FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
escape124.c
Go to the documentation of this file.
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 #define BITSTREAM_READER_LE
23 #include "avcodec.h"
24 #include "get_bits.h"
25 #include "internal.h"
26 
27 typedef union MacroBlock {
28  uint16_t pixels[4];
29  uint32_t pixels32[2];
30 } MacroBlock;
31 
32 typedef union SuperBlock {
33  uint16_t pixels[64];
34  uint32_t pixels32[32];
35 } SuperBlock;
36 
37 typedef struct CodeBook {
38  unsigned depth;
39  unsigned size;
41 } CodeBook;
42 
43 typedef struct Escape124Context {
45 
46  unsigned num_superblocks;
47 
50 
51 /**
52  * Initialize the decoder
53  * @param avctx decoder context
54  * @return 0 success, negative on error
55  */
57 {
58  Escape124Context *s = avctx->priv_data;
59 
60  avctx->pix_fmt = AV_PIX_FMT_RGB555;
61 
62  s->num_superblocks = ((unsigned)avctx->width / 8) *
63  ((unsigned)avctx->height / 8);
64 
65  s->frame = av_frame_alloc();
66  if (!s->frame)
67  return AVERROR(ENOMEM);
68 
69  return 0;
70 }
71 
73 {
74  unsigned i;
75  Escape124Context *s = avctx->priv_data;
76 
77  for (i = 0; i < 3; i++)
78  av_freep(&s->codebooks[i].blocks);
79 
80  av_frame_free(&s->frame);
81 
82  return 0;
83 }
84 
86  unsigned size)
87 {
88  unsigned i, j;
89  CodeBook cb = { 0 };
90 
91  if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
92  return cb;
93 
94  if (size >= INT_MAX / sizeof(MacroBlock))
95  return cb;
96  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
97  if (!cb.blocks)
98  return cb;
99 
100  cb.depth = depth;
101  cb.size = size;
102  for (i = 0; i < size; i++) {
103  unsigned mask_bits = get_bits(gb, 4);
104  unsigned color0 = get_bits(gb, 15);
105  unsigned color1 = get_bits(gb, 15);
106 
107  for (j = 0; j < 4; j++) {
108  if (mask_bits & (1 << j))
109  cb.blocks[i].pixels[j] = color1;
110  else
111  cb.blocks[i].pixels[j] = color0;
112  }
113  }
114  return cb;
115 }
116 
117 static unsigned decode_skip_count(GetBitContext* gb)
118 {
119  unsigned value;
120  // This function reads a maximum of 23 bits,
121  // which is within the padding space
122  if (get_bits_left(gb) < 1)
123  return -1;
124  value = get_bits1(gb);
125  if (!value)
126  return value;
127 
128  value += get_bits(gb, 3);
129  if (value != (1 + ((1 << 3) - 1)))
130  return value;
131 
132  value += get_bits(gb, 7);
133  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
134  return value;
135 
136  return value + get_bits(gb, 12);
137 }
138 
140  int* codebook_index, int superblock_index)
141 {
142  // This function reads a maximum of 22 bits; the callers
143  // guard this function appropriately
144  unsigned block_index, depth;
145  int value = get_bits1(gb);
146  if (value) {
147  static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
148  value = get_bits1(gb);
149  *codebook_index = transitions[*codebook_index][value];
150  }
151 
152  depth = s->codebooks[*codebook_index].depth;
153 
154  // depth = 0 means that this shouldn't read any bits;
155  // in theory, this is the same as get_bits(gb, 0), but
156  // that doesn't actually work.
157  block_index = get_bitsz(gb, depth);
158 
159  if (*codebook_index == 1) {
160  block_index += superblock_index << s->codebooks[1].depth;
161  }
162 
163  // This condition can occur with invalid bitstreams and
164  // *codebook_index == 2
165  if (block_index >= s->codebooks[*codebook_index].size)
166  return (MacroBlock) { { 0 } };
167 
168  return s->codebooks[*codebook_index].blocks[block_index];
169 }
170 
171 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
172  // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
173  uint32_t *dst = sb->pixels32 + index + (index & -4);
174 
175  // This technically violates C99 aliasing rules, but it should be safe.
