FFmpeg
sga.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2021 Paul B Mahol
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/avassert.h"
22 #include "libavutil/common.h"
23 #include "avcodec.h"
24 #include "get_bits.h"
25 #include "bytestream.h"
26 #include "internal.h"
27 
28 #define PALDATA_FOLLOWS_TILEDATA 4
29 #define HAVE_COMPRESSED_TILEMAP 32
30 #define HAVE_TILEMAP 128
31 
32 typedef struct SGAVideoContext {
34 
44 
45  int flags;
46  int nb_pal;
47  int nb_tiles;
49  int shift;
50  int plus;
51  int swap;
52 
53  uint32_t pal[256];
54  uint8_t *tileindex_data;
55  unsigned tileindex_size;
56  uint8_t *palmapindex_data;
57  unsigned palmapindex_size;
58  uint8_t uncompressed[65536];
60 
62 {
63  avctx->pix_fmt = AV_PIX_FMT_PAL8;
64  return 0;
65 }
66 
67 static int decode_palette(GetByteContext *gb, uint32_t *pal)
68 {
69  GetBitContext gbit;
70 
71  if (bytestream2_get_bytes_left(gb) < 18)
72  return AVERROR_INVALIDDATA;
73 
74  memset(pal, 0, 16 * sizeof(*pal));
75  init_get_bits8(&gbit, gb->buffer, 18);
76 
77  for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
78  for (int index = 0; index < 16; index++) {
79  unsigned color = get_bits1(&gbit) << RGBIndex;
80  pal[15 - index] |= color << (5 + 16);
81  }
82  }
83 
84  for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
85  for (int index = 0; index < 16; index++) {
86  unsigned color = get_bits1(&gbit) << RGBIndex;
87  pal[15 - index] |= color << (5 + 8);
88  }
89  }
90 
91  for (int RGBIndex = 0; RGBIndex < 3; RGBIndex++) {
92  for (int index = 0; index < 16; index++) {
93  unsigned color = get_bits1(&gbit) << RGBIndex;
94  pal[15 - index] |= color << (5 + 0);
95  }
96  }
97 
98  for (int index = 0; index < 16; index++)
99  pal[index] = (0xFFU << 24) | pal[index] | (pal[index] >> 3);
100 
101  bytestream2_skip(gb, 18);
102 
103  return 0;
104 }
105 
107 {
108  const uint8_t *tt = s->tileindex_data;
109 
110  for (int y = 0; y < s->tiles_h; y++) {
111  for (int x = 0; x < s->tiles_w; x++) {
112  int pal_idx = s->palmapindex_data[y * s->tiles_w + x] * 16;
113  uint8_t *dst = frame->data[0] + y * 8 * frame->linesize[0] + x * 8;
114 
115  for (int yy = 0; yy < 8; yy++) {
116  for (int xx = 0; xx < 8; xx++)
117  dst[xx] = pal_idx + tt[xx];
118  tt += 8;
119 
120  dst += frame->linesize[0];
121  }
122  }
123  }
124 
125  return 0;
126 }
127 
129 {
130  GetByteContext *gb = &s->gb;
131  GetBitContext pm;
132 
133  bytestream2_seek(gb, s->tilemapdata_offset, SEEK_SET);
134  if (bytestream2_get_bytes_left(gb) < s->tilemapdata_size)
135  return AVERROR_INVALIDDATA;
136 
137  init_get_bits8(&pm, gb->buffer, s->tilemapdata_size);
138 
139  for (int y = 0; y < s->tiles_h; y++) {
140  for (int x = 0; x < s->tiles_w; x++) {
141  uint8_t tile[64];
142  int tilemap = get_bits(&pm, 16);
143  int flip_x = (tilemap >> 11) & 1;
144  int flip_y = (tilemap >> 12) & 1;
145  int tindex = av_clip((tilemap & 511) - 1, 0, s->nb_tiles - 1);
146  const uint8_t *tt = s->tileindex_data + tindex * 64;
147  int pal_idx = ((tilemap >> 13) & 3) * 16;
148  uint8_t *dst = frame->data[0] + y * 8 * frame->linesize[0] + x * 8;
149 
150  if (!flip_x && !flip_y) {
151  memcpy(tile, tt, 64);
152  } else if (flip_x && flip_y) {
153  for (int i = 0; i < 8; i++) {
