FFmpeg
cbs.h
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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
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8  *
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11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
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15  * License along with FFmpeg; if not, write to the Free Software
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17  */
18 
19 #ifndef AVCODEC_CBS_H
20 #define AVCODEC_CBS_H
21 
22 #include <stddef.h>
23 #include <stdint.h>
24 
25 #include "libavutil/buffer.h"
26 
27 #include "avcodec.h"
28 
29 
30 /*
31  * This defines a framework for converting between a coded bitstream
32  * and structures defining all individual syntax elements found in
33  * such a stream.
34  *
35  * Conversion in both directions is possible. Given a coded bitstream
36  * (any meaningful fragment), it can be parsed and decomposed into
37  * syntax elements stored in a set of codec-specific structures.
38  * Similarly, given a set of those same codec-specific structures the
39  * syntax elements can be serialised and combined to create a coded
40  * bitstream.
41  */
42 
44 
45 /**
46  * The codec-specific type of a bitstream unit.
47  *
48  * AV1: obu_type
49  * H.264 / AVC: nal_unit_type
50  * H.265 / HEVC: nal_unit_type
51  * JPEG: marker value (without 0xff prefix)
52  * MPEG-2: start code value (without prefix)
53  * VP9: unused, set to zero (every unit is a frame)
54  */
55 typedef uint32_t CodedBitstreamUnitType;
56 
57 /**
58  * Coded bitstream unit structure.
59  *
60  * A bitstream unit the smallest element of a bitstream which
61  * is meaningful on its own. For example, an H.264 NAL unit.
62  *
63  * See the codec-specific header for the meaning of this for any
64  * particular codec.
65  */
66 typedef struct CodedBitstreamUnit {
67  /**
68  * Codec-specific type of this unit.
69  */
71 
72  /**
73  * Pointer to the directly-parsable bitstream form of this unit.
74  *
75  * May be NULL if the unit currently only exists in decomposed form.
76  */
78  /**
79  * The number of bytes in the bitstream (including any padding bits
80  * in the final byte).
81  */
82  size_t data_size;
83  /**
84  * The number of bits which should be ignored in the final byte.
85  *
86  * This supports non-byte-aligned bitstreams.
87  */
89  /**
90  * A reference to the buffer containing data.
91  *
92  * Must be set if data is not NULL.
93  */
95 
96  /**
97  * Pointer to the decomposed form of this unit.
98  *
99  * The type of this structure depends on both the codec and the
100  * type of this unit. May be NULL if the unit only exists in
101  * bitstream form.
102  */
103  void *content;
104  /**
105  * If content is reference counted, a reference to the buffer containing
106  * content. Null if content is not reference counted.
107  */
110 
111 /**
112  * Coded bitstream fragment structure, combining one or more units.
113  *
114  * This is any sequence of units. It need not form some greater whole,
115  * though in many cases it will. For example, an H.264 access unit,
116  * which is composed of a sequence of H.264 NAL units.
117  */
118 typedef struct CodedBitstreamFragment {
119  /**
120  * Pointer to the bitstream form of this fragment.
121  *
122  * May be NULL if the fragment only exists as component units.
123  */
125  /**
126  * The number of bytes in the bitstream.
127  *
128  * The number of bytes in the bitstream (including any padding bits
129  * in the final byte).
130  */
131  size_t data_size;
132  /**
133  * The number of bits which should be ignored in the final byte.
134  */
136  /**
137  * A reference to the buffer containing data.
138  *
139  * Must be set if data is not NULL.
140  */
142 
143  /**
144  * Number of units in this fragment.
145  *
146  * This may be zero if the fragment only exists in bitstream form
147  * and has not been decomposed.
148  */
149  int nb_units;
150 
151  /**
152  * Number of allocated units.
153  *
154  * Must always be >= nb_units; designed for internal use by cbs.
155  */
157 
158  /**
159  * Pointer to an array of units of length nb_units_allocated.
160  * Only the first nb_units are valid.
161  *
162  * Must be NULL if nb_units_allocated is zero.
163  */
166 
167 /**
168  * Context structure for coded bitstream operations.
169  */
170 typedef struct CodedBitstreamContext {
171  /**
172  * Logging context to be passed to all av_log() calls associated
173  * with this context.