176  dst[0] = mb.pixels32[0];
177  dst[4] = mb.pixels32[1];
178 }
179 
180 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
181  uint16_t* src, unsigned src_stride)
182 {
183  unsigned y;
184  if (src)
185  for (y = 0; y < 8; y++)
186  memcpy(dest + y * dest_stride, src + y * src_stride,
187  sizeof(uint16_t) * 8);
188  else
189  for (y = 0; y < 8; y++)
190  memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
191 }
192 
193 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
194  0x4, 0x8, 0x40, 0x80,
195  0x100, 0x200, 0x1000, 0x2000,
196  0x400, 0x800, 0x4000, 0x8000};
197 
199  void *data, int *got_frame,
200  AVPacket *avpkt)
201 {
202  int buf_size = avpkt->size;
203  Escape124Context *s = avctx->priv_data;
204  AVFrame *frame = data;
205 
206  GetBitContext gb;
207  unsigned frame_flags, frame_size;
208  unsigned i;
209 
210  unsigned superblock_index, cb_index = 1,
211  superblock_col_index = 0,
212  superblocks_per_row = avctx->width / 8, skip = -1;
213 
214  uint16_t* old_frame_data, *new_frame_data;
215  unsigned old_stride, new_stride;
216 
217  int ret;
218 
219  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
220  return ret;
221 
222  // This call also guards the potential depth reads for the
223  // codebook unpacking.
224  if (get_bits_left(&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  if (!s->frame->data[0])
234  return AVERROR_INVALIDDATA;
235 
236  av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
237 
238  *got_frame = 1;
239  if ((ret = av_frame_ref(frame, s->frame)) < 0)
240  return ret;
241 
242  return frame_size;
243  }
244 
245  for (i = 0; i < 3; i++) {
246  if (frame_flags & (1 << (17 + i))) {
247  unsigned cb_depth, cb_size;
248  if (i == 2) {
249  // This codebook can be cut off at places other than
250  // powers of 2, leaving some of the entries undefined.
251  cb_size = get_bits_long(&gb, 20);
252  if (!cb_size) {
253  av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
254  return AVERROR_INVALIDDATA;
255  }
256  cb_depth = av_log2(cb_size - 1) + 1;
257  } else {
258  cb_depth = get_bits(&gb, 4);
259  if (i == 0) {
260  // This is the most basic codebook: pow(2,depth) entries
261  // for a depth-length key
262  cb_size = 1 << cb_depth;
263  } else {
264  // This codebook varies per superblock
265  // FIXME: I don't think this handles integer overflow
266  // properly
267  cb_size = s->num_superblocks << cb_depth;
268  }
269  }
270  av_freep(&s->codebooks[i].blocks);
271  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
272  if (!s->codebooks[i].blocks)
273  return -1;
274  }
275  }
276 
277  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
278  return ret;
279 
280  new_frame_data = (uint16_t*)frame->data[0];
281  new_stride = frame->linesize[0] / 2;
282  old_frame_data = (uint16_t*)s->frame->data[0];
283  old_stride = s->frame->linesize[0] / 2;
284 
285  for (superblock_index = 0; superblock_index < s->num_superblocks;
286  superblock_index++) {
287  MacroBlock mb;
288  SuperBlock sb;
289  unsigned multi_mask = 0;
290 
291  if (skip == -1) {
292  // Note that this call will make us skip the rest of the blocks
293  // if the frame prematurely ends
294  skip = decode_skip_count(&gb);
295  }
296 
297  if (skip) {
298  copy_superblock(new_frame_data, new_stride,
299  old_frame_data, old_stride);
300  } else {
301  copy_superblock(sb.pixels, 8,
302  old_frame_data, old_stride);
303 
304  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
305  unsigned mask;
306  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
307  mask = get_bits(&gb, 16);
308  multi_mask |= mask;
309  for (i = 0; i < 16; i++) {
310  if (mask & mask_matrix[i]) {
311  insert_mb_into_sb(&sb, mb, i);
312  }
313  }
314  }
315 
316  if (!get_bits1(&gb)) {
317  unsigned inv_mask = get_bits(&gb, 4);
318  for (i = 0; i < 4; i++) {
319  if (inv_mask & (1 << i)) {
320  multi_mask ^= 0xF << i*4;
321  } else {
322  multi_mask ^= get_bits(&gb, 4) << i*4;
323  }
324  }
325 
326  for (i = 0; i < 16; i++) {
327  if (multi_mask & mask_matrix[i]) {
328  mb = decode_macroblock(s, &gb, &cb_index,
329  superblock_index);
330  insert_mb_into_sb(&sb, mb, i);
331  }
332  }
333  } else if (frame_flags & (1 << 16)) {
334  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
335  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
336  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
337  }
338  }
339 
340  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
