Libav
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  s->frame = av_frame_alloc();
71  if (!s->frame)
72  return AVERROR(ENOMEM);
73 
74  return 0;
75 }
76 
78 {
79  unsigned i;
80  Escape124Context *s = avctx->priv_data;
81 
82  for (i = 0; i < 3; i++)
83  av_free(s->codebooks[i].blocks);
84 
85  av_frame_free(&s->frame);
86 
87  return 0;
88 }
89 
90 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
91  unsigned size)
92 {
93  unsigned i, j;
94  CodeBook cb = { 0 };
95 
96  if (!can_safely_read(gb, size * 34))
97  return cb;
98 
99  if (size >= INT_MAX / sizeof(MacroBlock))
100  return cb;
101  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
102  if (!cb.blocks)
103  return cb;
104 
105  cb.depth = depth;
106  cb.size = size;
107  for (i = 0; i < size; i++) {
108  unsigned mask_bits = get_bits(gb, 4);
109  unsigned color0 = get_bits(gb, 15);
110  unsigned color1 = get_bits(gb, 15);
111 
112  for (j = 0; j < 4; j++) {
113  if (mask_bits & (1 << j))
114  cb.blocks[i].pixels[j] = color1;
115  else
116  cb.blocks[i].pixels[j] = color0;
117  }
118  }
119  return cb;
120 }
121 
122 static unsigned decode_skip_count(GetBitContext* gb)
123 {
124  unsigned value;
125  // This function reads a maximum of 23 bits,
126  // which is within the padding space
127  if (!can_safely_read(gb, 1))
128  return -1;
129  value = get_bits1(gb);
130  if (!value)
131  return value;
132 
133  value += get_bits(gb, 3);
134  if (value != (1 + ((1 << 3) - 1)))
135  return value;
136 
137  value += get_bits(gb, 7);
138  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
139  return value;
140 
141  return value + get_bits(gb, 12);
142 }
143 
145  int* codebook_index, int superblock_index)
146 {
147  // This function reads a maximum of 22 bits; the callers
148  // guard this function appropriately
149  unsigned block_index, depth;
150 
151  if (get_bits1(gb)) {
152  static const char transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
153  *codebook_index = transitions[*codebook_index][get_bits1(gb)];
154  }
155 
156  depth = s->codebooks[*codebook_index].depth;
157 
158  // depth = 0 means that this shouldn't read any bits;
159  // in theory, this is the same as get_bits(gb, 0), but
160  // that doesn't actually work.
161  block_index = depth ? get_bits(gb, depth) : 0;
162 
163  if (*codebook_index == 1) {
164  block_index += superblock_index << s->codebooks[1].depth;
165  }
166 
167  // This condition can occur with invalid bitstreams and
168  // *codebook_index == 2
169  if (block_index >= s->codebooks[*codebook_index].size)
170  return (MacroBlock) { { 0 } };
171 
172  return s->codebooks[*codebook_index].blocks[block_index];
173 }
174 
175 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
176  // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
177  uint32_t *dst = sb->pixels32 + index + (index & -4);
178 
179  // This technically violates C99 aliasing rules, but it should be safe.
180  dst[0] = mb.pixels32[0];
181  dst[4] = mb.pixels32[1];
182 }
183 
184 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
185  uint16_t* src, unsigned src_stride)
186 {
187  unsigned y;
188  if (src)
189  for (y = 0; y < 8; y++)
190  memcpy(dest + y * dest_stride, src + y * src_stride,
191  sizeof(uint16_t) * 8);
192  else
193  for (y = 0; y < 8; y++)
194  memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
195 }
196 
197 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
198  0x4, 0x8, 0x40, 0x80,
199  0x100, 0x200, 0x1000, 0x2000,
200  0x400, 0x800, 0x4000, 0x8000};
201 
203  void *data, int *got_frame,
204  AVPacket *avpkt)
205 {
206  const uint8_t *buf = avpkt->data;
207  int buf_size = avpkt->size;
208  Escape124Context *s = avctx->priv_data;
209  AVFrame *frame = data;
210 
211  GetBitContext gb;
212  unsigned frame_flags, frame_size;
213  unsigned i;
214 
215  unsigned superblock_index, cb_index = 1,
216  superblock_col_index = 0,
217  superblocks_per_row = avctx->width / 8, skip = -1;
218 
219  uint16_t* old_frame_data, *new_frame_data;
220  unsigned old_stride, new_stride;
221  int ret;
222 
223  init_get_bits(&gb, buf, buf_size * 8);
224 
225  // This call also guards the potential depth reads for the
226  // codebook unpacking.