174  */
175  void *log_ctx;
176 
177  /**
178  * Internal codec-specific hooks.
179  */
180  const struct CodedBitstreamType *codec;
181 
182  /**
183  * Internal codec-specific data.
184  *
185  * This contains any information needed when reading/writing
186  * bitsteams which will not necessarily be present in a fragment.
187  * For example, for H.264 it contains all currently visible
188  * parameter sets - they are required to determine the bitstream
189  * syntax but need not be present in every access unit.
190  */
191  void *priv_data;
192 
193  /**
194  * Array of unit types which should be decomposed when reading.
195  *
196  * Types not in this list will be available in bitstream form only.
197  * If NULL, all supported types will be decomposed.
198  */
200  /**
201  * Length of the decompose_unit_types array.
202  */
204 
205  /**
206  * Enable trace output during read/write operations.
207  */
209  /**
210  * Log level to use for trace output.
211  *
212  * From AV_LOG_*; defaults to AV_LOG_TRACE.
213  */
215 
216  /**
217  * Write buffer. Used as intermediate buffer when writing units.
218  * For internal use of cbs only.
219  */
223 
224 
225 /**
226  * Table of all supported codec IDs.
227  *
228  * Terminated by AV_CODEC_ID_NONE.
229  */
230 extern const enum AVCodecID ff_cbs_all_codec_ids[];
231 
232 
233 /**
234  * Create and initialise a new context for the given codec.
235  */
237  enum AVCodecID codec_id, void *log_ctx);
238 
239 /**
240  * Reset all internal state in a context.
241  */
243 
244 /**
245  * Close a context and free all internal state.
246  */
248 
249 
250 /**
251  * Read the extradata bitstream found in codec parameters into a
252  * fragment, then split into units and decompose.
253  *
254  * This also updates the internal state, so will need to be called for
255  * codecs with extradata to read parameter sets necessary for further
256  * parsing even if the fragment itself is not desired.
257  *
258  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
259  * before use.
260  */
263  const AVCodecParameters *par);
264 
265 /**
266  * Read the data bitstream from a packet into a fragment, then
267  * split into units and decompose.
268  *
269  * This also updates the internal state of the coded bitstream context
270  * with any persistent data from the fragment which may be required to
271  * read following fragments (e.g. parameter sets).
272  *
273  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
274  * before use.
275  */
278  const AVPacket *pkt);
279 
280 /**
281  * Read a bitstream from a memory region into a fragment, then
282  * split into units and decompose.
283  *
284  * This also updates the internal state of the coded bitstream context
285  * with any persistent data from the fragment which may be required to
286  * read following fragments (e.g. parameter sets).
287  *
288  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
289  * before use.
290  */
293  const uint8_t *data, size_t size);
294 
295 
296 /**
297  * Write the content of the fragment to its own internal buffer.
298  *
299  * Writes the content of all units and then assembles them into a new
300  * data buffer. When modifying the content of decomposed units, this
301  * can be used to regenerate the bitstream form of units or the whole
302  * fragment so that it can be extracted for other use.
303  *
304  * This also updates the internal state of the coded bitstream context
305  * with any persistent data from the fragment which may be required to
306  * write following fragments (e.g. parameter sets).
307  */
309  CodedBitstreamFragment *frag);
310 
311 /**
312  * Write the bitstream of a fragment to the extradata in codec parameters.
313  *
314  * Modifies context and fragment as ff_cbs_write_fragment_data does and
315  * replaces any existing extradata in the structure.
316  */
318  AVCodecParameters *par,
319  CodedBitstreamFragment *frag);
320 
321 /**
322  * Write the bitstream of a fragment to a packet.
323  *
324  * Modifies context and fragment as ff_cbs_write_fragment_data does.
325  *
326  * On success, the packet's buf is unreferenced and its buf, data and
327  * size fields are set to the corresponding values from the newly updated
328  * fragment; other fields are not touched. On failure, the packet is not
329  * touched at all.
330  */
332  AVPacket *pkt,
333  CodedBitstreamFragment *frag);
334 
335 
336 /**
337  * Free the units contained in a fragment as well as the fragment's
338  * own data buffer, but not the units array itself.
339  */
341 
342 /**
343  * Free the units array of a fragment in addition to what
344  * ff_cbs_fragment_reset does.
