FFmpeg  4.2.1
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, MAX_UINT_BITS(width), 0)
45 #define uir(width, name) \
46  xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0)
47 #define uis(width, name, subs, ...) \
48  xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
49 #define uirs(width, name, subs, ...) \
50  xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
51 #define sis(width, name, subs, ...) \
52  xsi(width, name, current->name, subs, __VA_ARGS__)
53 
54 
55 #define READ
56 #define READWRITE read
57 #define RWContext GetBitContext
58 
59 #define xui(width, name, var, range_min, range_max, subs, ...) do { \
60  uint32_t value = 0; \
61  CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
62  SUBSCRIPTS(subs, __VA_ARGS__), \
63  &value, range_min, range_max)); \
64  var = value; \
65  } while (0)
66 
67 #define xsi(width, name, var, subs, ...) do { \
68  int32_t value; \
69  CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
70  SUBSCRIPTS(subs, __VA_ARGS__), &value, \
71  MIN_INT_BITS(width), \
72  MAX_INT_BITS(width))); \
73  var = value; \
74  } while (0)
75 
76 #define marker_bit() do { \
77  av_unused uint32_t one; \
78  CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", NULL, &one, 1, 1)); \
79  } while (0)
80 
81 #define nextbits(width, compare, var) \
82  (get_bits_left(rw) >= width && \
83  (var = show_bits(rw, width)) == (compare))
84 
86 
87 #undef READ
88 #undef READWRITE
89 #undef RWContext
90 #undef xui
91 #undef xsi
92 #undef marker_bit
93 #undef nextbits
94 
95 
96 #define WRITE
97 #define READWRITE write
98 #define RWContext PutBitContext
99 
100 #define xui(width, name, var, range_min, range_max, subs, ...) do { \
101  CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
102  SUBSCRIPTS(subs, __VA_ARGS__), \
103  var, range_min, range_max)); \
104  } while (0)
105 
106 #define xsi(width, name, var, subs, ...) do { \
107  CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
108  SUBSCRIPTS(subs, __VA_ARGS__), var, \
109  MIN_INT_BITS(width), \
110  MAX_INT_BITS(width))); \
111  } while (0)
112 
113 #define marker_bit() do { \
114  CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", NULL, 1, 1, 1)); \
115  } while (0)
116 
117 #define nextbits(width, compare, var) (var)
118 
120 
121 #undef WRITE
122 #undef READWRITE
123 #undef RWContext
124 #undef xui
125 #undef xsi
126 #undef marker_bit
127 #undef nextbits
128 
129 
130 static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
131 {
132  MPEG2RawUserData *user = (MPEG2RawUserData*)content;
134  av_freep(&content);
135 }
136 
137 static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
138 {
139  MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
141  av_buffer_unref(&slice->data_ref);
142  av_freep(&content);
143 }
144 
147  int header)
148 {
149  const uint8_t *start, *end;
150  uint8_t *unit_data;
151  uint32_t start_code = -1, next_start_code = -1;
152  size_t unit_size;
153  int err, i, unit_type;
154 
155  start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
156  &start_code);
157  for (i = 0;; i++) {
158  end = avpriv_find_start_code(start, frag->data + frag->data_size,
159  &next_start_code);
160 
161  unit_type = start_code & 0xff;
162 
163  // The start and end pointers point at to the byte following the
164  // start_code_identifier in the start code that they found.
165  if (end == frag->data + frag->data_size) {
166  // We didn't find a start code, so this is the final unit.
167  unit_size = end - (start - 1);
168  } else {
169  // Unit runs from start to the beginning of the start code
170  // pointed to by end (including any padding zeroes).
