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 "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 
85 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
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  // Check if the amount we will read minimally is available on input.
225  // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
226  // represent a lower bound of the space needed for skipped superblocks. Non
227  // skipped SBs need more space.
228  if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)
229  return -1;
230 
231  frame_flags = get_bits_long(&gb, 32);
232  frame_size = get_bits_long(&gb, 32);
233 
234  // Leave last frame unchanged
235  // FIXME: Is this necessary? I haven't seen it in any real samples
236  if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
237  if (!s->frame->data[0])
238  return AVERROR_INVALIDDATA;
239 
240  av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
241 
242  *got_frame = 1;
243  if ((ret = av_frame_ref(frame, s->frame)) < 0)
244  return ret;
245 
246  return frame_size;
247  }
248 
249  for (i = 0; i < 3; i++) {
250  if (frame_flags & (1 << (17 + i))) {
251  unsigned cb_depth, cb_size;
252  if (i == 2) {
253  // This codebook can be cut off at places other than
254  // powers of 2, leaving some of the entries undefined.
255  cb_size = get_bits(&gb, 20);
256  if (!cb_size) {
257  av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
258  return AVERROR_INVALIDDATA;
259  }
260  cb_depth = av_log2(cb_size - 1) + 1;
261  } else {
262  cb_depth = get_bits(&gb, 4);
263  if (i == 0) {
264  // This is the most basic codebook: pow(2,depth) entries
265  // for a depth-length key
266  cb_size = 1 << cb_depth;
267  } else {
268  // This codebook varies per superblock
269  // FIXME: I don't think this handles integer overflow
270  // properly
271  cb_size = s->num_superblocks << cb_depth;
272  }
273  }
274  if (s->num_superblocks >= INT_MAX >> cb_depth) {
275  av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n");
276  return AVERROR_INVALIDDATA;
277  }
278 
279  av_freep(&s->codebooks[i].blocks);
280  s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
281  if (!s->codebooks[i].blocks)
282  return -1;
283  }
284  }
285 
286  if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
287  return ret;
288 
289  new_frame_data = (uint16_t*)frame->data[0];
290  new_stride = frame->linesize[0] / 2;
291  old_frame_data = (uint16_t*)s->frame->data[0];
292  old_stride = s->frame->linesize[0] / 2;
293 
294  for (superblock_index = 0; superblock_index < s->num_superblocks;
295  superblock_index++) {
296  MacroBlock mb;
297  SuperBlock sb;
298  unsigned multi_mask = 0;
299 
300  if (skip == -1) {
301  // Note that this call will make us skip the rest of the blocks
302  // if the frame prematurely ends
303  skip = decode_skip_count(&gb);
304  }
305 
306  if (skip) {
307  copy_superblock(new_frame_data, new_stride,
308  old_frame_data, old_stride);
309  } else {
310  copy_superblock(sb.pixels, 8,
311  old_frame_data, old_stride);
312 
313  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
314  unsigned mask;
315  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
316  mask = get_bits(&gb, 16);
317  multi_mask |= mask;
318  for (i = 0; i < 16; i++) {
319  if (mask & mask_matrix[i]) {
320  insert_mb_into_sb(&sb, mb, i);
321  }
322  }
323  }
324 
325  if (!get_bits1(&gb)) {
326  unsigned inv_mask = get_bits(&gb, 4);
327  for (i = 0; i < 4; i++) {
328  if (inv_mask & (1 << i)) {
329  multi_mask ^= 0xF << i*4;
330  } else {
331  multi_mask ^= get_bits(&gb, 4) << i*4;
332  }
333  }
334 
335  for (i = 0; i < 16; i++) {
336  if (multi_mask & mask_matrix[i]) {
337  mb = decode_macroblock(s, &gb, &cb_index,
338  superblock_index);
339  insert_mb_into_sb(&sb, mb, i);
340  }
341  }
342  } else if (frame_flags & (1 << 16)) {
343  while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
344  mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
345  insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
346  }
347  }
348 
349  copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
350  }
351 
352  superblock_col_index++;
353  new_frame_data += 8;
354  if (old_frame_data)
355  old_frame_data += 8;
356  if (superblock_col_index == superblocks_per_row) {
357  new_frame_data += new_stride * 8 - superblocks_per_row * 8;
358  if (old_frame_data)
359  old_frame_data += old_stride * 8 - superblocks_per_row * 8;
360  superblock_col_index = 0;
361  }
362  skip--;
363  }
364 
365  av_log(avctx, AV_LOG_DEBUG,
366  "Escape sizes: %i, %i, %i\n",
367  frame_size, buf_size, get_bits_count(&gb) / 8);
368 
369  av_frame_unref(s->frame);
370  if ((ret = av_frame_ref(s->frame, frame)) < 0)
371  return ret;
372 
373  *got_frame = 1;
374 
375  return frame_size;
376 }
377 
378 
380  .name = "escape124",
381  .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
382  .type = AVMEDIA_TYPE_VIDEO,
383  .id = AV_CODEC_ID_ESCAPE124,
384  .priv_data_size = sizeof(Escape124Context),
386  .close = escape124_decode_close,
388  .capabilities = AV_CODEC_CAP_DR1,
389  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
390 };
AVCodec
AVCodec.