154  for (int j = 0; j < 8; j++)
155  tile[i * 8 + j] = tt[(7 - i) * 8 + 7 - j];
156  }
157  } else if (flip_x) {
158  for (int i = 0; i < 8; i++) {
159  for (int j = 0; j < 8; j++)
160  tile[i * 8 + j] = tt[i * 8 + 7 - j];
161  }
162  } else {
163  for (int i = 0; i < 8; i++) {
164  for (int j = 0; j < 8; j++)
165  tile[i * 8 + j] = tt[(7 - i) * 8 + j];
166  }
167  }
168 
169  for (int yy = 0; yy < 8; yy++) {
170  for (int xx = 0; xx < 8; xx++)
171  dst[xx] = pal_idx + tile[xx + yy * 8];
172 
173  dst += frame->linesize[0];
174  }
175  }
176  }
177 
178  return 0;
179 }
180 
182 {
183  const uint8_t *src = s->tileindex_data;
184  uint8_t *dst = frame->data[0];
185 
186  for (int y = 0; y < frame->height; y += 8) {
187  for (int x = 0; x < frame->width; x += 8) {
188  for (int yy = 0; yy < 8; yy++) {
189  for (int xx = 0; xx < 8; xx++)
190  dst[x + xx + yy * frame->linesize[0]] = src[xx];
191  src += 8;
192  }
193  }
194 
195  dst += 8 * frame->linesize[0];
196  }
197 
198  return 0;
199 }
200 
201 static int lzss_decompress(AVCodecContext *avctx,
202  GetByteContext *gb, uint8_t *dst,
203  int dst_size, int shift, int plus)
204 {
205  int oi = 0;
206 
207  while (bytestream2_get_bytes_left(gb) > 0 && oi < dst_size) {
208  uint16_t displace, header = bytestream2_get_be16(gb);
209  int count, offset;
210 
211  for (int i = 0; i < 16; i++) {
212  switch (header >> 15) {
213  case 0:
214  if (oi + 2 < dst_size) {
215  dst[oi++] = bytestream2_get_byte(gb);
216  dst[oi++] = bytestream2_get_byte(gb);
217  }
218  break;
219  case 1:
220  displace = bytestream2_get_be16(gb);
221  count = displace >> shift;
222  offset = displace & ((1 << shift) - 1);
223 
224  if (displace == 0) {
225  while (bytestream2_get_bytes_left(gb) > 0 &&
226  oi < dst_size)
227  dst[oi++] = bytestream2_get_byte(gb);
228  return oi;
229  }
230 
231  count += plus;
232 
233  if (offset <= 0)
234  offset = 1;
235  if (oi < offset || oi + count * 2 > dst_size)
236  return AVERROR_INVALIDDATA;
237  for (int j = 0; j < count * 2; j++) {
238  dst[oi] = dst[oi - offset];
239  oi++;
240  }
241  break;
242  }
243 
244  header <<= 1;
245  }
246  }
247 
248  return AVERROR_INVALIDDATA;
249 }
250 
252 {
253  SGAVideoContext *s = avctx->priv_data;
254  const int bits = (s->nb_pal + 1) / 2;
255  GetByteContext *gb = &s->gb;
256  GetBitContext pm;
257 
258  bytestream2_seek(gb, s->palmapdata_offset, SEEK_SET);
259  if (bytestream2_get_bytes_left(gb) < s->palmapdata_size)
260  return AVERROR_INVALIDDATA;
261  init_get_bits8(&pm, gb->buffer, s->palmapdata_size);
262 
263  for (int y = 0; y < s->tiles_h; y++) {
264  uint8_t *dst = s->palmapindex_data + y * s->tiles_w;
265 
266  for (int x = 0; x < s->tiles_w; x++)
267  dst[x] = get_bits(&pm, bits);
268 
269  dst += s->tiles_w;
270  }
271 
272  return 0;
273 }
274 
275 static int decode_tiledata(AVCodecContext *avctx)
276 {
277  SGAVideoContext *s = avctx->priv_data;
278  GetByteContext *gb = &s->gb;
279  GetBitContext tm;
280 
281  bytestream2_seek(gb, s->tiledata_offset, SEEK_SET);
282  if (bytestream2_get_bytes_left(gb) < s->tiledata_size)
283  return AVERROR_INVALIDDATA;
284  init_get_bits8(&tm, gb->buffer, s->tiledata_size);
285 
286  for (int n = 0; n < s->nb_tiles; n++) {
287  uint8_t *dst = s->tileindex_data + n * 64;
