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
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 #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  * H.264 / AVC: nal_unit_type
49  * H.265 / HEVC: nal_unit_type
50  * MPEG-2: start code value (without prefix)
51  * VP9: unused, set to zero (every unit is a frame)
52  */
53 typedef uint32_t CodedBitstreamUnitType;
54 
55 /**
56  * Coded bitstream unit structure.
57  *
58  * A bitstream unit the smallest element of a bitstream which
59  * is meaningful on its own. For example, an H.264 NAL unit.
60  *
61  * See the codec-specific header for the meaning of this for any
62  * particular codec.
63  */
64 typedef struct CodedBitstreamUnit {
65  /**
66  * Codec-specific type of this unit.
67  */
69 
70  /**
71  * Pointer to the directly-parsable bitstream form of this unit.
72  *
73  * May be NULL if the unit currently only exists in decomposed form.
74  */
76  /**
77  * The number of bytes in the bitstream (including any padding bits
78  * in the final byte).
79  */
80  size_t data_size;
81  /**
82  * The number of bits which should be ignored in the final byte.
83  *
84  * This supports non-byte-aligned bitstreams.
85  */
87  /**
88  * A reference to the buffer containing data.
89  *
90  * Must be set if data is not NULL.
91  */
93 
94  /**
95  * Pointer to the decomposed form of this unit.
96  *
97  * The type of this structure depends on both the codec and the
98  * type of this unit. May be NULL if the unit only exists in
99  * bitstream form.
100  */
101  void *content;
102  /**
103  * If content is reference counted, a reference to the buffer containing
104  * content. Null if content is not reference counted.
105  */
108 
109 /**
110  * Coded bitstream fragment structure, combining one or more units.
111  *
112  * This is any sequence of units. It need not form some greater whole,
113  * though in many cases it will. For example, an H.264 access unit,
114  * which is composed of a sequence of H.264 NAL units.
115  */
116 typedef struct CodedBitstreamFragment {
117  /**
118  * Pointer to the bitstream form of this fragment.
119  *
120  * May be NULL if the fragment only exists as component units.
121  */
123  /**
124  * The number of bytes in the bitstream.
125  *
126  * The number of bytes in the bitstream (including any padding bits
127  * in the final byte).
128  */
129  size_t data_size;
130  /**
131  * The number of bits which should be ignored in the final byte.
132  */
134  /**
135  * A reference to the buffer containing data.
136  *
137  * Must be set if data is not NULL.
138  */
140 
141  /**
142  * Number of units in this fragment.
143  *
144  * This may be zero if the fragment only exists in bitstream form
145  * and has not been decomposed.
146  */
147  int nb_units;
148 
149  /**
150  * Number of allocated units.
151  *
152  * Must always be >= nb_units; designed for internal use by cbs.
153  */
155 
156  /**
157  * Pointer to an array of units of length nb_units_allocated.
158  * Only the first nb_units are valid.
159  *
160  * Must be NULL if nb_units_allocated is zero.
161  */
164 
165 /**
166  * Context structure for coded bitstream operations.
167  */
168 typedef struct CodedBitstreamContext {
169  /**
170  * Logging context to be passed to all av_log() calls associated
171  * with this context.
172  */
173  void *log_ctx;
174 
175  /**
176  * Internal codec-specific hooks.
177  */
178  const struct CodedBitstreamType *codec;
179 
180  /**
181  * Internal codec-specific data.
182  *
183  * This contains any information needed when reading/writing
184  * bitsteams which will not necessarily be present in a fragment.
185  * For example, for H.264 it contains all currently visible
186  * parameter sets - they are required to determine the bitstream
187  * syntax but need not be present in every access unit.
188  */
189  void *priv_data;
190 
191  /**
192  * Array of unit types which should be decomposed when reading.
193  *
194  * Types not in this list will be available in bitstream form only.
195  * If NULL, all supported types will be decomposed.
196  */
198  /**
199  * Length of the decompose_unit_types array.
