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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 FFmpeg.
6  *
7  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 /**
53  * Initialize the decoder
54  * @param avctx decoder context
55  * @return 0 success, negative on error
56  */
58 {
59  Escape124Context *s = avctx->priv_data;
60 
61  avctx->pix_fmt = AV_PIX_FMT_RGB555;
62 
63  s->num_superblocks = ((unsigned)avctx->width / 8) *
64  ((unsigned)avctx->height / 8);
65 
66  s->frame = av_frame_alloc();
67  if (!s->frame)
68  return AVERROR(ENOMEM);
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_freep(&s->codebooks[i].blocks);
80 
81  av_frame_free(&s->frame);
82 
83  return 0;
84 }
85 
87  unsigned size)
88 {
89  unsigned i, j;
90  CodeBook cb = { 0 };
91 
92  if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
93  return cb;
94 
95  if (size >= INT_MAX / sizeof(MacroBlock))
96  return cb;
97  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
98  if (!cb.blocks)
99  return cb;
100 
101  cb.depth = depth;
102  cb.size = size;
103  for (i = 0; i < size; i++) {
104  unsigned mask_bits = get_bits(gb, 4);
105  unsigned color0 = get_bits(gb, 15);
106  unsigned color1 = get_bits(gb, 15);
107 
108  for (j = 0; j < 4; j++) {
109  if (mask_bits & (1 << j))
110  cb.blocks[i].pixels[j] = color1;
111  else
112  cb.blocks[i].pixels[j] = color0;
113  }
114  }
115  return cb;
116 }
117 
118 static unsigned decode_skip_count(GetBitContext* gb)
119 {
120  unsigned value;
121  // This function reads a maximum of 23 bits,
122  // which is within the padding space
123  if (get_bits_left(gb) < 1)
124  return -1;
125  value = get_bits1(gb);
126  if (!value)
127  return value;
128 
129  value += get_bits(gb, 3);
130  if (value != (1 + ((1 << 3) - 1)))
131  return value;
132 
133  value += get_bits(gb, 7);
134  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
135  return value;
136 
137  return value + get_bits(gb, 12);
138 }
139 
141  int* codebook_index, int superblock_index)
142 {
143  // This function reads a maximum of 22 bits; the callers
144  // guard this function appropriately
145  unsigned block_index, depth;
146  int value = get_bits1(gb);
147  if (value) {
148  static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
149  value = get_bits1(gb);
150  *codebook_index = transitions[*codebook_index][value];
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 = get_bitsz(gb, depth);
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  int buf_size = avpkt->size;
204  Escape124Context *s = avctx->priv_data;
205  AVFrame *frame = 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  int ret;
219 
220  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
221  return ret;
222 
223  // This call also guards the potential depth reads for the
224  // codebook unpacking.
225  if (get_bits_left(&gb) < 64)
226  return -1;
227 
228  frame_flags = get_bits_long(&gb, 32);
229  frame_size = get_bits_long(&gb, 32);
230 
231  // Leave last frame unchanged
232  // FIXME: Is this necessary? I haven't seen it in any real samples
233  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
234  if (!s->frame->data[0])
235  return AVERROR_INVALIDDATA;
236 
237  av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
238 
239  *got_frame = 1;
240  if ((ret = av_frame_ref(frame, s->frame)) < 0)
241  return ret;
242 
243  return frame_size;
244  }
245 
246  for (i = 0; i < 3; i++) {
247  if (frame_flags & (1 << (17 + i))) {
248  unsigned cb_depth, cb_size;
249  if (i == 2) {
250  // This codebook can be cut off at places other than
251  // powers of 2, leaving some of the entries undefined.