171  unit_size = (end - 4) - (start - 1);
172  }
173 
174  unit_data = (uint8_t *)start - 1;
175 
176  err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
177  unit_data, unit_size, frag->data_ref);
178  if (err < 0)
179  return err;
180 
181  if (end == frag->data + frag->data_size)
182  break;
183 
184  start_code = next_start_code;
185  start = end;
186  }
187 
188  return 0;
189 }
190 
192  CodedBitstreamUnit *unit)
193 {
194  GetBitContext gbc;
195  int err;
196 
197  err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
198  if (err < 0)
199  return err;
200 
201  if (MPEG2_START_IS_SLICE(unit->type)) {
202  MPEG2RawSlice *slice;
203  int pos, len;
204 
205  err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
207  if (err < 0)
208  return err;
209  slice = unit->content;
210 
211  err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
212  if (err < 0)
213  return err;
214 
215  pos = get_bits_count(&gbc);
216  len = unit->data_size;
217 
218  slice->data_size = len - pos / 8;
219  slice->data_ref = av_buffer_ref(unit->data_ref);
220  if (!slice->data_ref)
221  return AVERROR(ENOMEM);
222  slice->data = unit->data + pos / 8;
223 
224  slice->data_bit_start = pos % 8;
225 
226  } else {
227  switch (unit->type) {
228 #define START(start_code, type, read_func, free_func) \
229  case start_code: \
230  { \
231  type *header; \
232  err = ff_cbs_alloc_unit_content(ctx, unit, \
233  sizeof(*header), free_func); \
234  if (err < 0) \
235  return err; \
236  header = unit->content; \
237  err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
238  if (err < 0) \
239  return err; \
240  } \
241  break;
252 #undef START
253  default:
254  return AVERROR(ENOSYS);
255  }
256  }
257 
258  return 0;
259 }
260 
262  CodedBitstreamUnit *unit,
263  PutBitContext *pbc)
264 {
265  int err;
266 
267  switch (unit->type) {
268 #define START(start_code, type, func) \
269  case start_code: \
270  err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
271  break;
278 #undef START
279  default:
280  av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
281  "code %02"PRIx32".\n", unit->type);
282  return AVERROR_PATCHWELCOME;
283  }
284 
285  return err;
286 }
287 
289  CodedBitstreamUnit *unit,
290  PutBitContext *pbc)
291 {
292  MPEG2RawSlice *slice = unit->content;
293  int err;
294 
295  err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
296  if (err < 0)
297  return err;
298 
299  if (slice->data) {
300  size_t rest = slice->data_size - (slice->data_bit_start + 7) / 8;
301  uint8_t *pos = slice->data + slice->data_bit_start / 8;
302 
303  av_assert0(slice->data_bit_start >= 0 &&
304  8 * slice->data_size > slice->data_bit_start);
305 
306  if (slice->data_size * 8 + 8 > put_bits_left(pbc))
307  return AVERROR(ENOSPC);
308 
309  // First copy the remaining bits of the first byte
310  if (slice->data_bit_start % 8)
311  put_bits(pbc, 8 - slice->data_bit_start % 8,
312  *pos++ & MAX_UINT_BITS(8 - slice->data_bit_start % 8));
313 
314  if (put_bits_count(pbc) % 8 == 0) {
315  // If the writer is aligned at this point,
316  // memcpy can be used to improve performance.
317  // This is the normal case.
318  flush_put_bits(pbc);
319  memcpy(put_bits_ptr(pbc), pos, rest);
320  skip_put_bytes(pbc, rest);
321  } else {
322  // If not, we have to copy manually:
323  for (; rest > 3; rest -= 4, pos += 4)
324  put_bits32(pbc, AV_RB32(pos));
325 
326  for (; rest; rest--, pos++)
327  put_bits(pbc, 8, *pos);
328 
329  // Align with zeros
330  put_bits(pbc, 8 - put_bits_count(pbc) % 8, 0);
331  }
332  }
333 
334  return 0;
335 }
336 
338  CodedBitstreamUnit *unit)
339 {
341  PutBitContext pbc;
342  int err;
343 
344  if (!priv->write_buffer) {
345  // Initial write buffer size is 1MB.
346  priv->write_buffer_size = 1024 * 1024;
347 
348  reallocate_and_try_again:
349  err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
350  if (err < 0) {
351  av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
352  "sufficiently large write buffer (last attempt "
353  "%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
354  return err;
355  }
356  }
357 
358  init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
359 
360  if (MPEG2_START_IS_SLICE(unit->type))
361  err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
362  else
363  err = cbs_mpeg2_write_header(ctx, unit, &pbc);
364 
365  if (err == AVERROR(ENOSPC)) {
366  // Overflow.
