FFmpeg
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 #define BITSTREAM_READER_LE
23 #include "avcodec.h"
24 #include "codec_internal.h"
25 #include "decode.h"
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 
86 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
87  unsigned size)
88 {
89  unsigned i, j;
90  CodeBook cb = { 0 };
91 
92  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
93  if (!cb.blocks)
94  return cb;
95 
96  cb.depth = depth;
97  cb.size = size;
98  for (i = 0; i < size; i++) {
99  unsigned mask_bits = get_bits(gb, 4);
100  unsigned color[2];
101  color[0] = get_bits(gb, 15);
102  color[1] = get_bits(gb, 15);
103 
104  for (j = 0; j < 4; j++)
105  cb.blocks[i].pixels[j] = color[(mask_bits>>j) & 1];
106  }
107  return cb;
108 }
109 
110 static unsigned decode_skip_count(GetBitContext* gb)
111 {
112  unsigned value;
113  // This function reads a maximum of 23 bits,
114  // which is within the padding space
115  if (get_bits_left(gb) < 1)
116  return -1;
117  value = get_bits1(gb);
118  if (!value)
119  return value;
120 
121  value += get_bits(gb, 3);
122  if (value != (1 + ((1 << 3) - 1)))
123  return value;
124 
125  value += get_bits(gb, 7);
126  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
127  return value;
128 
129  return value + get_bits(gb, 12);
130 }
131 
133  int* codebook_index, int superblock_index)
134 {
135  // This function reads a maximum of 22 bits; the callers
136  // guard this function appropriately
137  unsigned block_index, depth;
138  int value = get_bits1(gb);
139  if (value) {
140  static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
141  value = get_bits1(gb);
142  *codebook_index = transitions[*codebook_index][value];
143  }
144 
145  depth = s->codebooks[*codebook_index].depth;
146 
147  // depth = 0 means that this shouldn't read any bits;
148  // in theory, this is the same as get_bits(gb, 0), but
149  // that doesn't actually work.
150  block_index = get_bitsz(gb, depth);
151 
152  if (*codebook_index == 1) {
153  block_index += superblock_index << s->codebooks[1].depth;
154  }
155 
156  // This condition can occur with invalid bitstreams and
157  // *codebook_index == 2
158  if (block_index >= s->codebooks[*codebook_index].size || !s->codebooks[*codebook_index].blocks)
159  return (MacroBlock) { { 0 } };
160 
161  return s->codebooks[*codebook_index].blocks[block_index];
162 }
163 
164 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
165  // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
166  uint32_t *dst = sb->pixels32 + index + (index & -4);
167 
168  // This technically violates C99 aliasing rules, but it should be safe.
169  dst[0] = mb.pixels32[0];
170  dst[4] = mb.pixels32[1];
171 }
172 
173 static void copy_superblock(uint16_t* dest, ptrdiff_t dest_stride,
174  uint16_t* src, ptrdiff_t src_stride)
175 {
176  unsigned y;
177  if (src)
178  for (y = 0; y < 8; y++)
179  memcpy(dest + y * dest_stride, src + y * src_stride,
180  sizeof(uint16_t) * 8);
181  else
182  for (y = 0; y < 8; y++)
183  memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
184 }
185 
186 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
187  0x4, 0x8, 0x40, 0x80,
188  0x100, 0x200, 0x1000, 0x2000,
189  0x400, 0x800, 0x4000, 0x8000};
190 
192  int *got_frame, AVPacket *avpkt)
193 {
194  int buf_size = avpkt->size;
195  Escape124Context *s = avctx->priv_data;
196 
197  GetBitContext gb;
198  unsigned frame_flags, frame_size;
199  unsigned i;
200 
201  unsigned superblock_index, cb_index = 1,
202  superblock_col_index = 0,
203  superblocks_per_row = avctx->width / 8, skip = -1;
204 
205  uint16_t* old_frame_data, *new_frame_data;
206  ptrdiff_t old_stride, new_stride;
207 
208  int ret;
209 
210  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
211  return ret;
212 
213  // This call also guards the potential depth reads for the
214  // codebook unpacking.
215  // Check if the amount we will read minimally is available on input.
216  // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
217  // represent a lower bound of the space needed for skipped superblocks. Non
218  // skipped SBs need more space.