288 
289  for (int yy = 0; yy < 8; yy++) {
290  for (int xx = 0; xx < 8; xx++)
291  dst[xx] = get_bits(&tm, 4);
292 
293  dst += 8;
294  }
295  }
296 
297  for (int i = 0; i < s->nb_tiles && s->swap; i++) {
298  uint8_t *dst = s->tileindex_data + i * 64;
299 
300  for (int j = 8; j < 64; j += 16) {
301  for (int k = 0; k < 8; k += 2)
302  FFSWAP(uint8_t, dst[j + k], dst[j+k+1]);
303  }
304  }
305 
306  return 0;
307 }
308 
309 static int sga_decode_frame(AVCodecContext *avctx, void *data,
310  int *got_frame, AVPacket *avpkt)
311 {
312  SGAVideoContext *s = avctx->priv_data;
313  GetByteContext *gb = &s->gb;
314  AVFrame *frame = data;
315  int ret, type;
316 
317  if (avpkt->size <= 14)
318  return AVERROR_INVALIDDATA;
319 
320  s->flags = avpkt->data[8];
321  s->nb_pal = avpkt->data[9];
322  s->tiles_w = avpkt->data[10];
323  s->tiles_h = avpkt->data[11];
324 
325  if (s->nb_pal > 4)
326  return AVERROR_INVALIDDATA;
327 
328  if ((ret = ff_set_dimensions(avctx,
329  s->tiles_w * 8,
330  s->tiles_h * 8)) < 0)
331  return ret;
332 
333  av_fast_padded_malloc(&s->tileindex_data, &s->tileindex_size,
334  avctx->width * avctx->height);
335  if (!s->tileindex_data)
336  return AVERROR(ENOMEM);
337 
338  av_fast_padded_malloc(&s->palmapindex_data, &s->palmapindex_size,
339  s->tiles_w * s->tiles_h);
340  if (!s->palmapindex_data)
341  return AVERROR(ENOMEM);
342 
343  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
344  return ret;
345 
346  bytestream2_init(gb, avpkt->data, avpkt->size);
347 
348  type = bytestream2_get_byte(gb);
349  s->metadata_size = 12 + ((!!(s->flags & HAVE_TILEMAP)) * 2);
350  s->nb_tiles = s->flags & HAVE_TILEMAP ? AV_RB16(avpkt->data + 12) : s->tiles_w * s->tiles_h;
351  if (s->nb_tiles > s->tiles_w * s->tiles_h)
352  return AVERROR_INVALIDDATA;
353 
354  av_log(avctx, AV_LOG_DEBUG, "type: %X flags: %X nb_tiles: %d\n", type, s->flags, s->nb_tiles);
355 
356  switch (type) {
357  case 0xE7:
358  case 0xCB:
359  case 0xCD:
360  s->swap = 1;
361  s->shift = 12;
362  s->plus = 1;
363  break;
364  case 0xC9:
365  s->swap = 1;
366  s->shift = 13;
367  s->plus = 1;
368  break;
369  case 0xC8:
370  s->swap = 1;
371  s->shift = 13;
372  s->plus = 0;
373  break;
374  case 0xC7:
375  s->swap = 0;
376  s->shift = 13;
377  s->plus = 1;
378  break;
379  case 0xC6:
380  s->swap = 0;
381  s->shift = 13;
382  s->plus = 0;
383  break;
384  }
385 
386  if (type == 0xE7) {
387  int offset = s->metadata_size, left;
388  int sizes[3];
389 
390  bytestream2_seek(gb, s->metadata_size, SEEK_SET);
391 
392  for (int i = 0; i < 3; i++)
393  sizes[i] = bytestream2_get_be16(gb);
394 
395  for (int i = 0; i < 3; i++) {
396  int size = sizes[i];
397  int raw = size >> 15;
398 
399  size &= (1 << 15) - 1;
400 
401  if (raw) {
403  return AVERROR_INVALIDDATA;
404 
405  if (sizeof(s->uncompressed) - offset < size)
406  return AVERROR_INVALIDDATA;
407 
408  memcpy(s->uncompressed + offset, gb->buffer, size);
409  bytestream2_skip(gb, size);
410  } else {
411  GetByteContext gb2;
412 
414  return AVERROR_INVALIDDATA;
415 
416  bytestream2_init(&gb2, gb->buffer, size);
417  ret = lzss_decompress(avctx, &gb2, s->uncompressed + offset,
418  sizeof(s->uncompressed) - offset, s->shift, s->plus);
419  if (ret < 0)
420  return ret;