367  priv->write_buffer_size *= 2;
368  goto reallocate_and_try_again;
369  }
370  if (err < 0) {
371  // Write failed for some other reason.
372  return err;
373  }
374 
375  if (put_bits_count(&pbc) % 8)
376  unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
377  else
378  unit->data_bit_padding = 0;
379 
380  unit->data_size = (put_bits_count(&pbc) + 7) / 8;
381  flush_put_bits(&pbc);
382 
383  err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
384  if (err < 0)
385  return err;
386 
387  memcpy(unit->data, priv->write_buffer, unit->data_size);
388 
389  return 0;
390 }
391 
394 {
395  uint8_t *data;
396  size_t size, dp;
397  int i;
398 
399  size = 0;
400  for (i = 0; i < frag->nb_units; i++)
401  size += 3 + frag->units[i].data_size;
402 
404  if (!frag->data_ref)
405  return AVERROR(ENOMEM);
406  data = frag->data_ref->data;
407 
408  dp = 0;
409  for (i = 0; i < frag->nb_units; i++) {
410  CodedBitstreamUnit *unit = &frag->units[i];
411 
412  data[dp++] = 0;
413  data[dp++] = 0;
414  data[dp++] = 1;
415 
416  memcpy(data + dp, unit->data, unit->data_size);
417  dp += unit->data_size;
418  }
419 
420  av_assert0(dp == size);
421 
422  memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
423  frag->data = data;
424  frag->data_size = size;
425 
426  return 0;
427 }
428 
430 {
432 
433  av_freep(&priv->write_buffer);
434 }
435 
438 
439  .priv_data_size = sizeof(CodedBitstreamMPEG2Context),
440 
441  .split_fragment = &cbs_mpeg2_split_fragment,
442  .read_unit = &cbs_mpeg2_read_unit,
443  .write_unit = &cbs_mpeg2_write_unit,
444  .assemble_fragment = &cbs_mpeg2_assemble_fragment,
445 
446  .close = &cbs_mpeg2_close,
447 };
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
Write exactly 32 bits into a bitstream.
Definition: put_bits.h:250
#define NULL
Definition: coverity.c:32
int nb_units
Number of units in this fragment.
Definition: cbs.h:147
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
int size
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
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:588
static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Definition: cbs_mpeg2.c:337
static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
Definition: cbs_mpeg2.c:130
static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Definition: cbs_mpeg2.c:191
#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:392
static int FUNC() extension_data(CodedBitstreamContext *ctx, RWContext *rw, H265RawPSExtensionData *current)
uint8_t
#define MAX_UINT_BITS(length)
Definition: cbs_internal.h:96
#define AV_RB32
Definition: intreadwrite.h:130
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
const char data[16]
Definition: mxf.c:91
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
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:609
Coded bitstream unit structure.
Definition: cbs.h:64
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_allocated.
Definition: cbs.h:162
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:703
#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
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static uint8_t * put_bits_ptr(PutBitContext *s)
Return the pointer to the byte where the bitstream writer will put the next bit.
Definition: put_bits.h:324
static int put_bits_left(PutBitContext *s)
Definition: put_bits.h:93
#define AVERROR(e)
Definition: error.h:43
const char const char AVS_ApplyFunc void * user_data
Definition: avisynth_c.h:867
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:145
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:173
static void skip_put_bytes(PutBitContext *s, int n)
Skip the given number of bytes.
Definition: put_bits.h:333
#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:436
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:168
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
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:288
MPEG2RawSliceHeader header
Definition: cbs_mpeg2.h:205
void * priv_data
Internal codec-specific data.
Definition: cbs.h:189
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:429
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:790
int len
static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
Definition: cbs_mpeg2.c:137
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:766
static const uint8_t start_code[]
static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, PutBitContext *pbc)
Definition: cbs_mpeg2.c:261
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