200  */
202 
203  /**
204  * Enable trace output during read/write operations.
205  */
207  /**
208  * Log level to use for trace output.
209  *
210  * From AV_LOG_*; defaults to AV_LOG_TRACE.
211  */
214 
215 
216 /**
217  * Table of all supported codec IDs.
218  *
219  * Terminated by AV_CODEC_ID_NONE.
220  */
221 extern const enum AVCodecID ff_cbs_all_codec_ids[];
222 
223 
224 /**
225  * Create and initialise a new context for the given codec.
226  */
228  enum AVCodecID codec_id, void *log_ctx);
229 
230 /**
231  * Close a context and free all internal state.
232  */
234 
235 
236 /**
237  * Read the extradata bitstream found in codec parameters into a
238  * fragment, then split into units and decompose.
239  *
240  * This also updates the internal state, so will need to be called for
241  * codecs with extradata to read parameter sets necessary for further
242  * parsing even if the fragment itself is not desired.
243  *
244  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
245  * before use.
246  */
249  const AVCodecParameters *par);
250 
251 /**
252  * Read the data bitstream from a packet into a fragment, then
253  * split into units and decompose.
254  *
255  * This also updates the internal state of the coded bitstream context
256  * with any persistent data from the fragment which may be required to
257  * read following fragments (e.g. parameter sets).
258  *
259  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
260  * before use.
261  */
264  const AVPacket *pkt);
265 
266 /**
267  * Read a bitstream from a memory region into a fragment, then
268  * split into units and decompose.
269  *
270  * This also updates the internal state of the coded bitstream context
271  * with any persistent data from the fragment which may be required to
272  * read following fragments (e.g. parameter sets).
273  *
274  * The fragment must have been zeroed or reset via ff_cbs_fragment_reset
275  * before use.
276  */
279  const uint8_t *data, size_t size);
280 
281 
282 /**
283  * Write the content of the fragment to its own internal buffer.
284  *
285  * Writes the content of all units and then assembles them into a new
286  * data buffer. When modifying the content of decomposed units, this
287  * can be used to regenerate the bitstream form of units or the whole
288  * fragment so that it can be extracted for other use.
289  *
290  * This also updates the internal state of the coded bitstream context
291  * with any persistent data from the fragment which may be required to
292  * write following fragments (e.g. parameter sets).
293  */
295  CodedBitstreamFragment *frag);
296 
297 /**
298  * Write the bitstream of a fragment to the extradata in codec parameters.
299  *
300  * Modifies context and fragment as ff_cbs_write_fragment_data does and
301  * replaces any existing extradata in the structure.
302  */
304  AVCodecParameters *par,
305  CodedBitstreamFragment *frag);
306 
307 /**
308  * Write the bitstream of a fragment to a packet.
309  *
310  * Modifies context and fragment as ff_cbs_write_fragment_data does.
311  *
312  * On success, the packet's buf is unreferenced and its buf, data and
313  * size fields are set to the corresponding values from the newly updated
314  * fragment; other fields are not touched. On failure, the packet is not
315  * touched at all.
316  */
318  AVPacket *pkt,
319  CodedBitstreamFragment *frag);
320 
321 
322 /**
323  * Free the units contained in a fragment as well as the fragment's
324  * own data buffer, but not the units array itself.
325  */
327  CodedBitstreamFragment *frag);
328 
329 /**
330  * Free the units array of a fragment in addition to what
331  * ff_cbs_fragment_reset does.
332  */
334  CodedBitstreamFragment *frag);
335 
336 /**
337  * Allocate a new internal content buffer of the given size in the unit.
338  *
339  * The content will be zeroed.
340  */
342  CodedBitstreamUnit *unit,
343  size_t size,
344  void (*free)(void *opaque, uint8_t *content));
345 
346 /**
347  * Allocate a new internal data buffer of the given size in the unit.
348  *
349  * The data buffer will have input padding.
350  */
352  CodedBitstreamUnit *unit,
353  size_t size);
354 
355 /**
356  * Insert a new unit into a fragment with the given content.