421  bytestream2_skip(gb, size);
422  size = ret;
423  }
424 
425  offset += size;
426  }
427 
429  if (sizeof(s->uncompressed) - offset < left)
430  return AVERROR_INVALIDDATA;
431 
432  bytestream2_get_buffer(gb, s->uncompressed + offset, left);
433 
434  offset += left;
435  bytestream2_init(gb, s->uncompressed, offset);
436  }
437 
438  switch (type) {
439  case 0xCD:
440  case 0xCB:
441  case 0xC9:
442  case 0xC8:
443  case 0xC7:
444  case 0xC6:
445  bytestream2_seek(gb, s->metadata_size, SEEK_SET);
446  ret = lzss_decompress(avctx, gb, s->uncompressed + s->metadata_size,
447  sizeof(s->uncompressed) - s->metadata_size, s->shift, s->plus);
448  if (ret < 0)
449  return ret;
450  bytestream2_init(gb, s->uncompressed, ret + s->metadata_size);
451  case 0xE7:
452  case 0xC1:
453  s->tiledata_size = s->nb_tiles * 32;
454  s->paldata_size = s->nb_pal * 18;
455  s->tiledata_offset = s->flags & PALDATA_FOLLOWS_TILEDATA ? s->metadata_size : s->metadata_size + s->paldata_size;
456  s->paldata_offset = s->flags & PALDATA_FOLLOWS_TILEDATA ? s->metadata_size + s->tiledata_size : s->metadata_size;
457  s->palmapdata_offset = (s->flags & HAVE_TILEMAP) ? -1 : s->paldata_offset + s->paldata_size;
458  s->palmapdata_size = (s->flags & HAVE_TILEMAP) || s->nb_pal < 2 ? 0 : (s->tiles_w * s->tiles_h * ((s->nb_pal + 1) / 2) + 7) / 8;
459  s->tilemapdata_size = (s->flags & HAVE_TILEMAP) ? s->tiles_w * s->tiles_h * 2 : 0;
460  s->tilemapdata_offset = (s->flags & HAVE_TILEMAP) ? s->paldata_offset + s->paldata_size: -1;
461 
462  bytestream2_seek(gb, s->paldata_offset, SEEK_SET);
463  for (int n = 0; n < s->nb_pal; n++) {
464  ret = decode_palette(gb, s->pal + 16 * n);
465  if (ret < 0)
466  return ret;
467  }
468 
469  if (s->tiledata_size > 0) {
470  ret = decode_tiledata(avctx);
471  if (ret < 0)
472  return ret;
473  }
474 
475  if (s->palmapdata_size > 0) {
476  ret = decode_palmapdata(avctx);
477  if (ret < 0)
478  return ret;
479  }
480 
481  if (s->palmapdata_size > 0 && s->tiledata_size > 0) {
483  if (ret < 0)
484  return ret;
485  } else if (s->tilemapdata_size > 0 && s->tiledata_size > 0) {
487  if (ret < 0)
488  return ret;
489  } else if (s->tiledata_size > 0) {
490  ret = decode_index(s, frame);
491  if (ret < 0)
492  return ret;
493  }
494  break;
495  default:
496  av_log(avctx, AV_LOG_ERROR, "Unknown type: %X\n", type);
497  return AVERROR_INVALIDDATA;
498  }
499 
500  memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
501  frame->palette_has_changed = 1;
502  frame->pict_type = AV_PICTURE_TYPE_I;
503  frame->key_frame = 1;
504 
505  *got_frame = 1;
506 
507  return avpkt->size;
508 }
509 
511 {
512  SGAVideoContext *s = avctx->priv_data;
513 
514  av_freep(&s->tileindex_data);
515  s->tileindex_size = 0;
516 
517  av_freep(&s->palmapindex_data);
518  s->palmapindex_size = 0;
519 
520  return 0;
521 }
522 
524  .name = "sga",
525  .long_name = NULL_IF_CONFIG_SMALL("Digital Pictures SGA Video"),
526  .type = AVMEDIA_TYPE_VIDEO,
527  .id = AV_CODEC_ID_SGA_VIDEO,
528  .priv_data_size = sizeof(SGAVideoContext),
531  .close = sga_decode_end,
532  .capabilities = AV_CODEC_CAP_DR1,
533  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
534 };
AVCodec
AVCodec.
Definition: codec.h:197
SGAVideoContext::tileindex_data