227  if (!can_safely_read(&gb, 64))
228  return -1;
229 
230  frame_flags = get_bits_long(&gb, 32);
231  frame_size = get_bits_long(&gb, 32);
232 
233  // Leave last frame unchanged
234  // FIXME: Is this necessary? I haven't seen it in any real samples
235  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
236  if (!s->frame->data[0])
237  return AVERROR_INVALIDDATA;
238 
239  av_log(NULL, AV_LOG_DEBUG, "Skipping frame\n");
240 
241  *got_frame = 1;
242  if ((ret = av_frame_ref(frame, s->frame)) < 0)
243  return ret;
244 
245  return frame_size;
246  }
247 
248  for (i = 0; i < 3; i++) {
249  if (frame_flags & (1 << (17 + i))) {
250  unsigned cb_depth, cb_size;
251  if (i == 2) {
252  // This codebook can be cut off at places other than
253  // powers of 2, leaving some of the entries undefined.
254  cb_size = get_bits_long(&gb, 20);
255  cb_depth = av_log2(cb_size - 1) + 1;
256  } else {
257  cb_depth = get_bits(&gb, 4);
258  if (i == 0) {
259  // This is the most basic codebook: pow(2,depth) entries
260  // for a depth-length key
261  cb_size = 1 << cb_depth;
262  } else {
263  // This codebook varies per superblock
264  // FIXME: I don't think this handles integer overflow
265  // properly
266  cb_size = s->num_superblocks << cb_depth;
267  }
268  }
269  av_free(s->codebooks[i].blocks);
270  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
271  if (!s->codebooks[i].blocks)
272  return -1;
273  }
274  }
275 
276  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0) {
277  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
278  return ret;
279  }
280 
281  new_frame_data = (uint16_t*)frame->data[0];
282  new_stride = frame->linesize[0] / 2;
283  old_frame_data = (uint16_t*)s->frame->data[0];
284  old_stride = s->frame->linesize[0] / 2;
285 
286  for (superblock_index = 0; superblock_index < s->num_superblocks;
287  superblock_index++) {
288  MacroBlock mb;
289  SuperBlock sb;
290  unsigned multi_mask = 0;
291 
292  if (skip == -1) {
293  // Note that this call will make us skip the rest of the blocks
294  // if the frame prematurely ends
295  skip = decode_skip_count(&gb);
296  }
297 
298  if (skip) {
299  copy_superblock(new_frame_data, new_stride,
300  old_frame_data, old_stride);
301  } else {
302  copy_superblock(sb.pixels, 8,
303  old_frame_data, old_stride);
304 
305  while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
306  unsigned mask;
307  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
308  mask = get_bits(&gb, 16);
309  multi_mask |= mask;
310  for (i = 0; i < 16; i++) {
311  if (mask & mask_matrix[i]) {
312  insert_mb_into_sb(&sb, mb, i);
313  }
314  }
315  }
316 
317  if (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
318  unsigned inv_mask = get_bits(&gb, 4);
319  for (i = 0; i < 4; i++) {
320  if (inv_mask & (1 << i)) {
321  multi_mask ^= 0xF << i*4;
322  } else {
323  multi_mask ^= get_bits(&gb, 4) << i*4;
324  }
325  }
326 
327  for (i = 0; i < 16; i++) {
328  if (multi_mask & mask_matrix[i]) {
329  if (!can_safely_read(&gb, 1))
330  break;
331  mb = decode_macroblock(s, &gb, &cb_index,
332  superblock_index);
333  insert_mb_into_sb(&sb, mb, i);
334  }
335  }
336  } else if (frame_flags & (1 << 16)) {
337  while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
338  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
339  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
340  }
341  }
342 
343  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
344  }
345 
346  superblock_col_index++;
347  new_frame_data += 8;
348  if (old_frame_data)
349  old_frame_data += 8;
350  if (superblock_col_index == superblocks_per_row) {
351  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
352  if (old_frame_data)
353  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
354  superblock_col_index = 0;
355  }
356  skip--;
357  }
358 
360  "Escape sizes: %i, %i, %i\n",
361  frame_size, buf_size, get_bits_count(&gb) / 8);
362 
363  av_frame_unref(s->frame);
364  if ((ret = av_frame_ref(s->frame, frame)) < 0)
365  return ret;
366 
