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 "libavutil/mem.h"
24 #include "avcodec.h"
25 #include "codec_internal.h"
26 #include "decode.h"
27 #include "get_bits.h"
28 
29 typedef union MacroBlock {
30  uint16_t pixels[4];
31  uint32_t pixels32[2];
32 } MacroBlock;
33 
34 typedef union SuperBlock {
35  uint16_t pixels[64];
36  uint32_t pixels32[32];
37 } SuperBlock;
38 
39 typedef struct CodeBook {
40  unsigned depth;
41  unsigned size;
43 } CodeBook;
44 
45 typedef struct Escape124Context {
47 
48  unsigned num_superblocks;
49 
52 
53 /**
54  * Initialize the decoder
55  * @param avctx decoder context
56  * @return 0 success, negative on error
57  */
59 {
60  Escape124Context *s = avctx->priv_data;
61 
62  avctx->pix_fmt = AV_PIX_FMT_RGB555;
63 
64  s->num_superblocks = ((unsigned)avctx->width / 8) *
65  ((unsigned)avctx->height / 8);
66 
67  s->frame = av_frame_alloc();
68  if (!s->frame)
69  return AVERROR(ENOMEM);
70 
71  return 0;
72 }
73 
75 {
76  unsigned i;
77  Escape124Context *s = avctx->priv_data;
78 
79  for (i = 0; i < 3; i++)
80  av_freep(&s->codebooks[i].blocks);
81 
82  av_frame_free(&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  cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
94  if (!cb.blocks)
95  return cb;
96 
97  cb.depth = depth;
98  cb.size = size;
99  for (i = 0; i < size; i++) {
100  unsigned mask_bits = get_bits(gb, 4);
101  unsigned color[2];
102  color[0] = get_bits(gb, 15);
103  color[1] = get_bits(gb, 15);
104 
105  for (j = 0; j < 4; j++)
106  cb.blocks[i].pixels[j] = color[(mask_bits>>j) & 1];
107  }
108  return cb;
109 }
110 
111 static unsigned decode_skip_count(GetBitContext* gb)
112 {
113  unsigned value;
114  // This function reads a maximum of 23 bits,
115  // which is within the padding space
116  if (get_bits_left(gb) < 1)
117  return -1;
118  value = get_bits1(gb);
119  if (!value)
120  return value;
121 
122  value += get_bits(gb, 3);
123  if (value != (1 + ((1 << 3) - 1)))
124  return value;
125 
126  value += get_bits(gb, 7);
127  if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
128  return value;
129 
130  return value + get_bits(gb, 12);
131 }
132 
134  int* codebook_index, int superblock_index)
135 {
136  // This function reads a maximum of 22 bits; the callers
137  // guard this function appropriately
138  unsigned block_index, depth;
139  int value = get_bits1(gb);
140  if (value) {
141  static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
142  value = get_bits1(gb);
143  *codebook_index = transitions[*codebook_index][value];
144  }
145 
146  depth = s->codebooks[*codebook_index].depth;
147 
148  // depth = 0 means that this shouldn't read any bits;
149  // in theory, this is the same as get_bits(gb, 0), but
150  // that doesn't actually work.
151  block_index = get_bitsz(gb, depth);
152 
153  if (*codebook_index == 1) {
154  block_index += superblock_index << s->codebooks[1].depth;
155  }
156 
157  // This condition can occur with invalid bitstreams and
158  // *codebook_index == 2
159  if (block_index >= s->codebooks[*codebook_index].size || !s->codebooks[*codebook_index].blocks)
160  return (MacroBlock) { { 0 } };
161 
162  return s->codebooks[*codebook_index].blocks[block_index];
163 }
164 
165 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
166  // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
167  uint32_t *dst = sb->pixels32 + index + (index & -4);
168 
169  // This technically violates C99 aliasing rules, but it should be safe.
