FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
cbs_mpeg2.c
Go to the documentation of this file.
1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include "libavutil/avassert.h"
20 
21 #include "cbs.h"
22 #include "cbs_internal.h"
23 #include "cbs_mpeg2.h"
24 #include "internal.h"
25 
26 
27 #define HEADER(name) do { \
28  ff_cbs_trace_header(ctx, name); \
29  } while (0)
30 
31 #define CHECK(call) do { \
32  err = (call); \
33  if (err < 0) \
34  return err; \
35  } while (0)
36 
37 #define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
38 #define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
39 #define FUNC(name) FUNC_MPEG2(READWRITE, name)
40 
41 #define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
42 
43 #define ui(width, name) \
44  xui(width, name, current->name, 0)
45 #define uis(width, name, subs, ...) \
46  xui(width, name, current->name, subs, __VA_ARGS__)
47 
48 
49 #define READ
50 #define READWRITE read
51 #define RWContext GetBitContext
52 
53 #define xui(width, name, var, subs, ...) do { \
54  uint32_t value = 0; \
55  CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
56  SUBSCRIPTS(subs, __VA_ARGS__), \
57  &value, 0, (1 << width) - 1)); \
58  var = value; \
59  } while (0)
60 
61 #define marker_bit() do { \
62  av_unused uint32_t one; \
63  CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", NULL, &one, 1, 1)); \
64  } while (0)
65 
66 #define nextbits(width, compare, var) \
67  (get_bits_left(rw) >= width && \
68  (var = show_bits(rw, width)) == (compare))
69 
71 
72 #undef READ
73 #undef READWRITE
74 #undef RWContext
75 #undef xui
76 #undef marker_bit
77 #undef nextbits
78 
79 
80 #define WRITE
81 #define READWRITE write
82 #define RWContext PutBitContext
83 
84 #define xui(width, name, var, subs, ...) do { \
85  CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
86  SUBSCRIPTS(subs, __VA_ARGS__), \
87  var, 0, (1 << width) - 1)); \
88  } while (0)
89 
90 #define marker_bit() do { \
91  CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", NULL, 1, 1, 1)); \
92  } while (0)
93 
94 #define nextbits(width, compare, var) (var)
95 
97 
98 #undef READ
99 #undef READWRITE
100 #undef RWContext
101 #undef xui
102 #undef marker_bit
103 #undef nextbits
104 
105 
106 static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
107 {
108  MPEG2RawUserData *user = (MPEG2RawUserData*)content;
110  av_freep(&content);
111 }
112 
113 static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
114 {
115  MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
117  av_buffer_unref(&slice->data_ref);
118  av_freep(&content);
119 }
120 
123  int header)
124 {
125  const uint8_t *start, *end;
126  uint8_t *unit_data;
127  uint32_t start_code = -1, next_start_code = -1;
128  size_t unit_size;
129  int err, i, unit_type;
130 
131  start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
132  &start_code);
133  for (i = 0;; i++) {
134  end = avpriv_find_start_code(start, frag->data + frag->data_size,
135  &next_start_code);
136 
137  unit_type = start_code & 0xff;
138 
139  // The start and end pointers point at to the byte following the
140  // start_code_identifier in the start code that they found.
141  if (end == frag->data + frag->data_size) {
142  // We didn't find a start code, so this is the final unit.
143  unit_size = end - (start - 1);
144  } else {
145  // Unit runs from start to the beginning of the start code
146  // pointed to by end (including any padding zeroes).
147  unit_size = (end - 4) - (start - 1);
148  }
149 
150  unit_data = (uint8_t *)start - 1;
151 
152  err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
153  unit_data, unit_size, frag->data_ref);
154  if (err < 0)
155  return err;
156 
157  if (end == frag->data + frag->data_size)
158  break;
159 
160  start_code = next_start_code;
161  start = end;
162  }
163 
164  return 0;
165 }
166 
168  CodedBitstreamUnit *unit)
169 {
170  GetBitContext gbc;
171  int err;
172 
173  err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
174  if (err < 0)
175  return err;
176 
177  if (MPEG2_START_IS_SLICE(unit->type)) {
178  MPEG2RawSlice *slice;
179  int pos, len;
180 
181  err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
183  if (err < 0)
184  return err;
185  slice = unit->content;
186 
187  err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
188  if (err < 0)
189  return err;
190 
191  pos = get_bits_count(&gbc);
192  len = unit->data_size;
193 
194  slice->data_size = len - pos / 8;
195  slice->data_ref = av_buffer_ref(unit->data_ref);
196  if (!slice->data_ref)
197  return AVERROR(ENOMEM);
198  slice->data = unit->data + pos / 8;
199 
200  slice->data_bit_start = pos % 8;
201 
202  } else {
203  switch (unit->type) {
204 #define START(start_code, type, read_func, free_func) \
205  case start_code: \
206  { \
207  type *header; \
208  err = ff_cbs_alloc_unit_content(ctx, unit, \
