FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
cbs.h
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 #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  */
52 typedef uint32_t CodedBitstreamUnitType;
53 
54 /**
55  * Coded bitstream unit structure.
56  *
57  * A bitstream unit the smallest element of a bitstream which
58  * is meaningful on its own. For example, an H.264 NAL unit.
59  *
60  * See the codec-specific header for the meaning of this for any
61  * particular codec.
62  */
63 typedef struct CodedBitstreamUnit {
64  /**
65  * Codec-specific type of this unit.
66  */
68 
69  /**
70  * Pointer to the directly-parsable bitstream form of this unit.
71  *
72  * May be NULL if the unit currently only exists in decomposed form.
73  */
75  /**
76  * The number of bytes in the bitstream (including any padding bits
77  * in the final byte).
78  */
79  size_t data_size;
80  /**
81  * The number of bits which should be ignored in the final byte.
82  *
83  * This supports non-byte-aligned bitstreams.
84  */
86  /**
87  * If data is reference counted, a reference to the buffer containing
88  * data. Null if data is not reference counted.
89  */
91 
92  /**
93  * Pointer to the decomposed form of this unit.
94  *
95  * The type of this structure depends on both the codec and the
96  * type of this unit. May be NULL if the unit only exists in
97  * bitstream form.
98  */
99  void *content;
100  /**
101  * If content is reference counted, a reference to the buffer containing
102  * content. Null if content is not reference counted.
103  */
106 
107 /**
108  * Coded bitstream fragment structure, combining one or more units.
109  *
110  * This is any sequence of units. It need not form some greater whole,
111  * though in many cases it will. For example, an H.264 access unit,
112  * which is composed of a sequence of H.264 NAL units.
113  */
114 typedef struct CodedBitstreamFragment {
115  /**
116  * Pointer to the bitstream form of this fragment.
117  *
118  * May be NULL if the fragment only exists as component units.
119  */
121  /**
122  * The number of bytes in the bitstream.
123  *
124  * The number of bytes in the bitstream (including any padding bits
125  * in the final byte).
126  */
127  size_t data_size;
128  /**
129  * The number of bits which should be ignored in the final byte.
130  */
132  /**
133  * If data is reference counted, a reference to the buffer containing
134  * data. Null if data is not reference counted.
135  */
137 
138  /**
139  * Number of units in this fragment.
140  *
141  * This may be zero if the fragment only exists in bitstream form
142  * and has not been decomposed.
143  */
144  int nb_units;
145  /**
146  * Pointer to an array of units of length nb_units.
147  *
148  * Must be NULL if nb_units is zero.
149  */
152 
153 /**
154  * Context structure for coded bitstream operations.
155  */
156 typedef struct CodedBitstreamContext {
157  /**
158  * Logging context to be passed to all av_log() calls associated
159  * with this context.
160  */
161  void *log_ctx;
162 
163  /**
164  * Internal codec-specific hooks.
165  */
166  const struct CodedBitstreamType *codec;
167 
168  /**
169  * Internal codec-specific data.
170  *
171  * This contains any information needed when reading/writing
172  * bitsteams which will not necessarily be present in a fragment.
173  * For example, for H.264 it contains all currently visible
174  * parameter sets - they are required to determine the bitstream
175  * syntax but need not be present in every access unit.
176  */
177  void *priv_data;
178 
179  /**
180  * Array of unit types which should be decomposed when reading.
181  *
182  * Types not in this list will be available in bitstream form only.
183  * If NULL, all supported types will be decomposed.
184  */
186  /**
187  * Length of the decompose_unit_types array.
188  */
190 
191  /**
192  * Enable trace output during read/write operations.
193  */
195  /**
196  * Log level to use for trace output.
197  *
198  * From AV_LOG_*; defaults to AV_LOG_TRACE.
199  */
202 
203 
204 /**
205  * Table of all supported codec IDs.
206  *
207  * Terminated by AV_CODEC_ID_NONE.
208  */
209 extern const enum AVCodecID ff_cbs_all_codec_ids[];
210 
211 
212 /**
213  * Create and initialise a new context for the given codec.
214  */
216  enum AVCodecID codec_id, void *log_ctx);
217 
218 /**
219  * Close a context and free all internal state.
220  */
222 
223 
224 /**
225  * Read the extradata bitstream found in codec parameters into a
226  * fragment, then split into units and decompose.
227  *
228  * This also updates the internal state, so will need to be called for
229  * codecs with extradata to read parameter sets necessary for further
230  * parsing even if the fragment itself is not desired.
231  */
234  const AVCodecParameters *par);
235 
236 /**
237  * Read the data bitstream from a packet into a fragment, then
238  * split into units and decompose.
239  *
240  * This also updates the internal state of the coded bitstream context
241  * with any persistent data from the fragment which may be required to
242  * read following fragments (e.g. parameter sets).
243  */
246  const AVPacket *pkt);
247 
248 /**
249  * Read a bitstream from a memory region into a fragment, then
250  * split into units and decompose.
251  *
252  * This also updates the internal state of the coded bitstream context
253  * with any persistent data from the fragment which may be required to
254  * read following fragments (e.g. parameter sets).
255  */
258  const uint8_t *data, size_t size);
259 
260 
261 /**
262  * Write the content of the fragment to its own internal buffer.