170  dst[0] = mb.pixels32[0];
171  dst[4] = mb.pixels32[1];
172 }
173 
174 static void copy_superblock(uint16_t* dest, ptrdiff_t dest_stride,
175  uint16_t* src, ptrdiff_t src_stride)
176 {
177  unsigned y;
178  if (src)
179  for (y = 0; y < 8; y++)
180  memcpy(dest + y * dest_stride, src + y * src_stride,
181  sizeof(uint16_t) * 8);
182  else
183  for (y = 0; y < 8; y++)
184  memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
185 }
186 
187 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
188  0x4, 0x8, 0x40, 0x80,
189  0x100, 0x200, 0x1000, 0x2000,
190  0x400, 0x800, 0x4000, 0x8000};
191 
193  int *got_frame, AVPacket *avpkt)
194 {
195  int buf_size = avpkt->size;
196  Escape124Context *s = avctx->priv_data;
197 
198  GetBitContext gb;
199  unsigned frame_flags, frame_size;
200  unsigned i;
201 
202  unsigned superblock_index, cb_index = 1,
203  superblock_col_index = 0,
204  superblocks_per_row = avctx->width / 8, skip = -1;
205 
206  uint16_t* old_frame_data, *new_frame_data;
207  ptrdiff_t old_stride, new_stride;
208 
209  int ret;
210 
211  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
212  return ret;
213 
214  // This call also guards the potential depth reads for the
215  // codebook unpacking.
216  // Check if the amount we will read minimally is available on input.
217  // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
218  // represent a lower bound of the space needed for skipped superblocks. Non
219  // skipped SBs need more space.
220  if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)
221  return AVERROR_INVALIDDATA;
222 
223  frame_flags = get_bits_long(&gb, 32);
224  frame_size = get_bits_long(&gb, 32);
225 
226  // Leave last frame unchanged
227  // FIXME: Is this necessary? I haven't seen it in any real samples
228  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
229  if (!s->frame->data[0])
230  return AVERROR_INVALIDDATA;
231 
232  av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
233 
234  *got_frame = 1;
235  if ((ret = av_frame_ref(frame, s->frame)) < 0)
236  return ret;
237 
238  return 0;
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(&gb, 20);
248  if (!cb_size) {
249  av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
250  return AVERROR_INVALIDDATA;
251  }
252  cb_depth = av_log2(cb_size - 1) + 1;
253  } else {
254  cb_depth = get_bits(&gb, 4);
255  if (i == 0) {
256  // This is the most basic codebook: pow(2,depth) entries
257  // for a depth-length key
258  cb_size = 1 << cb_depth;
259  } else {
260  // This codebook varies per superblock
261  // FIXME: I don't think this handles integer overflow
262  // properly
263  cb_size = s->num_superblocks << cb_depth;
264  }
265  }
266  if (s->num_superblocks >= INT_MAX >> cb_depth) {
267  av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n");
268  return AVERROR_INVALIDDATA;
269  }
270 
271  av_freep(&s->codebooks[i].blocks);
272  if (cb_size >= INT_MAX / 34 || get_bits_left(&gb) < (int)cb_size * 34)
273  return AVERROR_INVALIDDATA;
274 
275  if (cb_size >= INT_MAX / sizeof(MacroBlock))
276  return AVERROR_INVALIDDATA;
277  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
278  if (!s->codebooks[i].blocks)
279  return AVERROR(ENOMEM);
280  }
281  }
282 
283  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
284  return ret;
285 
286  new_frame_data = (uint16_t*)frame->data[0];
287  new_stride = frame->linesize[0] / 2;
288  old_frame_data = (uint16_t*)s->frame->data[0];
289  old_stride = s->frame->linesize[0] / 2;
290 
291  for (superblock_index = 0; superblock_index < s->num_superblocks;
292  superblock_index++) {
293  MacroBlock mb;
294  SuperBlock sb;
295  unsigned multi_mask = 0;
296 
297  if (skip == -1) {
298  // Note that this call will make us skip the rest of the blocks
299  // if the frame prematurely ends
300  skip = decode_skip_count(&gb);
301  }
302 
303  if (skip) {
304  copy_superblock(new_frame_data, new_stride,
305  old_frame_data, old_stride);
306  } else {
307  copy_superblock(sb.pixels, 8,
308  old_frame_data, old_stride);
309 
310  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
311  unsigned mask;
312  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
313  mask = get_bits(&gb, 16);
314  multi_mask |= mask;
315  for (i = 0; i < 16; i++) {
316  if (mask & mask_matrix[i]) {
317  insert_mb_into_sb(&sb, mb, i);
318  }
319  }
320  }
321 
322  if (!get_bits1(&gb)) {
323  unsigned inv_mask = get_bits(&gb, 4);
324  for (i = 0; i < 4; i++) {
325  if (inv_mask & (1 << i)) {
326  multi_mask ^= 0xF << i*4;
327  } else {
328  multi_mask ^= get_bits(&gb, 4) << i*4;
329  }
330  }
331 
332  for (i = 0; i < 16; i++) {
333  if (multi_mask & mask_matrix[i]) {
334  mb = decode_macroblock(s, &gb, &cb_index,
335  superblock_index);
