return 0;
126  }
127 
128  val = get_bits_long(gb, bits);
129  val |= 1 << bits;
130 
131  *value = val - 1;
132 
133  return 0;
134 }
135 
137 {
138  int i, j, scale_factor;
139  unsigned prob, cumulative_target;
140  unsigned cumul_prob = 0;
141  unsigned scaled_cumul_prob = 0;
142 
143  rac->prob[0] = 0;
144  rac->prob[257] = UINT_MAX;
145  /* Read probabilities from bitstream */
146  for (i = 1; i < 257; i++) {
147  if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
148  av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
149  return -1;
150  }
151  if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
152  av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
153  return -1;
154  }
155  cumul_prob += rac->prob[i];
156  if (!rac->prob[i]) {
157  if (lag_decode_prob(gb, &prob)) {
158  av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
159  return -1;
160  }
161  if (prob > 257 - i)
162  prob = 257 - i;
163  for (j = 0; j < prob; j++)
164  rac->prob[++i] = 0;
165  }
166  }
167 
168  if (!cumul_prob) {
169  av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
170  return -1;
171  }
172 
173  /* Scale probabilities so cumulative probability is an even power of 2. */
174  scale_factor = av_log2(cumul_prob);
175 
176  if (cumul_prob & (cumul_prob - 1)) {
177  uint64_t mul = softfloat_reciprocal(cumul_prob);
178  for (i = 1; i < 257; i++) {
179  rac->prob[i] = softfloat_mul(rac->prob[i], mul);
180  scaled_cumul_prob += rac->prob[i];
181  }
182 
183  scale_factor++;
184  cumulative_target = 1 << scale_factor;
185 
186  if (scaled_cumul_prob > cumulative_target) {
187  av_log(rac->avctx, AV_LOG_ERROR,
188  "Scaled probabilities are larger than target!\n");
189  return -1;
190  }
191 
192  scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
193 
194  for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
195  if (rac->prob[i]) {
196  rac->prob[i]++;
197  scaled_cumul_prob--;
198  }
199  /* Comment from reference source:
200  * if (b & 0x80 == 0) { // order of operations is 'wrong'; it has been left this way
201  * // since the compression change is negligable and fixing it
202  * // breaks backwards compatibilty
203  * b =- (signed int)b;
204  * b &= 0xFF;
205  * } else {
206  * b++;
207  * b &= 0x7f;
208  * }
209  */
210  }
211  }
212 
213  rac->scale = scale_factor;
214 
215  /* Fill probability array with cumulative probability for each symbol. */
216  for (i = 1; i < 257; i++)
217  rac->prob[i] += rac->prob[i - 1];
218 
219  return 0;
220 }
221 
222 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
223  uint8_t *diff, int w, int *left,
224  int *left_top)
225 {
226  /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
227  * However the &0xFF on the gradient predictor yealds incorrect output
228  * for lagarith.
229  */
230  int i;
231  uint8_t l, lt;
232 
233  l = *left;
234  lt = *left_top;
235 
236  for (i = 0; i < w; i++) {
237  l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
238  lt = src1[i];
239  dst[i] = l;
240  }
241 
242  *left = l;
243  *left_top = lt;
244 }
245 
246 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
247  int width, int stride, int line)
248 {
249  int L, TL;
250 
251  if (!line) {
252  /* Left prediction only for first line */
253  L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
254  width - 1, buf[0]);
255  } else {
256  /* Left pixel is actually prev_row[width] */
257  L = buf[width - stride - 1];
258 
259  if (line == 1) {
260  /* Second line, left predict first pixel, the rest of the line is median predicted
261  * NOTE: In the case of RGB this pixel is top predicted */
262  TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
263  } else {
264  /* Top left is 2 rows back, last pixel */
265  TL = buf[width - (2 * stride) - 1];
266  }
267 
268  add_lag_median_prediction(buf, buf - stride, buf,
