FFmpeg
qdrw.c
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1 /*
2  * QuickDraw (qdrw) codec
3  * Copyright (c) 2004 Konstantin Shishkov
4  * Copyright (c) 2015 Vittorio Giovara
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * Apple QuickDraw codec.
26  * https://developer.apple.com/legacy/library/documentation/mac/QuickDraw/QuickDraw-461.html
27  */
28 
29 #include "libavutil/common.h"
30 #include "libavutil/intreadwrite.h"
31 #include "avcodec.h"
32 #include "bytestream.h"
33 #include "internal.h"
34 
36  CLIP = 0x0001,
37  PACKBITSRECT = 0x0098,
41  SHORTCOMMENT = 0x00A0,
43 
44  EOP = 0x00FF,
45 };
46 
48  uint32_t *pal, int colors, int pixmap)
49 {
50  int i;
51 
52  for (i = 0; i <= colors; i++) {
53  uint8_t r, g, b;
54  unsigned int idx = bytestream2_get_be16(gbc); /* color index */
55  if (idx > 255 && !pixmap) {
56  av_log(avctx, AV_LOG_WARNING,
57  "Palette index out of range: %u\n", idx);
58  bytestream2_skip(gbc, 6);
59  continue;
60  }
61  if (avctx->pix_fmt != AV_PIX_FMT_PAL8)
62  return AVERROR_INVALIDDATA;
63  r = bytestream2_get_byte(gbc);
64  bytestream2_skip(gbc, 1);
65  g = bytestream2_get_byte(gbc);
66  bytestream2_skip(gbc, 1);
67  b = bytestream2_get_byte(gbc);
68  bytestream2_skip(gbc, 1);
69  pal[pixmap ? i : idx] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
70  }
71  return 0;
72 }
73 
75 {
76  int offset = avctx->width;
77  uint8_t *outdata = p->data[0];
78  int i, j;
79 
80  for (i = 0; i < avctx->height; i++) {
81  int size, left, code, pix;
82  uint8_t *out = outdata;
83  int pos = 0;
84 
85  /* size of packed line */
86  if (offset / 4 > 200)
87  size = left = bytestream2_get_be16(gbc);
88  else
89  size = left = bytestream2_get_byte(gbc);
90  if (bytestream2_get_bytes_left(gbc) < size)
91  return AVERROR_INVALIDDATA;
92 
93  /* decode line */
94  while (left > 0) {
95  code = bytestream2_get_byte(gbc);
96  if (code & 0x80 ) { /* run */
97  pix = bytestream2_get_byte(gbc);
98  for (j = 0; j < 257 - code; j++) {
99  if (pos < offset)
100  out[pos++] = (pix & 0xC0) >> 6;
101  if (pos < offset)
102  out[pos++] = (pix & 0x30) >> 4;
103  if (pos < offset)
104  out[pos++] = (pix & 0x0C) >> 2;
105  if (pos < offset)
106  out[pos++] = (pix & 0x03);
107  }
108  left -= 2;
109  } else { /* copy */
110  for (j = 0; j < code + 1; j++) {
111  pix = bytestream2_get_byte(gbc);
112  if (pos < offset)
113  out[pos++] = (pix & 0xC0) >> 6;
114  if (pos < offset)
115  out[pos++] = (pix & 0x30) >> 4;
116  if (pos < offset)
117  out[pos++] = (pix & 0x0C) >> 2;
118  if (pos < offset)
119  out[pos++] = (pix & 0x03);
120  }
121  left -= 1 + (code + 1);
122  }
123  }
124  outdata += p->linesize[0];
125  }
126  return 0;
127 }
128 
130 {
131  int offset = avctx->width;
132  uint8_t *outdata = p->data[0];
133  int i, j;
134 
135  for (i = 0; i < avctx->height; i++) {
136  int size, left, code, pix;
137  uint8_t *out = outdata;
138  int pos = 0;
139 
140  /* size of packed line */
141  size = left = bytestream2_get_be16(gbc);
142  if (bytestream2_get_bytes_left(gbc) < size)
143  return AVERROR_INVALIDDATA;
144 
145  /* decode line */
146  while (left > 0) {
147  code = bytestream2_get_byte(gbc);
148  if (code & 0x80 ) { /* run */
149  pix = bytestream2_get_byte(gbc);
150  for (j = 0; j < 257 - code; j++) {
151  if (pos < offset)
152  out[pos++] = (pix & 0xF0) >> 4;