252  cb_size = get_bits_long(&gb, 20);
253  cb_depth = av_log2(cb_size - 1) + 1;
254  } else {
255  cb_depth = get_bits(&gb, 4);
256  if (i == 0) {
257  // This is the most basic codebook: pow(2,depth) entries
258  // for a depth-length key
259  cb_size = 1 << cb_depth;
260  } else {
261  // This codebook varies per superblock
262  // FIXME: I don't think this handles integer overflow
263  // properly
264  cb_size = s->num_superblocks << cb_depth;
265  }
266  }
267  av_freep(&s->codebooks[i].blocks);
268  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
269  if (!s->codebooks[i].blocks)
270  return -1;
271  }
272  }
273 
274  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
275  return ret;
276 
277  new_frame_data = (uint16_t*)frame->data[0];
278  new_stride = frame->linesize[0] / 2;
279  old_frame_data = (uint16_t*)s->frame->data[0];
280  old_stride = s->frame->linesize[0] / 2;
281 
282  for (superblock_index = 0; superblock_index < s->num_superblocks;
283  superblock_index++) {
284  MacroBlock mb;
285  SuperBlock sb;
286  unsigned multi_mask = 0;
287 
288  if (skip == -1) {
289  // Note that this call will make us skip the rest of the blocks
290  // if the frame prematurely ends
291  skip = decode_skip_count(&gb);
292  }
293 
294  if (skip) {
295  copy_superblock(new_frame_data, new_stride,
296  old_frame_data, old_stride);
297  } else {
298  copy_superblock(sb.pixels, 8,
299  old_frame_data, old_stride);
300 
301  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
302  unsigned mask;
303  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
304  mask = get_bits(&gb, 16);
305  multi_mask |= mask;
306  for (i = 0; i < 16; i++) {
307  if (mask & mask_matrix[i]) {
308  insert_mb_into_sb(&sb, mb, i);
309  }
310  }
311  }
312 
313  if (!get_bits1(&gb)) {
314  unsigned inv_mask = get_bits(&gb, 4);
315  for (i = 0; i < 4; i++) {
316  if (inv_mask & (1 << i)) {
317  multi_mask ^= 0xF << i*4;
318  } else {
319  multi_mask ^= get_bits(&gb, 4) << i*4;
320  }
321  }
322 
323  for (i = 0; i < 16; i++) {
324  if (multi_mask & mask_matrix[i]) {
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 (get_bits_left(&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 
353  av_log(avctx, AV_LOG_DEBUG,
354  "Escape sizes: %i, %i, %i\n",
355  frame_size, buf_size, get_bits_count(&gb) / 8);
356 
357  av_frame_unref(s->frame);
358  if ((ret = av_frame_ref(s->frame, frame)) < 0)
359  return ret;
360 
361  *got_frame = 1;
362 
363  return frame_size;
364 }
365 
366 
368  .name = "escape124",
369  .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
370  .type = AVMEDIA_TYPE_VIDEO,
371  .id = AV_CODEC_ID_ESCAPE124,
372  .priv_data_size = sizeof(Escape124Context),
374  .close = escape124_decode_close,
376  .capabilities = AV_CODEC_CAP_DR1,
377 };
static const uint16_t mask_matrix[]
Definition: escape124.c:194
const char * s
Definition: avisynth_c.h:631
#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:180
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:260
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int size
Definition: avcodec.h:1578
int av_log2(unsigned v)
Definition: intmath.c:26
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1870
unsigned size
Definition: escape124.c:40
AVCodec.
Definition: avcodec.h:3535
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:172
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:97
#define av_cold
Definition: attributes.h:82
#define av_malloc(s)
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:140
#define mb
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:118
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:374
static void copy_superblock(uint16_t *dest, unsigned dest_stride, uint16_t *src, unsigned src_stride)
Definition: escape124.c:181
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1577
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:212
uint32_t pixels32[2]
Definition: escape124.c:30
bitstream reader API header.
uint16_t pixels[4]
Definition: escape124.c:29
ptrdiff_t size
Definition: opengl_enc.c:101
#define av_log(a,...)
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:607
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:153
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
CodeBook codebooks[3]
Definition: escape124.c:49
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
AVFrame * frame
Definition: escape124.c:45
const char * name
Name of the codec implementation.
Definition: avcodec.h:3542
int depth
Definition: v4l.c:62
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:73
int width
picture width / height.
Definition: avcodec.h:1829
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:109
AVCodec ff_escape124_decoder
Definition: escape124.c:367
#define src
Definition: vp9dsp.c:530
MacroBlock * blocks
Definition: escape124.c:41
uint16_t pixels[64]
Definition: escape124.c:34
int frame_size
Definition: mxfenc.c:1821
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:211
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:449
main external API structure.
Definition: avcodec.h:1642
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:928
unsigned depth
Definition: escape124.c:39
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:312
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:86
int index
Definition: gxfenc.c:89
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:345
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:481
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:194
static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
Definition: ccaption_dec.c:722
common internal api header.
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:326
void * priv_data
Definition: avcodec.h:1684
uint32_t pixels32[32]
Definition: escape124.c:35
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:57
#define av_freep(p)
This structure stores compressed data.
Definition: avcodec.h:1554
#define AV_GET_BUFFER_FLAG_REF
The decoder will keep a reference to the frame and may reuse it later.
Definition: avcodec.h:1338
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:953
static av_always_inline int get_bitsz(GetBitContext *s, int n)
Read 0-25 bits.
Definition: get_bits.h:275
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:140
static int escape124_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:199