209  sizeof(*header), free_func); \
210  if (err < 0) \
211  return err; \
212  header = unit->content; \
213  err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
214  if (err < 0) \
215  return err; \
216  } \
217  break;
225 #undef START
226  default:
227  av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02"PRIx32".\n",
228  unit->type);
229  return AVERROR_INVALIDDATA;
230  }
231  }
232 
233  return 0;
234 }
235 
237  CodedBitstreamUnit *unit,
238  PutBitContext *pbc)
239 {
240  int err;
241 
242  switch (unit->type) {
243 #define START(start_code, type, func) \
244  case start_code: \
245  err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
246  break;
252 #undef START
253  default:
254  av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
255  "code %02"PRIx32".\n", unit->type);
256  return AVERROR_PATCHWELCOME;
257  }
258 
259  return err;
260 }
261 
263  CodedBitstreamUnit *unit,
264  PutBitContext *pbc)
265 {
266  MPEG2RawSlice *slice = unit->content;
267  GetBitContext gbc;
268  size_t bits_left;
269  int err;
270 
271  err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
272  if (err < 0)
273  return err;
274 
275  if (slice->data) {
276  if (slice->data_size * 8 + 8 > put_bits_left(pbc))
277  return AVERROR(ENOSPC);
278 
279  init_get_bits(&gbc, slice->data, slice->data_size * 8);
280  skip_bits_long(&gbc, slice->data_bit_start);
281 
282  while (get_bits_left(&gbc) > 15)
283  put_bits(pbc, 16, get_bits(&gbc, 16));
284 
285  bits_left = get_bits_left(&gbc);
286  put_bits(pbc, bits_left, get_bits(&gbc, bits_left));
287 
288  // Align with zeroes.
289  while (put_bits_count(pbc) % 8 != 0)
290  put_bits(pbc, 1, 0);
291  }
292 
293  return 0;
294 }
295 
297  CodedBitstreamUnit *unit)
298 {
300  PutBitContext pbc;
301  int err;
302 
303  if (!priv->write_buffer) {
304  // Initial write buffer size is 1MB.
305  priv->write_buffer_size = 1024 * 1024;
306 
307  reallocate_and_try_again:
308  err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
309  if (err < 0) {
310  av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
311  "sufficiently large write buffer (last attempt "
312  "%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
313  return err;
314  }
315  }
316 
317  init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
318 
319  if (unit->type >= 0x01 && unit->type <= 0xaf)
320  err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
321  else
322  err = cbs_mpeg2_write_header(ctx, unit, &pbc);
323 
324  if (err == AVERROR(ENOSPC)) {
325  // Overflow.
326  priv->write_buffer_size *= 2;
327  goto reallocate_and_try_again;
328  }
329  if (err < 0) {
330  // Write failed for some other reason.
331  return err;
332  }
333 
334  if (put_bits_count(&pbc) % 8)
335  unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
336  else
337  unit->data_bit_padding = 0;
338 
339  unit->data_size = (put_bits_count(&pbc) + 7) / 8;
340  flush_put_bits(&pbc);
341 
342  err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
343  if (err < 0)
344  return err;
345 
346  memcpy(unit->data, priv->write_buffer, unit->data_size);
347 
348  return 0;
349 }
350 
353 {
354  uint8_t *data;
355  size_t size, dp;
356  int i;
357 
358  size = 0;
359  for (i = 0; i < frag->nb_units; i++)
360  size += 3 + frag->units[i].data_size;
361 
363  if (!frag->data_ref)
364  return AVERROR(ENOMEM);
365  data = frag->data_ref->data;
366 
367  dp = 0;
368  for (i = 0; i < frag->nb_units; i++) {
369  CodedBitstreamUnit *unit = &frag->units[i];
370 
371  data[dp++] = 0;
372  data[dp++] = 0;
373  data[dp++] = 1;
374 
375  memcpy(data + dp, unit->data, unit->data_size);
376  dp += unit->data_size;
377  }
378 
379  av_assert0(dp == size);
380 
381  memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
382  frag->data = data;
383  frag->data_size = size;
384 
385  return 0;
386 }
387 
389 {
391 
392  av_freep(&priv->write_buffer);
393 }
394 
397 
398  .priv_data_size = sizeof(CodedBitstreamMPEG2Context),
399 
400  .split_fragment = &cbs_mpeg2_split_fragment,
401  .read_unit = &cbs_mpeg2_read_unit,
402  .write_unit = &cbs_mpeg2_write_unit,
403  .assemble_fragment = &cbs_mpeg2_assemble_fragment,
404 
405  .close = &cbs_mpeg2_close,
406 };
#define NULL
Definition: coverity.c:32
int nb_units
Number of units in this fragment.
Definition: cbs.h:147
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
void av_buffer_unref(AVBufferRef **buf)
Free a given reference and automatically free the buffer if there are no more references to it...
Definition: buffer.c:125
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
uint8_t * data
Definition: cbs_mpeg2.h:207
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:208
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:269
static void skip_bits_long(GetBitContext *s, int n)
Skips the specified number of bits.
Definition: get_bits.h:212
CodedBitstreamUnitType type
Codec-specific type of this unit.