336  insert_mb_into_sb(&sb, mb, i);
337  }
338  }
339  } else if (frame_flags & (1 << 16)) {
340  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
341  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
342  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
343  }
344  }
345 
346  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
347  }
348 
349  superblock_col_index++;
350  new_frame_data += 8;
351  if (old_frame_data)
352  old_frame_data += 8;
353  if (superblock_col_index == superblocks_per_row) {
354  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
355  if (old_frame_data)
356  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
357  superblock_col_index = 0;
358  }
359  skip--;
360  }
361 
362  av_log(avctx, AV_LOG_DEBUG,
363  "Escape sizes: %i, %i, %i\n",
364  frame_size, buf_size, get_bits_count(&gb) / 8);
365 
366  if ((ret = av_frame_replace(s->frame, frame)) < 0)
367  return ret;
368 
369  *got_frame = 1;
370 
371  return 0;
372 }
373 
374 
376  .p.name = "escape124",
377  CODEC_LONG_NAME("Escape 124"),
378  .p.type = AVMEDIA_TYPE_VIDEO,
379  .p.id = AV_CODEC_ID_ESCAPE124,
380  .priv_data_size = sizeof(Escape124Context),
382  .close = escape124_decode_close,
384  .p.capabilities = AV_CODEC_CAP_DR1,
385 };
copy_superblock
static void copy_superblock(uint16_t *dest, ptrdiff_t dest_stride, uint16_t *src, ptrdiff_t src_stride)
Definition: escape124.c:174
insert_mb_into_sb
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:165
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:695
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:187
color
Definition: vf_paletteuse.c:512
cb
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:246
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:31
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:160
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:374
AVPacket::data
uint8_t * data
Definition: packet.h:520
MacroBlock
Definition: escape124.c:29
FFCodec
Definition: codec_internal.h:126
SuperBlock::pixels
uint16_t pixels[64]
Definition: escape124.c:35
decode_macroblock
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:133
Escape124Context
Definition: escape124.c:45
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:130
SuperBlock::pixels32
uint32_t pixels32[32]
Definition: escape124.c:36
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:148
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:286
MacroBlock::pixels
uint16_t pixels[4]
Definition: escape124.c:30
s
#define s(width, name)
Definition: cbs_vp9.c:198
Escape124Context::codebooks
CodeBook codebooks[3]
Definition: escape124.c:50
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:2424
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:271
Escape124Context::frame
AVFrame * frame
Definition: escape124.c:46
escape124_decode_frame
static int escape124_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:192
CodeBook::size
unsigned size
Definition: escape124.c:41
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:388
index
int index
Definition: gxfenc.c:90
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1575
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:366
ff_escape124_decoder
const FFCodec ff_escape124_decoder
Definition: escape124.c:375
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:521
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:384
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:256
unpack_codebook
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:87
escape124_decode_close
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:74
SuperBlock
Definition: escape124.c:34
AV_PIX_FMT_RGB555
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:466
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:40
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
AVCodecContext::height
int height
Definition: avcodec.h:618
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:657
avcodec.h
ret
ret
Definition: filter_design.txt:187
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
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:483
AVCodecContext
main external API structure.
Definition: avcodec.h:445
CodeBook::blocks
MacroBlock * blocks
Definition: escape124.c:42
escape124_decode_init
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:58
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
mem.h
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:39
AVPacket
This structure stores compressed data.
Definition: packet.h:497
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
decode_skip_count
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:111
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:618
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:48
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