269  width, &L, &TL);
270  }
271 }
272 
274  uint8_t *dst, int width, int stride,
275  int esc_count)
276 {
277  int i = 0;
278  int ret = 0;
279 
280  if (!esc_count)
281  esc_count = -1;
282 
283  /* Output any zeros remaining from the previous run */
284 handle_zeros:
285  if (l->zeros_rem) {
286  int count = FFMIN(l->zeros_rem, width - i);
287  memset(dst + i, 0, count);
288  i += count;
289  l->zeros_rem -= count;
290  }
291 
292  while (i < width) {
293  dst[i] = lag_get_rac(rac);
294  ret++;
295 
296  if (dst[i])
297  l->zeros = 0;
298  else
299  l->zeros++;
300 
301  i++;
302  if (l->zeros == esc_count) {
303  int index = lag_get_rac(rac);
304  ret++;
305 
306  l->zeros = 0;
307 
308  l->zeros_rem = lag_calc_zero_run(index);
309  goto handle_zeros;
310  }
311  }
312  return ret;
313 }
314 
315 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
316  const uint8_t *src, const uint8_t *src_end,
317  int width, int esc_count)
318 {
319  int i = 0;
320  int count;
321  uint8_t zero_run = 0;
322  const uint8_t *src_start = src;
323  uint8_t mask1 = -(esc_count < 2);
324  uint8_t mask2 = -(esc_count < 3);
325  uint8_t *end = dst + (width - 2);
326 
327 output_zeros:
328  if (l->zeros_rem) {
329  count = FFMIN(l->zeros_rem, width - i);
330  if (end - dst < count) {
331  av_log(l->avctx, AV_LOG_ERROR, "Too many zeros remaining.\n");
332  return AVERROR_INVALIDDATA;
333  }
334 
335  memset(dst, 0, count);
336  l->zeros_rem -= count;
337  dst += count;
338  }
339 
340  while (dst < end) {
341  i = 0;
342  while (!zero_run && dst + i < end) {
343  i++;
344  if (src + i >= src_end)
345  return AVERROR_INVALIDDATA;
346  zero_run =
347  !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
348  }
349  if (zero_run) {
350  zero_run = 0;
351  i += esc_count;
352  memcpy(dst, src, i);
353  dst += i;
354  l->zeros_rem = lag_calc_zero_run(src[i]);
355 
356  src += i + 1;
357  goto output_zeros;
358  } else {
359  memcpy(dst, src, i);
360  src += i;
361  dst += i;
362  }
363  }
364  return src_start - src;
365 }
366 
367 
368 
369 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
370  int width, int height, int stride,
371  const uint8_t *src, int src_size)
372 {
373  int i = 0;
374  int read = 0;
375  uint32_t length;
376  uint32_t offset = 1;
377  int esc_count = src[0];
378  GetBitContext gb;
379  lag_rac rac;
380  const uint8_t *src_end = src + src_size;
381 
382  rac.avctx = l->avctx;
383  l->zeros = 0;
384 
385  if (esc_count < 4) {
386  length = width * height;
387  if (esc_count && AV_RL32(src + 1) < length) {
388  length = AV_RL32(src + 1);
389  offset += 4;
390  }
391 
392  init_get_bits(&gb, src + offset, src_size * 8);
393 
394  if (lag_read_prob_header(&rac, &gb) < 0)
395  return -1;
396 
397  lag_rac_init(&rac, &gb, length - stride);
398 
399  for (i = 0; i < height; i++)
400  read += lag_decode_line(l, &rac, dst + (i * stride), width,
401  stride, esc_count);
402 
403  if (read > length)
405  "Output more bytes than length (%d of %d)\n", read,
406  length);
407  } else if (esc_count < 8) {
408  esc_count -= 4;
409  if (esc_count > 0) {
410  /* Zero run coding only, no range coding. */
411  for (i = 0; i < height; i++) {
412  int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
413  src_end, width, esc_count);
414  if (res < 0)
415  return res;
416  src += res;
417  }
418  } else {
419  if (src_size < width * height)
420  return AVERROR_INVALIDDATA; // buffer not big enough
421  /* Plane is stored uncompressed */
422  for (i = 0; i < height; i++) {
423  memcpy(dst + (i * stride), src, width);
424  src += width;
425  }
426  }
427  } else if (esc_count == 0xff) {
428  /* Plane is a solid run of given value */
429  for (i = 0; i < height; i++)
430  memset(dst + i * stride, src[1], width);
431  /* Do not apply prediction.