Definition: codec.h:197
FF_CODEC_CAP_INIT_THREADSAFE
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
init
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
insert_mb_into_sb
static void insert_mb_into_sb(SuperBlock *sb, MacroBlock mb, unsigned index)
Definition: escape124.c:171
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:850
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:193
cb
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:215
get_bits_long
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:547
MacroBlock::pixels32
uint32_t pixels32[2]
Definition: escape124.c:29
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:220
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:111
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
index
fg index
Definition: ffmpeg_filter.c:168
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:365
MacroBlock
Definition: escape124.c:27
data
const char data[16]
Definition: mxf.c:142
SuperBlock::pixels
uint16_t pixels[64]
Definition: escape124.c:33
decode_macroblock
static MacroBlock decode_macroblock(Escape124Context *s, GetBitContext *gb, int *codebook_index, int superblock_index)
Definition: escape124.c:139
Escape124Context
Definition: escape124.c:43
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:380
SuperBlock::pixels32
uint32_t pixels32[32]
Definition: escape124.c:34
GetBitContext
Definition: get_bits.h:62
av_frame_alloc
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:98
ff_escape124_decoder
const AVCodec ff_escape124_decoder
Definition: escape124.c:379
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
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:678
mask
static const uint16_t mask[17]
Definition: lzw.c:38
decode
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
MacroBlock::pixels
uint16_t pixels[4]
Definition: escape124.c:28
s
#define s(width, name)
Definition: cbs_vp9.c:257
Escape124Context::codebooks
CodeBook codebooks[3]
Definition: escape124.c:48
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:362
frame_size
int frame_size
Definition: mxfenc.c:2206
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:202
get_bits.h
escape124_decode_frame
static int escape124_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: escape124.c:198
Escape124Context::frame
AVFrame * frame
Definition: escape124.c:44
CodeBook::size
unsigned size
Definition: escape124.c:39
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:499
src
#define src
Definition: vp8dsp.c:255
copy_superblock
static void copy_superblock(uint16_t *dest, unsigned dest_stride, uint16_t *src, unsigned src_stride)
Definition: escape124.c:180
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1645
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:366
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
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:326
size
int size
Definition: twinvq_data.h:10344
mb
#define mb
Definition: vf_colormatrix.c:101
i
int i
Definition: input.c:407
unpack_codebook
static CodeBook unpack_codebook(GetBitContext *gb, unsigned depth, unsigned size)
Definition: escape124.c:85
escape124_decode_close
static av_cold int escape124_decode_close(AVCodecContext *avctx)
Definition: escape124.c:72
SuperBlock
Definition: escape124.c:32
AV_PIX_FMT_RGB555
#define AV_PIX_FMT_RGB555
Definition: pixfmt.h:377
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
av_frame_unref
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:436
CodeBook::depth
unsigned depth
Definition: escape124.c:38
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:204
AVCodecContext::height
int height
Definition: avcodec.h:557
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:594
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:165
AVCodecContext
main external API structure.
Definition: avcodec.h:384
CodeBook::blocks
MacroBlock * blocks
Definition: escape124.c:40
escape124_decode_init
static av_cold int escape124_decode_init(AVCodecContext *avctx)
Initialize the decoder.
Definition: escape124.c:56
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:416
CodeBook
Definition: escape124.c:37
AVPacket
This structure stores compressed data.
Definition: packet.h:342
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:411
decode_skip_count
static unsigned decode_skip_count(GetBitContext *gb)
Definition: escape124.c:117
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:557
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
Escape124Context::num_superblocks
unsigned num_superblocks
Definition: escape124.c:46
av_log2
int av_log2(unsigned v)
Definition: intmath.c:26