219  if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)
220  return AVERROR_INVALIDDATA;
221 
222  frame_flags = get_bits_long(&gb, 32);
223  frame_size = get_bits_long(&gb, 32);
224 
225  // Leave last frame unchanged
226  // FIXME: Is this necessary? I haven't seen it in any real samples
227  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
228  if (!s->frame->data[0])
229  return AVERROR_INVALIDDATA;
230 
231  av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
232 
233  *got_frame = 1;
234  if ((ret = av_frame_ref(frame, s->frame)) < 0)
235  return ret;
236 
237  return 0;
238  }
239 
240  for (i = 0; i < 3; i++) {
241  if (frame_flags & (1 << (17 + i))) {
242  unsigned cb_depth, cb_size;
243  if (i == 2) {
244  // This codebook can be cut off at places other than
245  // powers of 2, leaving some of the entries undefined.
246  cb_size = get_bits(&gb, 20);
247  if (!cb_size) {
248  av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
249  return AVERROR_INVALIDDATA;
250  }
251  cb_depth = av_log2(cb_size - 1) + 1;
252  } else {
253  cb_depth = get_bits(&gb, 4);
254  if (i == 0) {
255  // This is the most basic codebook: pow(2,depth) entries
256  // for a depth-length key
257  cb_size = 1 << cb_depth;
258  } else {
259  // This codebook varies per superblock
260  // FIXME: I don't think this handles integer overflow
261  // properly
262  cb_size = s->num_superblocks << cb_depth;
263  }
264  }
265  if (s->num_superblocks >= INT_MAX >> cb_depth) {
266  av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n");
267  return AVERROR_INVALIDDATA;
268  }
269 
270  av_freep(&s->codebooks[i].blocks);
271  if (cb_size >= INT_MAX / 34 || get_bits_left(&gb) < (int)cb_size * 34)
272  return AVERROR_INVALIDDATA;
273 
274  if (cb_size >= INT_MAX / sizeof(MacroBlock))
275  return AVERROR_INVALIDDATA;
276  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
277  if (!s->codebooks[i].blocks)
278  return AVERROR(ENOMEM);
279  }
280  }
281 
282  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
283  return ret;
284 
285  new_frame_data = (uint16_t*)frame->data[0];
286  new_stride = frame->linesize[0] / 2;
287  old_frame_data = (uint16_t*)s->frame->data[0];
288  old_stride = s->frame->linesize[0] / 2;
289 
290  for (superblock_index = 0; superblock_index < s->num_superblocks;
291  superblock_index++) {
292  MacroBlock mb;
293  SuperBlock sb;
294  unsigned multi_mask = 0;
295 
296  if (skip == -1) {
297  // Note that this call will make us skip the rest of the blocks
298  // if the frame prematurely ends
299  skip = decode_skip_count(&gb);
300  }
301 
302  if (skip) {
303  copy_superblock(new_frame_data, new_stride,
304  old_frame_data, old_stride);
305  } else {
306  copy_superblock(sb.pixels, 8,
307  old_frame_data, old_stride);
308 
309  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
310  unsigned mask;
311  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
312  mask = get_bits(&gb, 16);
313  multi_mask |= mask;
314  for (i = 0; i < 16; i++) {
315  if (mask & mask_matrix[i]) {
316  insert_mb_into_sb(&sb, mb, i);
317  }
318  }
319  }
320 
321  if (!get_bits1(&gb)) {
322  unsigned inv_mask = get_bits(&gb, 4);
323  for (i = 0; i < 4; i++) {
324  if (inv_mask & (1 << i)) {
325  multi_mask ^= 0xF << i*4;
326  } else {
327  multi_mask ^= get_bits(&gb, 4) << i*4;
328  }
329  }
330 
331  for (i = 0; i < 16; i++) {
332  if (multi_mask & mask_matrix[i]) {
333  mb = decode_macroblock(s, &gb, &cb_index,
334  superblock_index);
335  insert_mb_into_sb(&sb, mb, i);
336  }
337  }
338  } else if (frame_flags & (1 << 16)) {
339  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
340  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
341  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
342  }
343  }
344 
345  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
346  }
347 
348  superblock_col_index++;
349  new_frame_data += 8;
350  if (old_frame_data)
351  old_frame_data += 8;
352  if (superblock_col_index == superblocks_per_row) {
353  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
354  if (old_frame_data)
355  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
356  superblock_col_index = 0;
357  }
358  skip--;
359  }
360 
361  av_log(avctx, AV_LOG_DEBUG,
362  "Escape sizes: %i, %i, %i\n",
363  frame_size, buf_size, get_bits_count(&gb) / 8);
364 
365  if ((ret = av_frame_replace(s->frame, frame)) < 0)
366  return ret;
367 
368  *got_frame = 1;
369 
370  return 0;
371 }
372 
373 
375  .p.name = "escape124",
376  CODEC_LONG_NAME("Escape 124"),
377  .p.type = AVMEDIA_TYPE_VIDEO,
378  .p.id = AV_CODEC_ID_ESCAPE124,
379  .priv_data_size = sizeof(Escape124Context),
381  .close = escape124_decode_close,
383  .p.capabilities = AV_CODEC_CAP_DR1,
384 };
copy_superblock
static void copy_superblock(uint16_t *dest, ptrdiff_t dest_stride, uint16_t *src, ptrdiff_t src_stride)
Definition: escape124.c:173
insert_mb_into_sb
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:164
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:694
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