uint8_t * tileindex_data
Definition: sga.c:54
FF_CODEC_CAP_INIT_THREADSAFE
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
av_clip
#define av_clip
Definition: common.h:122
init
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
SGAVideoContext::palmapindex_size
unsigned palmapindex_size
Definition: sga.c:57
FFSWAP
#define FFSWAP(type, a, b)
Definition: common.h:108
color
Definition: vf_paletteuse.c:583
GetByteContext
Definition: bytestream.h:33
SGAVideoContext::pal
uint32_t pal[256]
Definition: sga.c:53
SGAVideoContext::nb_tiles
int nb_tiles
Definition: sga.c:47
bytestream2_seek
static av_always_inline int bytestream2_seek(GetByteContext *g, int offset, int whence)
Definition: bytestream.h:212
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
index
fg index
Definition: ffmpeg_filter.c:168
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:365
data
const char data[16]
Definition: mxf.c:142
SGAVideoContext::tiles_w
int tiles_w
Definition: sga.c:48
SGAVideoContext::plus
int plus
Definition: sga.c:50
SGAVideoContext::tiledata_offset
int tiledata_offset
Definition: sga.c:37
lzss_decompress
static int lzss_decompress(AVCodecContext *avctx, GetByteContext *gb, uint8_t *dst, int dst_size, int shift, int plus)
Definition: sga.c:201
SGAVideoContext::tileindex_size
unsigned tileindex_size
Definition: sga.c:55
bytestream2_skip
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:168
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:380
SGAVideoContext::metadata_size
int metadata_size
Definition: sga.c:35
GetBitContext
Definition: get_bits.h:62
sga_decode_frame
static int sga_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: sga.c:309
type
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 type
Definition: writing_filters.txt:86
SGAVideoContext::tiledata_size
int tiledata_size
Definition: sga.c:36
sga_decode_end
static av_cold int sga_decode_end(AVCodecContext *avctx)
Definition: sga.c:510
HAVE_TILEMAP
#define HAVE_TILEMAP
Definition: sga.c:30
decode_palmapdata
static int decode_palmapdata(AVCodecContext *avctx)
Definition: sga.c:251
avassert.h
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
decode_tiledata
static int decode_tiledata(AVCodecContext *avctx)
Definition: sga.c:275
av_cold
#define av_cold
Definition: attributes.h:90
init_get_bits8
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:678
SGAVideoContext::gb
GetByteContext gb
Definition: sga.c:33
decode
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
s
#define s(width, name)
Definition: cbs_vp9.c:257
AV_CODEC_ID_SGA_VIDEO
@ AV_CODEC_ID_SGA_VIDEO
Definition: codec_id.h:309
GetByteContext::buffer
const uint8_t * buffer
Definition: bytestream.h:34
bits
uint8_t bits
Definition: vp3data.h:141
decode_index
static int decode_index(SGAVideoContext *s, AVFrame *frame)
Definition: sga.c:181
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:202
get_bits.h
sizes
static const int sizes[][2]
Definition: img2dec.c:53
AVPALETTE_SIZE
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:499
src
#define src
Definition: vp8dsp.c:255
bytestream2_get_buffer
static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g, uint8_t *dst, unsigned int size)
Definition: bytestream.h:267
SGAVideoContext::nb_pal
int nb_pal
Definition: sga.c:46