367  *got_frame = 1;
368 
369  return frame_size;
370 }
371 
372 
374  .name = "escape124",
375  .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
376  .type = AVMEDIA_TYPE_VIDEO,
377  .id = AV_CODEC_ID_ESCAPE124,
378  .priv_data_size = sizeof(Escape124Context),
382  .capabilities = CODEC_CAP_DR1,
383 };
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:62
static const uint16_t mask_matrix[]
Definition: escape124.c:197
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:54
int size
This structure describes decoded (raw) audio or video data.
Definition: frame.h:135
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:240
int size
Definition: avcodec.h:974
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1270
unsigned size
Definition: escape124.c:40
AVCodec.
Definition: avcodec.h:2812
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:175
static int decode(MimicContext *ctx, int quality, int num_coeffs, int is_iframe)
Definition: mimic.c:275
uint8_t bits
Definition: crc.c:251
uint8_t
#define av_cold
Definition: attributes.h:66
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:57
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:122
int av_frame_ref(AVFrame *dst, const AVFrame *src)
Set up a new reference to the data described by the source frame.
Definition: frame.c:188
static void copy_superblock(uint16_t *dest, unsigned dest_stride, uint16_t *src, unsigned src_stride)
Definition: escape124.c:184
#define CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:684
const char data[16]
Definition: mxf.c:70
uint8_t * data
Definition: avcodec.h:973
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:194
uint32_t pixels32[2]
Definition: escape124.c:30
bitstream reader API header.
uint16_t pixels[4]
Definition: escape124.c:29
static const uint8_t frame_size[4]
Definition: g723_1_data.h:47
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:555
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:123
void av_free(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc(). ...
Definition: mem.c:186
static const uint16_t mask[17]
Definition: lzw.c:38
#define AVERROR(e)
Definition: error.h:43
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:69
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:145
CodeBook codebooks[3]
Definition: escape124.c:49
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:144
AVFrame * frame
Definition: escape124.c:45
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:169
const char * name
Name of the codec implementation.
Definition: avcodec.h:2819
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:77
int width
picture width / height.
Definition: avcodec.h:1229
AVCodec ff_escape124_decoder
Definition: escape124.c:373
MacroBlock * blocks
Definition: escape124.c:41
uint16_t pixels[64]
Definition: escape124.c:34
NULL
Definition: eval.c:55
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:153
main external API structure.
Definition: avcodec.h:1050
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:490
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:621
unsigned depth
Definition: escape124.c:39
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:271
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:90
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:375
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:304
unsigned num_superblocks
Definition: escape124.c:47
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:283
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:141
common internal api header.
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:231
static av_cold int init(AVCodecParserContext *s)
Definition: h264_parser.c:499
void * priv_data
Definition: avcodec.h:1092
#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:950
#define AV_GET_BUFFER_FLAG_REF
The decoder will keep a reference to the frame and may reuse it later.
Definition: avcodec.h:850
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:144
static int escape124_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:202