Definition: cbs.h:68
int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, size_t size, void(*free)(void *opaque, uint8_t *data))
Definition: cbs.c:494
static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Definition: cbs_mpeg2.c:296
static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
Definition: cbs_mpeg2.c:106
static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Definition: cbs_mpeg2.c:167
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag)
Definition: cbs_mpeg2.c:351
static int FUNC() extension_data(CodedBitstreamContext *ctx, RWContext *rw, H265RawPSExtensionData *current)
uint8_t
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
AVBufferRef * extra_information_ref
Definition: cbs_mpeg2.h:201
size_t data_bit_padding
The number of bits which should be ignored in the final byte.
Definition: cbs.h:86
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:200
int ff_cbs_alloc_unit_data(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, size_t size)
Allocate a new internal data buffer of the given size in the unit.
Definition: cbs.c:515
Coded bitstream unit structure.
Definition: cbs.h:64
ptrdiff_t size
Definition: opengl_enc.c:101
void * content
Pointer to the decomposed form of this unit.
Definition: cbs.h:101
static const uint8_t header[24]
Definition: sdr2.c:67
CodedBitstreamUnit * units
Pointer to an array of units of length nb_units.
Definition: cbs.h:153
uint8_t * data
Pointer to the directly-parsable bitstream form of this unit.
Definition: cbs.h:75
int ff_cbs_insert_unit_data(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, int position, CodedBitstreamUnitType type, uint8_t *data, size_t data_size, AVBufferRef *data_buf)
Insert a new unit into a fragment with the given data bitstream.
Definition: cbs.c:595
#define av_log(a,...)
const uint8_t * avpriv_find_start_code(const uint8_t *p, const uint8_t *end, uint32_t *state)
size_t data_size
The number of bytes in the bitstream.
Definition: cbs.h:129
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:596
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static int put_bits_left(PutBitContext *s)
Definition: put_bits.h:93
#define AVERROR(e)
Definition: error.h:43
AVS_Value void * user_data
Definition: avisynth_c.h:699
AVBufferRef * user_data_ref
Definition: cbs_mpeg2.h:81
simple assert() macros that are a bit more flexible than ISO C assert().
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:85
static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, int header)
Definition: cbs_mpeg2.c:121
static int FUNC() picture_header(CodedBitstreamContext *ctx, RWContext *rw, MPEG2RawPictureHeader *current)
void * log_ctx
Logging context to be passed to all av_log() calls associated with this context.
Definition: cbs.h:164
#define START(start_code, type, read_func, free_func)
AVFormatContext * ctx
Definition: movenc.c:48
preferred ID for MPEG-1/2 video decoding
Definition: avcodec.h:220
uint8_t * data
Pointer to the bitstream form of this fragment.
Definition: cbs.h:122
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
const CodedBitstreamType ff_cbs_type_mpeg2
Definition: cbs_mpeg2.c:395
int av_reallocp(void *ptr, size_t size)
Allocate, reallocate, or free a block of memory through a pointer to a pointer.
Definition: mem.c:163
int data_bit_start
Definition: cbs_mpeg2.h:209
static int FUNC() sequence_header(CodedBitstreamContext *ctx, RWContext *rw, MPEG2RawSequenceHeader *current)
AVBufferRef * av_buffer_alloc(int size)
Allocate an AVBuffer of the given size using av_malloc().
Definition: buffer.c:67
Coded bitstream fragment structure, combining one or more units.
Definition: cbs.h:116
#define MPEG2_START_IS_SLICE(type)
Definition: cbs_mpeg2.h:40
uint8_t * data
The data buffer.
Definition: buffer.h:89
Context structure for coded bitstream operations.
Definition: cbs.h:159
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:433
enum AVCodecID codec_id
Definition: cbs_internal.h:29
#define SIZE_SPECIFIER
Definition: internal.h:262
static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, PutBitContext *pbc)
Definition: cbs_mpeg2.c:262
MPEG2RawSliceHeader header
Definition: cbs_mpeg2.h:205
void * priv_data
Internal codec-specific data.
Definition: cbs.h:180
common internal api header.
static void flush_put_bits(PutBitContext *s)
Pad the end of the output stream with zeros.
Definition: put_bits.h:101
static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
Definition: cbs_mpeg2.c:388
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:92
AVBufferRef * av_buffer_ref(AVBufferRef *buf)
Create a new reference to an AVBuffer.
Definition: buffer.c:93
static int FUNC() group_of_pictures_header(CodedBitstreamContext *ctx, RWContext *rw, MPEG2RawGroupOfPicturesHeader *current)
static void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Initialize the PutBitContext s.
Definition: put_bits.h:48
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:777
int len
static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
Definition: cbs_mpeg2.c:113
AVBufferRef * data_ref
Definition: cbs_mpeg2.h:210
size_t data_size
Definition: cbs_mpeg2.h:208
#define av_freep(p)
void INT64 start
Definition: avisynth_c.h:690
static const uint8_t start_code[]
static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, PutBitContext *pbc)
Definition: cbs_mpeg2.c:236
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:139
size_t data_size
The number of bytes in the bitstream (including any padding bits in the final byte).
Definition: cbs.h:80