SGAVideoContext::palmapindex_data
uint8_t * palmapindex_data
Definition: sga.c:56
decode_palette
static int decode_palette(GetByteContext *gb, uint32_t *pal)
Definition: sga.c:67
bytestream2_get_bytes_left
static av_always_inline int bytestream2_get_bytes_left(GetByteContext *g)
Definition: bytestream.h:158
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1645
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:366
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
size
int size
Definition: twinvq_data.h:10344
header
static const uint8_t header[24]
Definition: sdr2.c:67
SGAVideoContext::flags
int flags
Definition: sga.c:45
offset
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
Definition: writing_filters.txt:86
PALDATA_FOLLOWS_TILEDATA
#define PALDATA_FOLLOWS_TILEDATA
Definition: sga.c:28
SGAVideoContext
Definition: sga.c:32
decode_index_palmap
static int decode_index_palmap(SGAVideoContext *s, AVFrame *frame)
Definition: sga.c:106
SGAVideoContext::tilemapdata_offset
int tilemapdata_offset
Definition: sga.c:39
SGAVideoContext::tilemapdata_size
int tilemapdata_size
Definition: sga.c:38
i
int i
Definition: input.c:407
SGAVideoContext::palmapdata_size
int palmapdata_size
Definition: sga.c:43
SGAVideoContext::swap
int swap
Definition: sga.c:51
common.h
decode_index_tilemap
static int decode_index_tilemap(SGAVideoContext *s, AVFrame *frame)
Definition: sga.c:128
av_fast_padded_malloc
void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size)
Same behaviour av_fast_malloc but the buffer has additional AV_INPUT_BUFFER_PADDING_SIZE at the end w...
Definition: utils.c:50
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:204
AVCodecContext::height
int height
Definition: avcodec.h:557
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:594
avcodec.h
SGAVideoContext::shift
int shift
Definition: sga.c:49
AV_PIX_FMT_PAL8
@ AV_PIX_FMT_PAL8
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
ret
ret
Definition: filter_design.txt:187
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
SGAVideoContext::palmapdata_offset
int palmapdata_offset
Definition: sga.c:42
left
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:386
AVCodecContext
main external API structure.
Definition: avcodec.h:384
SGAVideoContext::paldata_size
int paldata_size
Definition: sga.c:40
shift
static int shift(int a, int b)
Definition: sonic.c:83
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
ff_set_dimensions
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:86
ff_sga_decoder
const AVCodec ff_sga_decoder
Definition: sga.c:523
AVPacket
This structure stores compressed data.
Definition: packet.h:342
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:411
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:557
bytestream.h
bytestream2_init
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:137
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
SGAVideoContext::tiles_h
int tiles_h
Definition: sga.c:48
sga_decode_init
static av_cold int sga_decode_init(AVCodecContext *avctx)
Definition: sga.c:61
SGAVideoContext::uncompressed
uint8_t uncompressed[65536]
Definition: sga.c:58
AV_RB16
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:98
SGAVideoContext::paldata_offset
int paldata_offset
Definition: sga.c:41