345  */
347 
348 /**
349  * Allocate a new internal content buffer of the given size in the unit.
350  *
351  * The content will be zeroed.
352  */
354  size_t size,
355  void (*free)(void *opaque, uint8_t *content));
356 
357 /**
358  * Allocate a new internal content buffer matching the type of the unit.
359  *
360  * The content will be zeroed.
361  */
363  CodedBitstreamUnit *unit);
364 
365 
366 /**
367  * Allocate a new internal data buffer of the given size in the unit.
368  *
369  * The data buffer will have input padding.
370  */
372  size_t size);
373 
374 /**
375  * Insert a new unit into a fragment with the given content.
376  *
377  * The content structure continues to be owned by the caller if
378  * content_buf is not supplied.
379  */
381  int position,
383  void *content,
384  AVBufferRef *content_buf);
385 
386 /**
387  * Insert a new unit into a fragment with the given data bitstream.
388  *
389  * If data_buf is not supplied then data must have been allocated with
390  * av_malloc() and will on success become owned by the unit after this
391  * call or freed on error.
392  */
394  int position,
396  uint8_t *data, size_t data_size,
397  AVBufferRef *data_buf);
398 
399 /**
400  * Delete a unit from a fragment and free all memory it uses.
401  *
402  * Requires position to be >= 0 and < frag->nb_units.
403  */
405  int position);
406 
407 
408 /**
409  * Make the content of a unit refcounted.
410  *
411  * If the unit is not refcounted, this will do a deep copy of the unit
412  * content to new refcounted buffers.
413  *
414  * It is not valid to call this function on a unit which does not have
415  * decomposed content.
416  */
418  CodedBitstreamUnit *unit);
419 
420 /**
421  * Make the content of a unit writable so that internal fields can be
422  * modified.
423  *
424  * If it is known that there are no other references to the content of
425  * the unit, does nothing and returns success. Otherwise (including the
426  * case where the unit content is not refcounted), it does a full clone
427  * of the content (including any internal buffers) to make a new copy,
428  * and replaces the existing references inside the unit with that.
429  *
430  * It is not valid to call this function on a unit which does not have
431  * decomposed content.
432  */
434  CodedBitstreamUnit *unit);
435 
436 
437 #endif /* AVCODEC_CBS_H */
int ff_cbs_write_fragment_data(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag)
Write the content of the fragment to its own internal buffer.
Definition: cbs.c:342
int nb_units
Number of units in this fragment.
Definition: cbs.h:149
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
CodedBitstreamUnitType type
Codec-specific type of this unit.
Definition: cbs.h:70
void ff_cbs_fragment_reset(CodedBitstreamFragment *frag)
Free the units contained in a fragment as well as the fragment&#39;s own data buffer, but not the units a...
Definition: cbs.c:147
void ff_cbs_delete_unit(CodedBitstreamFragment *frag, int position)
Delete a unit from a fragment and free all memory it uses.
Definition: cbs.c:796
GLint GLenum type
Definition: opengl_enc.c:104
int ff_cbs_read_extradata(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, const AVCodecParameters *par)
Read the extradata bitstream found in codec parameters into a fragment, then split into units and dec...
Definition: cbs.c:226
static AVPacket pkt
int ff_cbs_alloc_unit_data(CodedBitstreamUnit *unit, size_t size)
Allocate a new internal data buffer of the given size in the unit.
Definition: cbs.c:666
This struct describes the properties of an encoded stream.
Definition: codec_par.h:52
int trace_enable
Enable trace output during read/write operations.
Definition: cbs.h:208
uint8_t
uint32_t CodedBitstreamUnitType
The codec-specific type of a bitstream unit.
Definition: cbs.h:43
uint8_t * write_buffer
Write buffer.
Definition: cbs.h:220
size_t data_bit_padding
The number of bits which should be ignored in the final byte.
Definition: cbs.h:88
int ff_cbs_make_unit_refcounted(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Make the content of a unit refcounted.
Definition: cbs.c:947
Coded bitstream unit structure.
Definition: cbs.h:66
ptrdiff_t size
Definition: opengl_enc.c:100
void * content
Pointer to the decomposed form of this unit.