mask_matrix
static const uint16_t mask_matrix[]
Definition: escape124.c:186
color
Definition: vf_paletteuse.c:511
cb
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:241
get_bits_long
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:421
MacroBlock::pixels32
uint32_t pixels32[2]
Definition: escape124.c:30
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:266
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:100
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
AVPacket::data
uint8_t * data
Definition: packet.h:522
MacroBlock
Definition: escape124.c:28
FFCodec
Definition: codec_internal.h:127
SuperBlock::pixels
uint16_t pixels[64]
Definition: escape124.c:34
decode_macroblock
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:132
Escape124Context
Definition: escape124.c:44
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:361
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:30
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:335
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
SuperBlock::pixels32
uint32_t pixels32[32]
Definition: escape124.c:35
GetBitContext
Definition: get_bits.h:108
av_frame_alloc
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:88
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
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:545
mask
static const uint16_t mask[17]
Definition: lzw.c:38
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:306
MacroBlock::pixels
uint16_t pixels[4]
Definition: escape124.c:29
s
#define s(width, name)
Definition: cbs_vp9.c:198
Escape124Context::codebooks
CodeBook codebooks[3]
Definition: escape124.c:49
AV_GET_BUFFER_FLAG_REF
#define AV_GET_BUFFER_FLAG_REF
The decoder will keep a reference to the frame and may reuse it later.
Definition: avcodec.h:425
frame_size
int frame_size
Definition: mxfenc.c:2422
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:201
decode.h
get_bits.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
frame
static AVFrame * frame
Definition: demux_decode.c:54
Escape124Context::frame
AVFrame * frame
Definition: escape124.c:45
escape124_decode_frame
static int escape124_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:191
CodeBook::size
unsigned size
Definition: escape124.c:40
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:388
index
int index
Definition: gxfenc.c:89
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1618
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:365
ff_escape124_decoder
const FFCodec ff_escape124_decoder
Definition: escape124.c:374
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:523
av_frame_ref
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:361
codec_internal.h
size
int size
Definition: twinvq_data.h:10344
mb
#define mb
Definition: vf_colormatrix.c:99
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
unpack_codebook
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:86
escape124_decode_close
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:73
SuperBlock
Definition: escape124.c:33
AV_PIX_FMT_RGB555
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:470
value
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 default value
Definition: writing_filters.txt:86
CodeBook::depth
unsigned depth
Definition: escape124.c:39
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
AVCodecContext::height
int height
Definition: avcodec.h:625
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:662
avcodec.h
ret
ret
Definition: filter_design.txt:187
AV_CODEC_ID_ESCAPE124
@ AV_CODEC_ID_ESCAPE124
Definition: codec_id.h:167
av_frame_replace
int av_frame_replace(AVFrame *dst, const AVFrame *src)
Ensure the destination frame refers to the same data described by the source frame,...
Definition: frame.c:482
AVCodecContext
main external API structure.
Definition: avcodec.h:445
CodeBook::blocks
MacroBlock * blocks
Definition: escape124.c:41
escape124_decode_init
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:57
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
get_bitsz
static av_always_inline int get_bitsz(GetBitContext *s, int n)
Read 0-25 bits.
Definition: get_bits.h:351
CodeBook
Definition: escape124.c:38
AVPacket
This structure stores compressed data.
Definition: packet.h:499
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
decode_skip_count
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:110
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
src
INIT_CLIP pixel * src
Definition: h264pred_template.c:418
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:625
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, a positive or negative value, which is typically indicating the size in bytes of each pict...
Definition: frame.h:385
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
Escape124Context::num_superblocks
unsigned num_superblocks
Definition: escape124.c:47
av_log2
int av_log2(unsigned v)
Definition: intmath.c:26
skip
static void BS_FUNC() skip(BSCTX *bc, unsigned int n)
Skip n bits in the buffer.
Definition: bitstream_template.h:375