escape124.c
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1 /*
2  * Escape 124 Video Decoder
3  * Copyright (C) 2008 Eli Friedman (eli.friedman@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 
22 #include "avcodec.h"
23 #include "internal.h"
24 
25 #define BITSTREAM_READER_LE
26 #include "get_bits.h"
27 
28 typedef union MacroBlock {
29  uint16_t pixels[4];
30  uint32_t pixels32[2];
31 } MacroBlock;
32 
33 typedef union SuperBlock {
34  uint16_t pixels[64];
35  uint32_t pixels32[32];
36 } SuperBlock;
37 
38 typedef struct CodeBook {
39  unsigned depth;
40  unsigned size;
42 } CodeBook;
43 
44 typedef struct Escape124Context {
46 
47  unsigned num_superblocks;
48 
51 
52 static int can_safely_read(GetBitContext* gb, int bits) {
53  return get_bits_left(gb) >= bits;
54 }
55 
62 {
63  Escape124Context *s = avctx->priv_data;
64 
65  avctx->pix_fmt = AV_PIX_FMT_RGB555;
66 
67  s->num_superblocks = ((unsigned)avctx->width / 8) *
68  ((unsigned)avctx->height / 8);
69 
70  return 0;
71 }
72 
74 {
75  unsigned i;
76  Escape124Context *s = avctx->priv_data;
77 
78  for (i = 0; i < 3; i++)
79  av_free(s->codebooks[i].blocks);
80 
81  if (s->frame.data[0])
82  avctx->release_buffer(avctx, &s->frame);
83 
84  return 0;
85 }
86 
87 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
88  unsigned size)
89 {
90  unsigned i, j;
91  CodeBook cb = { 0 };
92 
93  if (!can_safely_read(gb, size * 34))
94  return cb;
95 
96  if (size >= INT_MAX / sizeof(MacroBlock))
97  return cb;
98  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
99  if (!cb.blocks)
100  return cb;
101 
102  cb.depth = depth;
103  cb.size = size;
104  for (i = 0; i < size; i++) {
105  unsigned mask_bits = get_bits(gb, 4);
106  unsigned color0 = get_bits(gb, 15);
107  unsigned color1 = get_bits(gb, 15);
108 
109  for (j = 0; j < 4; j++) {
110  if (mask_bits & (1 << j))
111  cb.blocks[i].pixels[j] = color1;
112  else
113  cb.blocks[i].pixels[j] = color0;
114  }
115  }
116  return cb;
117 }
118 
119 static unsigned decode_skip_count(GetBitContext* gb)
120 {
121  unsigned value;
122  // This function reads a maximum of 23 bits,
123  // which is within the padding space
124  if (!can_safely_read(gb, 1))
125  return -1;
126  value = get_bits1(gb);
127  if (!value)
128  return value;
129 
130  value += get_bits(gb, 3);
131  if (value != (1 + ((1 << 3) - 1)))
132  return value;
133 
134  value += get_bits(gb, 7);
135  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
136  return value;
137 
138  return value + get_bits(gb, 12);
139 }
140 
142  int* codebook_index, int superblock_index)
143 {
144  // This function reads a maximum of 22 bits; the callers
145  // guard this function appropriately
146  unsigned block_index, depth;
147 
148  if (get_bits1(gb)) {
149  static const char transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
150  *codebook_index = transitions[*codebook_index][get_bits1(gb)];
151  }
152 
153  depth = s->codebooks[*codebook_index].depth;
154 
155  // depth = 0 means that this shouldn't read any bits;
156  // in theory, this is the same as get_bits(gb, 0), but
157  // that doesn't actually work.
158  block_index = depth ? get_bits(gb, depth) : 0;
159 
160  if (*codebook_index == 1) {
161  block_index += superblock_index << s->codebooks[1].depth;
162  }
163 
164  // This condition can occur with invalid bitstreams and
165  // *codebook_index == 2
166  if (block_index >= s->codebooks[*codebook_index].size)
167  return (MacroBlock) { { 0 } };
168 
169  return s->codebooks[*codebook_index].blocks[block_index];
170 }
171 
172 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
173  // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
174  uint32_t *dst = sb->pixels32 + index + (index & -4);
175 
176  // This technically violates C99 aliasing rules, but it should be safe.