153  if (pos < offset)
154  out[pos++] = pix & 0xF;
155  }
156  left -= 2;
157  } else { /* copy */
158  for (j = 0; j < code + 1; j++) {
159  pix = bytestream2_get_byte(gbc);
160  if (pos < offset)
161  out[pos++] = (pix & 0xF0) >> 4;
162  if (pos < offset)
163  out[pos++] = pix & 0xF;
164  }
165  left -= 1 + (code + 1);
166  }
167  }
168  outdata += p->linesize[0];
169  }
170  return 0;
171 }
172 
173 static int decode_rle16(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc)
174 {
175  int offset = avctx->width;
176  uint8_t *outdata = p->data[0];
177  int i, j;
178 
179  for (i = 0; i < avctx->height; i++) {
180  int size, left, code, pix;
181  uint16_t *out = (uint16_t *)outdata;
182  int pos = 0;
183 
184  /* size of packed line */
185  size = left = bytestream2_get_be16(gbc);
186  if (bytestream2_get_bytes_left(gbc) < size)
187  return AVERROR_INVALIDDATA;
188 
189  /* decode line */
190  while (left > 0) {
191  code = bytestream2_get_byte(gbc);
192  if (code & 0x80 ) { /* run */
193  pix = bytestream2_get_be16(gbc);
194  for (j = 0; j < 257 - code; j++) {
195  if (pos < offset) {
196  out[pos++] = pix;
197  }
198  }
199  left -= 3;
200  } else { /* copy */
201  for (j = 0; j < code + 1; j++) {
202  if (pos < offset) {
203  out[pos++] = bytestream2_get_be16(gbc);
204  } else {
205  bytestream2_skip(gbc, 2);
206  }
207  }
208  left -= 1 + (code + 1) * 2;
209  }
210  }
211  outdata += p->linesize[0];
212  }
213  return 0;
214 }
215 
216 static int decode_rle(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc,
217  int step)
218 {
219  int i, j;
220  int offset = avctx->width * step;
221  uint8_t *outdata = p->data[0];
222 
223  for (i = 0; i < avctx->height; i++) {
224  int size, left, code, pix;
225  uint8_t *out = outdata;
226  int pos = 0;
227 
228  /* size of packed line */
229  size = left = bytestream2_get_be16(gbc);
230  if (bytestream2_get_bytes_left(gbc) < size)
231  return AVERROR_INVALIDDATA;
232 
233  /* decode line */
234  while (left > 0) {
235  code = bytestream2_get_byte(gbc);
236  if (code & 0x80 ) { /* run */
237  pix = bytestream2_get_byte(gbc);
238  for (j = 0; j < 257 - code; j++) {
239  if (pos < offset)
240  out[pos] = pix;
241  pos += step;
242  if (pos >= offset && step > 1) {
243  pos -= offset;
244  pos++;
245  }
246  }
247  left -= 2;
248  } else { /* copy */
249  for (j = 0; j < code + 1; j++) {
250  pix = bytestream2_get_byte(gbc);
251  if (pos < offset)
252  out[pos] = pix;
253  pos += step;
254  if (pos >= offset && step > 1) {
255  pos -= offset;
256  pos++;
257  }
258  }
259  left -= 2 + code;
260  }
261  }
262  outdata += p->linesize[0];
263  }
264  return 0;
265 }
266 
267 static int check_header(const char *buf, int buf_size)
268 {
269  unsigned w, h, v0, v1;
270 
271  if (buf_size < 40)
272  return 0;
273 
274  w = AV_RB16(buf+6);
275  h = AV_RB16(buf+8);
276  v0 = AV_RB16(buf+10);
277  v1 = AV_RB16(buf+12);
278 
279  if (!w || !h)
280  return 0;
281 
282  if (v0 == 0x1101)
283  return 1;
284  if (v0 == 0x0011 && v1 == 0x02FF)
285  return 2;
286  return 0;
287 }
288 
289 
290 static int decode_frame(AVCodecContext *avctx,
291  void *data, int *got_frame,
292  AVPacket *avpkt)
293 {
294  AVFrame * const p = data;
295  GetByteContext gbc;
296  int colors;
297  int w, h, ret;
298  int ver;
299 