263  *
264  * Writes the content of all units and then assembles them into a new
265  * data buffer. When modifying the content of decomposed units, this
266  * can be used to regenerate the bitstream form of units or the whole
267  * fragment so that it can be extracted for other use.
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  * write following fragments (e.g. parameter sets).
272  */
274  CodedBitstreamFragment *frag);
275 
276 /**
277  * Write the bitstream of a fragment to the extradata in codec parameters.
278  *
279  * This replaces any existing extradata in the structure.
280  */
282  AVCodecParameters *par,
283  CodedBitstreamFragment *frag);
284 
285 /**
286  * Write the bitstream of a fragment to a packet.
287  */
289  AVPacket *pkt,
290  CodedBitstreamFragment *frag);
291 
292 
293 /**
294  * Free all allocated memory in a fragment.
295  */
297  CodedBitstreamFragment *frag);
298 
299 
300 /**
301  * Allocate a new internal content buffer of the given size in the unit.
302  *
303  * The content will be zeroed.
304  */
306  CodedBitstreamUnit *unit,
307  size_t size,
308  void (*free)(void *unit, uint8_t *content));
309 
310 /**
311  * Allocate a new internal data buffer of the given size in the unit.
312  *
313  * The data buffer will have input padding.
314  */
316  CodedBitstreamUnit *unit,
317  size_t size);
318 
319 /**
320  * Insert a new unit into a fragment with the given content.
321  *
322  * The content structure continues to be owned by the caller if
323  * content_buf is not supplied.
324  */
327  int position,
329  void *content,
330  AVBufferRef *content_buf);
331 
332 /**
333  * Insert a new unit into a fragment with the given data bitstream.
334  *
335  * If data_buf is not supplied then data must have been allocated with
336  * av_malloc() and will become owned by the unit after this call.
337  */
340  int position,
342  uint8_t *data, size_t data_size,
343  AVBufferRef *data_buf);
344 
345 /**
346  * Delete a unit from a fragment and free all memory it uses.
347  */
350  int position);
351 
352 
353 #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:261
int nb_units
Number of units in this fragment.
Definition: cbs.h:144
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx, CodedBitstreamUnit *unit, size_t size, void(*free)(void *unit, uint8_t *content))
Allocate a new internal content buffer of the given size in the unit.
CodedBitstreamUnitType type
Codec-specific type of this unit.
Definition: cbs.h:67
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:170
static AVPacket pkt
This struct describes the properties of an encoded stream.
Definition: avcodec.h:3876
int trace_enable
Enable trace output during read/write operations.
Definition: cbs.h:194
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:85
Coded bitstream unit structure.
Definition: cbs.h:63
ptrdiff_t size
Definition: opengl_enc.c:101
void * content
Pointer to the decomposed form of this unit.
Definition: cbs.h:99
CodedBitstreamUnit * units
Pointer to an array of units of length nb_units.
Definition: cbs.h:150
uint8_t * data
Pointer to the directly-parsable bitstream form of this unit.
Definition: cbs.h:74
size_t data_size
The number of bytes in the bitstream.
Definition: cbs.h:127
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:518
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:43
size_t data_bit_padding
The number of bits which should be ignored in the final byte.
Definition: cbs.h:131
void * log_ctx
Logging context to be passed to all av_log() calls associated with this context.
Definition: cbs.h:161
int ff_cbs_write_packet(CodedBitstreamContext *ctx, AVPacket *pkt, CodedBitstreamFragment *frag)
Write the bitstream of a fragment to a packet.
Definition: cbs.c:320
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:241
enum AVCodecID codec_id
Definition: vaapi_decode.c:362
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:56
uint8_t * data
Pointer to the bitstream form of this fragment.
Definition: cbs.h:120
void ff_cbs_fragment_uninit(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag)
Free all allocated memory in a fragment.
Definition: cbs.c:121
Libavcodec external API header.
int nb_decompose_unit_types
Length of the decompose_unit_types array.
Definition: cbs.h:189
Coded bitstream fragment structure, combining one or more units.
Definition: cbs.h:114
int trace_level
Log level to use for trace output.
Definition: cbs.h:200
GLint GLenum type
Definition: opengl_enc.c:105
Context structure for coded bitstream operations.
Definition: cbs.h:156
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:212
AVBufferRef * content_ref
If content is reference counted, a reference to the buffer containing content.
Definition: cbs.h:104
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:475
void * priv_data
Internal codec-specific data.
Definition: cbs.h:177
A reference to a data buffer.
Definition: buffer.h:81
AVBufferRef * data_ref
If data is reference counted, a reference to the buffer containing data.
Definition: cbs.h:90
CodedBitstreamUnitType * decompose_unit_types
Array of unit types which should be decomposed when reading.
Definition: cbs.h:185
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:295
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:555
const struct CodedBitstreamType * codec
Internal codec-specific hooks.
Definition: cbs.h:166
AVBufferRef * data_ref
If data is reference counted, a reference to the buffer containing data.
Definition: cbs.h:136
This structure stores compressed data.
Definition: avcodec.h:1407
int 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:592
size_t data_size
The number of bytes in the bitstream (including any padding bits in the final byte).
Definition: cbs.h:79
void ff_cbs_close(CodedBitstreamContext **ctx)
Close a context and free all internal state.
Definition: cbs.c:95