177  dst[0] = mb.pixels32[0];
178  dst[4] = mb.pixels32[1];
179 }
180 
181 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
182  uint16_t* src, unsigned src_stride)
183 {
184  unsigned y;
185  if (src)
186  for (y = 0; y < 8; y++)
187  memcpy(dest + y * dest_stride, src + y * src_stride,
188  sizeof(uint16_t) * 8);
189  else
190  for (y = 0; y < 8; y++)
191  memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
192 }
193 
194 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
195  0x4, 0x8, 0x40, 0x80,
196  0x100, 0x200, 0x1000, 0x2000,
197  0x400, 0x800, 0x4000, 0x8000};
198 
200  void *data, int *got_frame,
201  AVPacket *avpkt)
202 {
203  const uint8_t *buf = avpkt->data;
204  int buf_size = avpkt->size;
205  Escape124Context *s = avctx->priv_data;
206 
207  GetBitContext gb;
208  unsigned frame_flags, frame_size;
209  unsigned i;
210 
211  unsigned superblock_index, cb_index = 1,
212  superblock_col_index = 0,
213  superblocks_per_row = avctx->width / 8, skip = -1;
214 
215  uint16_t* old_frame_data, *new_frame_data;
216  unsigned old_stride, new_stride;
217 
218  AVFrame new_frame = { { 0 } };
219 
220  init_get_bits(&gb, buf, buf_size * 8);
221 
222  // This call also guards the potential depth reads for the
223  // codebook unpacking.
224  if (!can_safely_read(&gb, 64))
225  return -1;
226 
227  frame_flags = get_bits_long(&gb, 32);
228  frame_size = get_bits_long(&gb, 32);
229 
230  // Leave last frame unchanged
231  // FIXME: Is this necessary? I haven't seen it in any real samples
232  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
233  av_log(NULL, AV_LOG_DEBUG, "Skipping frame\n");
234 
235  *got_frame = 1;
236  *(AVFrame*)data = s->frame;
237 
238  return frame_size;
239  }
240 
241  for (i = 0; i < 3; i++) {
242  if (frame_flags & (1 << (17 + i))) {
243  unsigned cb_depth, cb_size;
244  if (i == 2) {
245  // This codebook can be cut off at places other than
246  // powers of 2, leaving some of the entries undefined.
247  cb_size = get_bits_long(&gb, 20);
248  cb_depth = av_log2(cb_size - 1) + 1;
249  } else {
250  cb_depth = get_bits(&gb, 4);
251  if (i == 0) {
252  // This is the most basic codebook: pow(2,depth) entries
253  // for a depth-length key
254  cb_size = 1 << cb_depth;
255  } else {
256  // This codebook varies per superblock
257  // FIXME: I don't think this handles integer overflow
258  // properly
259  cb_size = s->num_superblocks << cb_depth;
260  }
261  }
262  av_free(s->codebooks[i].blocks);
263  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
264  if (!s->codebooks[i].blocks)
265  return -1;
266  }
267  }
268 
269  new_frame.reference = 3;
270  if (ff_get_buffer(avctx, &new_frame)) {
271  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
272  return -1;
273  }
274 
275  new_frame_data = (uint16_t*)new_frame.data[0];
276  new_stride = new_frame.linesize[0] / 2;
277  old_frame_data = (uint16_t*)s->frame.data[0];
278  old_stride = s->frame.linesize[0] / 2;
279 
280  for (superblock_index = 0; superblock_index < s->num_superblocks;
281  superblock_index++) {
282  MacroBlock mb;
283  SuperBlock sb;
284  unsigned multi_mask = 0;
285 
286  if (skip == -1) {
287  // Note that this call will make us skip the rest of the blocks
288  // if the frame prematurely ends
289  skip = decode_skip_count(&gb);
290  }
291 
292  if (skip) {
293  copy_superblock(new_frame_data, new_stride,
294  old_frame_data, old_stride);
295  } else {
296  copy_superblock(sb.pixels, 8,
297  old_frame_data, old_stride);
298 
299  while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
300  unsigned mask;
301  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
302  mask = get_bits(&gb, 16);
303  multi_mask |= mask;
304  for (i = 0; i < 16; i++) {
305  if (mask & mask_matrix[i]) {
306  insert_mb_into_sb(&sb, mb, i);
307  }
308  }
309  }
310 
311  if (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
312  unsigned inv_mask = get_bits(&gb, 4);
313  for (i = 0; i < 4; i++) {
314  if (inv_mask & (1 << i)) {
315  multi_mask ^= 0xF << i*4;
316  } else {
317  multi_mask ^= get_bits(&gb, 4) << i*4;
318  }
319  }
320 
321  for (i = 0; i < 16; i++) {
322  if (multi_mask & mask_matrix[i]) {
323  if (!can_safely_read(&gb, 1))
324  break;
325  mb = decode_macroblock(s, &gb, &cb_index,
326  superblock_index);
327  insert_mb_into_sb(&sb, mb, i);
328  }
329  }
330  } else if (frame_flags & (1 << 16)) {
331  while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
332  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
333  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
334  }
335  }
336 
337  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
338  }
339 
340  superblock_col_index++;