300  bytestream2_init(&gbc, avpkt->data, avpkt->size);
301  if ( bytestream2_get_bytes_left(&gbc) >= 552
302  && check_header(gbc.buffer + 512, bytestream2_get_bytes_left(&gbc) - 512)
303  )
304  bytestream2_skip(&gbc, 512);
305 
307 
308  /* smallest PICT header */
309  if (bytestream2_get_bytes_left(&gbc) < 40) {
310  av_log(avctx, AV_LOG_ERROR, "Frame is too small %d\n",
312  return AVERROR_INVALIDDATA;
313  }
314 
315  bytestream2_skip(&gbc, 6);
316  h = bytestream2_get_be16(&gbc);
317  w = bytestream2_get_be16(&gbc);
318 
319  ret = ff_set_dimensions(avctx, w, h);
320  if (ret < 0)
321  return ret;
322 
323  /* version 1 is identified by 0x1101
324  * it uses byte-aligned opcodes rather than word-aligned */
325  if (ver == 1) {
326  avpriv_request_sample(avctx, "QuickDraw version 1");
327  return AVERROR_PATCHWELCOME;
328  } else if (ver != 2) {
329  avpriv_request_sample(avctx, "QuickDraw version unknown (%X)", bytestream2_get_be32(&gbc));
330  return AVERROR_PATCHWELCOME;
331  }
332 
333  bytestream2_skip(&gbc, 4+26);
334 
335  while (bytestream2_get_bytes_left(&gbc) >= 4) {
336  int bppcnt, bpp;
337  int rowbytes, pack_type;
338  int flags;
339  int opcode = bytestream2_get_be16(&gbc);
340 
341  switch(opcode) {
342  case CLIP:
343  bytestream2_skip(&gbc, 10);
344  break;
345  case PACKBITSRECT:
346  case PACKBITSRGN:
347  av_log(avctx, AV_LOG_DEBUG, "Parsing Packbit opcode\n");
348 
349  flags = bytestream2_get_be16(&gbc) & 0xC000;
350  bytestream2_skip(&gbc, 28);
351  bppcnt = bytestream2_get_be16(&gbc); /* cmpCount */
352  bpp = bytestream2_get_be16(&gbc); /* cmpSize */
353 
354  av_log(avctx, AV_LOG_DEBUG, "bppcount %d bpp %d\n", bppcnt, bpp);
355  if (bppcnt == 1 && bpp == 8) {
356  avctx->pix_fmt = AV_PIX_FMT_PAL8;
357  } else if (bppcnt == 1 && (bpp == 4 || bpp == 2)) {
358  avctx->pix_fmt = AV_PIX_FMT_PAL8;
359  } else if (bppcnt == 3 && bpp == 5) {
360  avctx->pix_fmt = AV_PIX_FMT_RGB555;
361  } else {
362  av_log(avctx, AV_LOG_ERROR,
363  "Invalid pixel format (bppcnt %d bpp %d) in Packbit\n",
364  bppcnt, bpp);
365  return AVERROR_INVALIDDATA;
366  }
367 
368  /* jump to palette */
369  bytestream2_skip(&gbc, 18);
370  colors = bytestream2_get_be16(&gbc);
371 
372  if (colors < 0 || colors > 256) {
373  av_log(avctx, AV_LOG_ERROR,
374  "Error color count - %i(0x%X)\n", colors, colors);
375  return AVERROR_INVALIDDATA;
376  }
377  if (bytestream2_get_bytes_left(&gbc) < (colors + 1) * 8) {
378  av_log(avctx, AV_LOG_ERROR, "Palette is too small %d\n",
380  return AVERROR_INVALIDDATA;
381  }
382  if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
383  return ret;
384 
385  ret = parse_palette(avctx, &gbc, (uint32_t *)p->data[1], colors, flags & 0x8000);
386  if (ret < 0)
387  return ret;
388  p->palette_has_changed = 1;
389 
390  /* jump to image data */
391  bytestream2_skip(&gbc, 18);
392 
393  if (opcode == PACKBITSRGN) {
394  bytestream2_skip(&gbc, 2 + 8); /* size + rect */
395  avpriv_report_missing_feature(avctx, "Packbit mask region");
396  }
397 
398  if (avctx->pix_fmt == AV_PIX_FMT_RGB555)
399  ret = decode_rle16(avctx, p, &gbc);
400  else if (bpp == 2)
401  ret = decode_rle_bpp2(avctx, p, &gbc);
402  else if (bpp == 4)
403  ret = decode_rle_bpp4(avctx, p, &gbc);
404  else
405  ret = decode_rle(avctx, p, &gbc, bppcnt);
406  if (ret < 0)
407  return ret;