432  Note: memset to 0 above, setting first value to src[1]
433  and applying prediction gives the same result. */
434  return 0;
435  } else {
437  "Invalid zero run escape code! (%#x)\n", esc_count);
438  return -1;
439  }
440 
441  for (i = 0; i < height; i++) {
442  lag_pred_line(l, dst, width, stride, i);
443  dst += stride;
444  }
445 
446  return 0;
447 }
448 
458  void *data, int *data_size, AVPacket *avpkt)
459 {
460  const uint8_t *buf = avpkt->data;
461  int buf_size = avpkt->size;
462  LagarithContext *l = avctx->priv_data;
463  AVFrame *const p = &l->picture;
464  uint8_t frametype = 0;
465  uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
466  int offs[4];
467  uint8_t *srcs[4], *dst;
468  int i, j, planes = 3;
469 
470  AVFrame *picture = data;
471 
472  if (p->data[0])
473  avctx->release_buffer(avctx, p);
474 
475  p->reference = 0;
476  p->key_frame = 1;
477 
478  frametype = buf[0];
479 
480  offset_gu = AV_RL32(buf + 1);
481  offset_bv = AV_RL32(buf + 5);
482 
483  switch (frametype) {
484  case FRAME_SOLID_RGBA:
485  avctx->pix_fmt = PIX_FMT_RGB32;
486 
487  if (avctx->get_buffer(avctx, p) < 0) {
488  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
489  return -1;
490  }
491 
492  dst = p->data[0];
493  for (j = 0; j < avctx->height; j++) {
494  for (i = 0; i < avctx->width; i++)
495  AV_WN32(dst + i * 4, offset_gu);
496  dst += p->linesize[0];
497  }
498  break;
499  case FRAME_ARITH_RGBA:
500  avctx->pix_fmt = PIX_FMT_RGB32;
501  planes = 4;
502  offset_ry += 4;
503  offs[3] = AV_RL32(buf + 9);
504  case FRAME_ARITH_RGB24:
505  if (frametype == FRAME_ARITH_RGB24)
506  avctx->pix_fmt = PIX_FMT_RGB24;
507 
508  if (avctx->get_buffer(avctx, p) < 0) {
509  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
510  return -1;
511  }
512 
513  offs[0] = offset_bv;
514  offs[1] = offset_gu;
515  offs[2] = offset_ry;
516 
517  l->rgb_stride = FFALIGN(avctx->width, 16);
519  l->rgb_stride * avctx->height * planes + 1);
520  if (!l->rgb_planes) {
521  av_log(avctx, AV_LOG_ERROR, "cannot allocate temporary buffer\n");
522  return AVERROR(ENOMEM);
523  }
524  for (i = 0; i < planes; i++)
525  srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
526  if (offset_ry >= buf_size ||
527  offset_gu >= buf_size ||
528  offset_bv >= buf_size ||
529  (planes == 4 && offs[3] >= buf_size)) {
530  av_log(avctx, AV_LOG_ERROR,
531  "Invalid frame offsets\n");
532  return AVERROR_INVALIDDATA;
533  }
534  for (i = 0; i < planes; i++)
535  lag_decode_arith_plane(l, srcs[i],
536  avctx->width, avctx->height,
537  -l->rgb_stride, buf + offs[i],
538  buf_size - offs[i]);
539  dst = p->data[0];
540  for (i = 0; i < planes; i++)
541  srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
542  for (j = 0; j < avctx->height; j++) {
543  for (i = 0; i < avctx->width; i++) {
544  uint8_t r, g, b, a;
545  r = srcs[0][i];
546  g = srcs[1][i];
547  b = srcs[2][i];
548  r += g;
549  b += g;
550  if (frametype == FRAME_ARITH_RGBA) {
551  a = srcs[3][i];
552  AV_WN32(dst + i * 4, MKBETAG(a, r, g, b));
553  } else {
554  dst[i * 3 + 0] = r;
555  dst[i * 3 + 1] = g;
556  dst[i * 3 + 2] = b;
557  }
558  }
559  dst += p->linesize[0];
560  for (i = 0; i < planes; i++)
561  srcs[i] += l->rgb_stride;
562  }
563  break;
564  case FRAME_ARITH_YV12:
565  avctx->pix_fmt = PIX_FMT_YUV420P;
566 
567  if (avctx->get_buffer(avctx, p) < 0) {
568  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
569  return -1;
570  }
571 
572  if (offset_ry >= buf_size ||
573  offset_gu >= buf_size ||
574  offset_bv >= buf_size) {
575  av_log(avctx, AV_LOG_ERROR,
576  "Invalid frame offsets\n");
577  return AVERROR_INVALIDDATA;
578  }
579 
580  lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
581  p->linesize[0], buf + offset_ry,
582  buf_size - offset_ry);
583  lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
584  avctx->height / 2, p->linesize[2],
585  buf + offset_gu, buf_size - offset_gu);
586  lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
587  avctx->height / 2, p->linesize[1],
588  buf + offset_bv, buf_size - offset_bv);
589  break;
590  default:
591  av_log(avctx, AV_LOG_ERROR,
592  "Unsupported Lagarith frame type: %#x\n", frametype);
593  return -1;
594  }
595 
596  *picture = *p;
597  *data_size = sizeof(AVFrame);
598 
599  return buf_size;
600 }
601 
603 {
604  LagarithContext *l = avctx->priv_data;
605  l->avctx = avctx;
606 
607  dsputil_init(&l->dsp, avctx);
608 
609  return 0;
610 }
611 
613 {
614  LagarithContext *l = avctx->priv_data;
615 
616  if (l->picture.data[0])
617  avctx->release_buffer(avctx, &l->picture);
618  av_freep(&l->rgb_planes);
619 
620  return 0;
621 }
622 
624  .name = "lagarith",
625  .type = AVMEDIA_TYPE_VIDEO,
626  .id = CODEC_ID_LAGARITH,
627  .priv_data_size = sizeof(LagarithContext),
631  .capabilities = CODEC_CAP_DR1,
632  .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
633 };