357  *
358  * The content structure continues to be owned by the caller if
359  * content_buf is not supplied.
360  */
363  int position,
365  void *content,
366  AVBufferRef *content_buf);
367 
368 /**
369  * Insert a new unit into a fragment with the given data bitstream.
370  *
371  * If data_buf is not supplied then data must have been allocated with
372  * av_malloc() and will become owned by the unit after this call.
373  */
376  int position,
378  uint8_t *data, size_t data_size,
379  AVBufferRef *data_buf);
380 
381 /**
382  * Delete a unit from a fragment and free all memory it uses.
383  *
384  * Requires position to be >= 0 and < frag->nb_units.
385  */
388  int position);
389 
390 
391 #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:284
int nb_units
Number of units in this fragment.
Definition: cbs.h:147
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
void ff_cbs_fragment_reset(CodedBitstreamContext *ctx, 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:139
enum AVCodecID codec_id
Definition: qsv.c:77
CodedBitstreamUnitType type
Codec-specific type of this unit.
Definition: cbs.h:68
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:221
static AVPacket pkt
This struct describes the properties of an encoded stream.
Definition: avcodec.h:3960
int trace_enable
Enable trace output during read/write operations.
Definition: cbs.h:206
uint8_t
uint32_t CodedBitstreamUnitType
The codec-specific type of a bitstream unit.
Definition: cbs.h:43
size_t data_bit_padding
The number of bits which should be ignored in the final byte.
Definition: cbs.h:86
Coded bitstream unit structure.
Definition: cbs.h:64
ptrdiff_t size
Definition: opengl_enc.c:100
void * content
Pointer to the decomposed form of this unit.
Definition: cbs.h:101
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
void ff_cbs_delete_unit(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, int position)
Delete a unit from a fragment and free all memory it uses.
Definition: cbs.c:740
size_t data_size
The number of bytes in the bitstream.
Definition: cbs.h:129
int ff_cbs_insert_unit_content(CodedBitstreamContext *ctx, 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:666
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:215
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:133
void * log_ctx
Logging context to be passed to all av_log() calls associated with this context.
Definition: cbs.h:173
int ff_cbs_write_packet(CodedBitstreamContext *ctx, AVPacket *pkt, CodedBitstreamFragment *frag)
Write the bitstream of a fragment to a packet.
Definition: cbs.c:345
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:266
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:122
int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx, 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.
Libavcodec external API header.
int nb_decompose_unit_types
Length of the decompose_unit_types array.
Definition: cbs.h:201
Coded bitstream fragment structure, combining one or more units.
Definition: cbs.h:116
int trace_level
Log level to use for trace output.
Definition: cbs.h:212
Context structure for coded bitstream operations.
Definition: cbs.h:168
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:239
AVBufferRef * content_ref
If content is reference counted, a reference to the buffer containing content.
Definition: cbs.h:106
refcounted data buffer API
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
int nb_units_allocated
Number of allocated units.
Definition: cbs.h:154
void * priv_data
Internal codec-specific data.
Definition: cbs.h:189
A reference to a data buffer.
Definition: buffer.h:81
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:92
CodedBitstreamUnitType * decompose_unit_types
Array of unit types which should be decomposed when reading.
Definition: cbs.h:197
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:320
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
const struct CodedBitstreamType * codec
Internal codec-specific hooks.
Definition: cbs.h:178
void ff_cbs_fragment_free(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag)
Free the units array of a fragment in addition to what ff_cbs_fragment_reset does.
Definition: cbs.c:154
AVBufferRef * data_ref
A reference to the buffer containing data.
Definition: cbs.h:139
This structure stores compressed data.
Definition: avcodec.h:1457
size_t data_size
The number of bytes in the bitstream (including any padding bits in the final byte).
Definition: cbs.h:80
void ff_cbs_close(CodedBitstreamContext **ctx)
Close a context and free all internal state.
Definition: cbs.c:113