408  *got_frame = 1;
409  break;
410  case DIRECTBITSRECT:
411  case DIRECTBITSRGN:
412  av_log(avctx, AV_LOG_DEBUG, "Parsing Directbit opcode\n");
413 
414  bytestream2_skip(&gbc, 4);
415  rowbytes = bytestream2_get_be16(&gbc) & 0x3FFF;
416  if (rowbytes <= 250) {
417  avpriv_report_missing_feature(avctx, "Short rowbytes");
418  return AVERROR_PATCHWELCOME;
419  }
420 
421  bytestream2_skip(&gbc, 4);
422  h = bytestream2_get_be16(&gbc);
423  w = bytestream2_get_be16(&gbc);
424  bytestream2_skip(&gbc, 2);
425 
426  ret = ff_set_dimensions(avctx, w, h);
427  if (ret < 0)
428  return ret;
429 
430  pack_type = bytestream2_get_be16(&gbc);
431 
432  bytestream2_skip(&gbc, 16);
433  bppcnt = bytestream2_get_be16(&gbc); /* cmpCount */
434  bpp = bytestream2_get_be16(&gbc); /* cmpSize */
435 
436  av_log(avctx, AV_LOG_DEBUG, "bppcount %d bpp %d\n", bppcnt, bpp);
437  if (bppcnt == 3 && bpp == 8) {
438  avctx->pix_fmt = AV_PIX_FMT_RGB24;
439  } else if (bppcnt == 3 && bpp == 5 || bppcnt == 2 && bpp == 8) {
440  avctx->pix_fmt = AV_PIX_FMT_RGB555;
441  } else if (bppcnt == 4 && bpp == 8) {
442  avctx->pix_fmt = AV_PIX_FMT_ARGB;
443  } else {
444  av_log(avctx, AV_LOG_ERROR,
445  "Invalid pixel format (bppcnt %d bpp %d) in Directbit\n",
446  bppcnt, bpp);
447  return AVERROR_INVALIDDATA;
448  }
449 
450  /* set packing when default is selected */
451  if (pack_type == 0)
452  pack_type = bppcnt;
453 
454  if (pack_type != 3 && pack_type != 4) {
455  avpriv_request_sample(avctx, "Pack type %d", pack_type);
456  return AVERROR_PATCHWELCOME;
457  }
458  if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
459  return ret;
460 
461  /* jump to data */
462  bytestream2_skip(&gbc, 30);
463 
464  if (opcode == DIRECTBITSRGN) {
465  bytestream2_skip(&gbc, 2 + 8); /* size + rect */
466  avpriv_report_missing_feature(avctx, "DirectBit mask region");
467  }
468 
469  if (avctx->pix_fmt == AV_PIX_FMT_RGB555)
470  ret = decode_rle16(avctx, p, &gbc);
471  else
472  ret = decode_rle(avctx, p, &gbc, bppcnt);
473  if (ret < 0)
474  return ret;
475  *got_frame = 1;
476  break;
477  case LONGCOMMENT:
478  bytestream2_get_be16(&gbc);
479  bytestream2_skip(&gbc, bytestream2_get_be16(&gbc));
480  break;
481  default:
482  av_log(avctx, AV_LOG_TRACE, "Unknown 0x%04X opcode\n", opcode);
483  break;
484  }
485  /* exit the loop when a known pixel block has been found */
486  if (*got_frame) {
487  int eop, trail;
488 
489  /* re-align to a word */
491 
492  eop = bytestream2_get_be16(&gbc);
493  trail = bytestream2_get_bytes_left(&gbc);
494  if (eop != EOP)
495  av_log(avctx, AV_LOG_WARNING,
496  "Missing end of picture opcode (found 0x%04X)\n", eop);
497  if (trail)
498  av_log(avctx, AV_LOG_WARNING, "Got %d trailing bytes\n", trail);
499  break;
500  }
501  }
502 
503  if (*got_frame) {
505  p->key_frame = 1;
506 
507  return avpkt->size;
508  } else {
509  av_log(avctx, AV_LOG_ERROR, "Frame contained no usable data\n");
510 
511  return AVERROR_INVALIDDATA;
512  }
513 }
514 
516  .name = "qdraw",
517  .long_name = NULL_IF_CONFIG_SMALL("Apple QuickDraw"),
518  .type = AVMEDIA_TYPE_VIDEO,
519  .id = AV_CODEC_ID_QDRAW,
520  .decode = decode_frame,
521  .capabilities = AV_CODEC_CAP_DR1,
522 };
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
This structure describes decoded (raw) audio or video data.