Definition: cbs.h:103
CodedBitstreamUnit * units
Pointer to an array of units of length nb_units_allocated.
Definition: cbs.h:164
uint8_t * data
Pointer to the directly-parsable bitstream form of this unit.
Definition: cbs.h:77
size_t data_size
The number of bytes in the bitstream.
Definition: cbs.h:131
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: codec_id.h:46
int ff_cbs_alloc_unit_content(CodedBitstreamUnit *unit, size_t size, void(*free)(void *opaque, uint8_t *content))
Allocate a new internal content buffer of the given size in the unit.
enum AVCodecID ff_cbs_all_codec_ids[]
Table of all supported codec IDs.
Definition: cbs.c:52
size_t data_bit_padding
The number of bits which should be ignored in the final byte.
Definition: cbs.h:135
void * log_ctx
Logging context to be passed to all av_log() calls associated with this context.
Definition: cbs.h:175
int ff_cbs_write_packet(CodedBitstreamContext *ctx, AVPacket *pkt, CodedBitstreamFragment *frag)
Write the bitstream of a fragment to a packet.
Definition: cbs.c:403
int ff_cbs_insert_unit_content(CodedBitstreamFragment *frag, int position, CodedBitstreamUnitType type, void *content, AVBufferRef *content_buf)
Insert a new unit into a fragment with the given content.
Definition: cbs.c:721
AVFormatContext * ctx
Definition: movenc.c:48
int ff_cbs_read(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, const uint8_t *data, size_t size)
Read a bitstream from a memory region into a fragment, then split into units and decompose.
Definition: cbs.c:271
enum AVCodecID codec_id
Definition: vaapi_decode.c:369
int ff_cbs_init(CodedBitstreamContext **ctx, enum AVCodecID codec_id, void *log_ctx)
Create and initialise a new context for the given codec.
Definition: cbs.c:74
uint8_t * data
Pointer to the bitstream form of this fragment.
Definition: cbs.h:124
Libavcodec external API header.
int nb_decompose_unit_types
Length of the decompose_unit_types array.
Definition: cbs.h:203
Coded bitstream fragment structure, combining one or more units.
Definition: cbs.h:118
int trace_level
Log level to use for trace output.
Definition: cbs.h:214
void ff_cbs_fragment_free(CodedBitstreamFragment *frag)
Free the units array of a fragment in addition to what ff_cbs_fragment_reset does.
Definition: cbs.c:161
Context structure for coded bitstream operations.
Definition: cbs.h:170
int ff_cbs_read_packet(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, const AVPacket *pkt)
Read the data bitstream from a packet into a fragment, then split into units and decompose.
Definition: cbs.c:244
void ff_cbs_flush(CodedBitstreamContext *ctx)
Reset all internal state in a context.
Definition: cbs.c:115
AVBufferRef * content_ref
If content is reference counted, a reference to the buffer containing content.
Definition: cbs.h:108
refcounted data buffer API
int ff_cbs_make_unit_writable(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Make the content of a unit writable so that internal fields can be modified.
Definition: cbs.c:995
int nb_units_allocated
Number of allocated units.
Definition: cbs.h:156
int ff_cbs_alloc_unit_content2(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit)
Allocate a new internal content buffer matching the type of the unit.
Definition: cbs.c:853
void * priv_data
Internal codec-specific data.
Definition: cbs.h:191
A reference to a data buffer.
Definition: buffer.h:81
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:94
CodedBitstreamUnitType * decompose_unit_types
Array of unit types which should be decomposed when reading.
Definition: cbs.h:199
int ff_cbs_write_extradata(CodedBitstreamContext *ctx, AVCodecParameters *par, CodedBitstreamFragment *frag)
Write the bitstream of a fragment to the extradata in codec parameters.
Definition: cbs.c:378
size_t write_buffer_size
Definition: cbs.h:221
const struct CodedBitstreamType * codec
Internal codec-specific hooks.
Definition: cbs.h:180
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:141
This structure stores compressed data.
Definition: packet.h:340
int ff_cbs_insert_unit_data(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:757
size_t data_size
The number of bytes in the bitstream (including any padding bits in the final byte).
Definition: cbs.h:82
void ff_cbs_close(CodedBitstreamContext **ctx)
Close a context and free all internal state.
Definition: cbs.c:121