341  }
342 
343  superblock_col_index++;
344  new_frame_data += 8;
345  if (old_frame_data)
346  old_frame_data += 8;
347  if (superblock_col_index == superblocks_per_row) {
348  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
349  if (old_frame_data)
350  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
351  superblock_col_index = 0;
352  }
353  skip--;
354  }
355 
356  av_log(avctx, AV_LOG_DEBUG,
357  "Escape sizes: %i, %i, %i\n",
358  frame_size, buf_size, get_bits_count(&gb) / 8);
359 
360  av_frame_unref(s->frame);
361  if ((ret = av_frame_ref(s->frame, frame)) < 0)
362  return ret;
363 
364  *got_frame = 1;
365 
366  return frame_size;
367 }
368 
369 
371  .name = "escape124",
372  .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
373  .type = AVMEDIA_TYPE_VIDEO,
374  .id = AV_CODEC_ID_ESCAPE124,
375  .priv_data_size = sizeof(Escape124Context),
377  .close = escape124_decode_close,
379  .capabilities = AV_CODEC_CAP_DR1,
380 };
static const uint16_t mask_matrix[]
Definition: escape124.c:193
const char * s
Definition: avisynth_c.h:768
#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:190
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:247
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int size
Definition: avcodec.h:1608
int av_log2(unsigned v)
Definition: intmath.c:26
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1910
unsigned size
Definition: escape124.c:39
#define src
Definition: vp8dsp.c:254
AVCodec.
Definition: avcodec.h:3607
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:171
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:145
#define mb
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:117
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:385
static void copy_superblock(uint16_t *dest, unsigned dest_stride, uint16_t *src, unsigned src_stride)
Definition: escape124.c:180
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1607
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:199
uint32_t pixels32[2]
Definition: escape124.c:29
bitstream reader API header.
uint16_t pixels[4]
Definition: escape124.c:28
ptrdiff_t size
Definition: opengl_enc.c:101
#define av_log(a,...)
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:572
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
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:158
#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:48
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
AVFrame * frame
Definition: escape124.c:44
const char * name
Name of the codec implementation.
Definition: avcodec.h:3614
int depth
Definition: v4l.c:62
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:72
int width
picture width / height.
Definition: avcodec.h:1869
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:109
AVCodec ff_escape124_decoder
Definition: escape124.c:370
MacroBlock * blocks
Definition: escape124.c:40
uint16_t pixels[64]
Definition: escape124.c:33
int frame_size
Definition: mxfenc.c:1820
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:221
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:441
main external API structure.
Definition: avcodec.h:1682
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:948
unsigned depth
Definition: escape124.c:38
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:299
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:85
int index
Definition: gxfenc.c:89
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:332
unsigned num_superblocks
Definition: escape124.c:46
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:495
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:204
common internal api header.
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:339
void * priv_data
Definition: avcodec.h:1724
uint32_t pixels32[32]
Definition: escape124.c:34
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:56
#define av_freep(p)
static int decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
Definition: ffmpeg.c:2045
This structure stores compressed data.
Definition: avcodec.h:1584
#define AV_GET_BUFFER_FLAG_REF
The decoder will keep a reference to the frame and may reuse it later.
Definition: avcodec.h:1354
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:959
static av_always_inline int get_bitsz(GetBitContext *s, int n)
Read 0-25 bits.
Definition: get_bits.h:262
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:139
static int escape124_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:198