Definition: frame.h:268
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:68
int ff_set_dimensions(AVCodecContext *s, int width, int height)
Check that the provided frame dimensions are valid and set them on the codec context.
Definition: utils.c:104
const char * g
Definition: vf_curves.c:115
int size
Definition: avcodec.h:1478
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1775
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:133
Definition: qdrw.c:36
GLfloat v0
Definition: opengl_enc.c:106
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:87
AVCodec.
Definition: avcodec.h:3477
Definition: qdrw.c:44
void void avpriv_request_sample(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
uint8_t
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
AVCodec ff_qdraw_decoder
Definition: qdrw.c:515
#define AV_LOG_TRACE
Extremely verbose debugging, useful for libav* development.
Definition: log.h:202
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
uint8_t * data
Definition: avcodec.h:1477
const uint8_t * buffer
Definition: bytestream.h:34
ptrdiff_t size
Definition: opengl_enc.c:100
#define av_log(a,...)
static int decode_rle_bpp4(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc)
Definition: qdrw.c:129
#define U(x)
Definition: vp56_arith.h:37
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:260
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:164
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
const char * r
Definition: vf_curves.c:114
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
static av_always_inline unsigned int bytestream2_get_bytes_left(GetByteContext *g)
Definition: bytestream.h:154
static int decode_rle(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc, int step)
Definition: qdrw.c:216
const char * name
Name of the codec implementation.
Definition: avcodec.h:3484
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: qdrw.c:290
packed ARGB 8:8:8:8, 32bpp, ARGBARGB...
Definition: pixfmt.h:92
static int decode_rle16(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc)
Definition: qdrw.c:173
#define b
Definition: input.c:41
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:351
int width
picture width / height.
Definition: avcodec.h:1738
uint8_t w
Definition: llviddspenc.c:38
static int parse_palette(AVCodecContext *avctx, GetByteContext *gbc, uint32_t *pal, int colors, int pixmap)
Definition: qdrw.c:47
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:299
main external API structure.
Definition: avcodec.h:1565
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1964
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2]...the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so...,+,-,+,-,+,+,-,+,-,+,...hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32-hcoeff[1]-hcoeff[2]-...a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2}an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||.........intra?||||:Block01:yes no||||:Block02:.................||||:Block03::y DC::ref index:||||:Block04::cb DC::motion x:||||.........:cr DC::motion y:||||.................|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------------------------------|||Y subbands||Cb subbands||Cr subbands||||------||------||------|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||------||------||------||||------||------||------|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||------||------||------||||------||------||------|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||------||------||------||||------||------||------|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------------------------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction------------|\Dequantization-------------------\||Reference frames|\IDWT|--------------|Motion\|||Frame 0||Frame 1||Compensation.OBMC v-------|--------------|--------------.\------> Frame n output Frame Frame<----------------------------------/|...|-------------------Range Coder:============Binary Range Coder:-------------------The implemented range coder is an adapted version based upon"Range encoding: an algorithm for removing redundancy from a digitised message."by G.N.N.Martin.The symbols encoded by the Snow range coder are bits(0|1).The associated probabilities are not fix but change depending on the symbol mix seen so far.bit seen|new state---------+-----------------------------------------------0|256-state_transition_table[256-old_state];1|state_transition_table[old_state];state_transition_table={0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:-------------------------FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1.the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
Definition: snow.txt:206
void * buf
Definition: avisynth_c.h:766
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:425
void avpriv_report_missing_feature(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
#define flags(name, subs,...)
Definition: cbs_av1.c:561
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
QuickdrawOpcodes
Definition: qdrw.c:35
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:282
common internal api header.
common internal and external API header
static int decode_rle_bpp2(AVCodecContext *avctx, AVFrame *p, GetByteContext *gbc)
Definition: qdrw.c:74
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:375
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:346
static int check_header(const char *buf, int buf_size)
Definition: qdrw.c:267
FILE * out
Definition: movenc.c:54
This structure stores compressed data.
Definition: avcodec.h:1454
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:981
trying all byte sequences megabyte in length and selecting the best looking sequence will yield cases to try But a word about which is also called distortion Distortion can be quantified by almost any quality measurement one chooses the sum of squared differences is used but more complex methods that consider psychovisual effects can be used as well It makes no difference in this discussion First step