341  new_frame_data += 8;
342  if (old_frame_data)
343  old_frame_data += 8;
344  if (superblock_col_index == superblocks_per_row) {
345  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
346  if (old_frame_data)
347  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
348  superblock_col_index = 0;
349  }
350  skip--;
351  }
352 
354  "Escape sizes: %i, %i, %i\n",
355  frame_size, buf_size, get_bits_count(&gb) / 8);
356 
357  if (s->frame.data[0])
358  avctx->release_buffer(avctx, &s->frame);
359 
360  *(AVFrame*)data = s->frame = new_frame;
361  *got_frame = 1;
362 
363  return frame_size;
364 }
365 
366 
368  .name = "escape124",
369  .type = AVMEDIA_TYPE_VIDEO,
370  .id = AV_CODEC_ID_ESCAPE124,
371  .priv_data_size = sizeof(Escape124Context),
375  .capabilities = CODEC_CAP_DR1,
376  .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
377 };
void * av_malloc(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:61
static const uint16_t mask_matrix[]
Definition: escape124.c:194
int size
This structure describes decoded (raw) audio or video data.
Definition: avcodec.h:989
AVFrame frame
Definition: escape124.c:45
void(* release_buffer)(struct AVCodecContext *c, AVFrame *pic)
Called to release buffers which were allocated with get_buffer.
Definition: avcodec.h:2259
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:237
int size
Definition: avcodec.h:916
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1533
union MacroBlock MacroBlock
union SuperBlock SuperBlock
unsigned size
Definition: escape124.c:40
AVCodec.
Definition: avcodec.h:2960
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:172
static int decode(MimicContext *ctx, int quality, int num_coeffs, int is_iframe)
Definition: mimic.c:228
uint8_t bits
Definition: crc.c:31
uint8_t
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:119
static void copy_superblock(uint16_t *dest, unsigned dest_stride, uint16_t *src, unsigned src_stride)
Definition: escape124.c:181
const char data[16]
Definition: mxf.c:66
uint8_t * data
Definition: avcodec.h:915
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:192
uint32_t pixels32[2]
Definition: escape124.c:30
bitstream reader API header.
uint16_t pixels[4]
Definition: escape124.c:29
static int init(AVCodecParserContext *s)
Definition: h264_parser.c:335
static const uint8_t frame_size[4]
Definition: g723_1_data.h:47
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:547
void av_free(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc(). ...
Definition: mem.c:139
static const uint16_t mask[17]
Definition: lzw.c:38
int reference
is this picture used as reference The values for this are the same as the MpegEncContext.picture_structure variable, that is 1->top field, 2->bottom field, 3->frame/both fields.
Definition: avcodec.h:1132
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:88
CodeBook codebooks[3]
Definition: escape124.c:49
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:146
const char * name
Name of the codec implementation.
Definition: avcodec.h:2967
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:73
struct CodeBook CodeBook
int width
picture width / height.
Definition: avcodec.h:1508
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame)
Get a buffer for a frame.
Definition: utils.c:464
AVCodec ff_escape124_decoder
Definition: escape124.c:367
struct Escape124Context Escape124Context
MacroBlock * blocks
Definition: escape124.c:41
uint16_t pixels[64]
Definition: escape124.c:34
NULL
Definition: eval.c:52
external API header
int linesize[AV_NUM_DATA_POINTERS]
Size, in bytes, of the data for each picture/channel plane.
Definition: avcodec.h:1008
main external API structure.
Definition: avcodec.h:1339
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:326
unsigned depth
Definition: escape124.c:39
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:268
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:87
int index
Definition: gxfenc.c:72
static int can_safely_read(GetBitContext *gb, int bits)
Definition: escape124.c:52
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:372
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:301
unsigned num_superblocks
Definition: escape124.c:47
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: avcodec.h:997
common internal api header.
void * priv_data
Definition: avcodec.h:1382
#define av_log2
Definition: intmath.h:85
uint32_t pixels32[32]
Definition: escape124.c:35
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:61
This structure stores compressed data.
Definition: avcodec.h:898
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:141
static int escape124_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:199