cbs: Refcount all the things!
[libav.git] / libavcodec / cbs.h
1 /*
2 * This file is part of Libav.
3 *
4 * Libav 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 * Libav 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 Libav; 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
43 struct CodedBitstreamType;
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 */
67 CodedBitstreamUnitType type;
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 */
74 uint8_t *data;
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 */
85 size_t data_bit_padding;
86 /**
87 * If data is reference counted, a reference to the buffer containing
88 * data. Null if data is not reference counted.
89 */
90 AVBufferRef *data_ref;
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 */
104 AVBufferRef *content_ref;
105 } CodedBitstreamUnit;
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 */
120 uint8_t *data;
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 */
131 size_t data_bit_padding;
132 /**
133 * If data is reference counted, a reference to the buffer containing
134 * data. Null if data is not reference counted.
135 */
136 AVBufferRef *data_ref;
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 */
150 CodedBitstreamUnit *units;
151 } CodedBitstreamFragment;
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 */
185 CodedBitstreamUnitType *decompose_unit_types;
186 /**
187 * Length of the decompose_unit_types array.
188 */
189 int nb_decompose_unit_types;
190
191 /**
192 * Enable trace output during read/write operations.
193 */
194 int trace_enable;
195 /**
196 * Log level to use for trace output.
197 *
198 * From AV_LOG_*; defaults to AV_LOG_TRACE.
199 */
200 int trace_level;
201 } CodedBitstreamContext;
202
203
204 /**
205 * Create and initialise a new context for the given codec.
206 */
207 int ff_cbs_init(CodedBitstreamContext **ctx,
208 enum AVCodecID codec_id, void *log_ctx);
209
210 /**
211 * Close a context and free all internal state.
212 */
213 void ff_cbs_close(CodedBitstreamContext **ctx);
214
215
216 /**
217 * Read the extradata bitstream found in codec parameters into a
218 * fragment, then split into units and decompose.
219 *
220 * This also updates the internal state, so will need to be called for
221 * codecs with extradata to read parameter sets necessary for further
222 * parsing even if the fragment itself is not desired.
223 */
224 int ff_cbs_read_extradata(CodedBitstreamContext *ctx,
225 CodedBitstreamFragment *frag,
226 const AVCodecParameters *par);
227
228 /**
229 * Read the data bitstream from a packet into a fragment, then
230 * split into units and decompose.
231 *
232 * This also updates the internal state of the coded bitstream context
233 * with any persistent data from the fragment which may be required to
234 * read following fragments (e.g. parameter sets).
235 */
236 int ff_cbs_read_packet(CodedBitstreamContext *ctx,
237 CodedBitstreamFragment *frag,
238 const AVPacket *pkt);
239
240 /**
241 * Read a bitstream from a memory region into a fragment, then
242 * split into units and decompose.
243 *
244 * This also updates the internal state of the coded bitstream context
245 * with any persistent data from the fragment which may be required to
246 * read following fragments (e.g. parameter sets).
247 */
248 int ff_cbs_read(CodedBitstreamContext *ctx,
249 CodedBitstreamFragment *frag,
250 const uint8_t *data, size_t size);
251
252
253 /**
254 * Write the content of the fragment to its own internal buffer.
255 *
256 * Writes the content of all units and then assembles them into a new
257 * data buffer. When modifying the content of decomposed units, this
258 * can be used to regenerate the bitstream form of units or the whole
259 * fragment so that it can be extracted for other use.
260 *
261 * This also updates the internal state of the coded bitstream context
262 * with any persistent data from the fragment which may be required to
263 * write following fragments (e.g. parameter sets).
264 */
265 int ff_cbs_write_fragment_data(CodedBitstreamContext *ctx,
266 CodedBitstreamFragment *frag);
267
268 /**
269 * Write the bitstream of a fragment to the extradata in codec parameters.
270 *
271 * This replaces any existing extradata in the structure.
272 */
273 int ff_cbs_write_extradata(CodedBitstreamContext *ctx,
274 AVCodecParameters *par,
275 CodedBitstreamFragment *frag);
276
277 /**
278 * Write the bitstream of a fragment to a packet.
279 */
280 int ff_cbs_write_packet(CodedBitstreamContext *ctx,
281 AVPacket *pkt,
282 CodedBitstreamFragment *frag);
283
284
285 /**
286 * Free all allocated memory in a fragment.
287 */
288 void ff_cbs_fragment_uninit(CodedBitstreamContext *ctx,
289 CodedBitstreamFragment *frag);
290
291
292 /**
293 * Allocate a new internal content buffer of the given size in the unit.
294 *
295 * The content will be zeroed.
296 */
297 int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx,
298 CodedBitstreamUnit *unit,
299 size_t size,
300 void (*free)(void *unit, uint8_t *content));
301
302 /**
303 * Allocate a new internal data buffer of the given size in the unit.
304 *
305 * The data buffer will have input padding.
306 */
307 int ff_cbs_alloc_unit_data(CodedBitstreamContext *ctx,
308 CodedBitstreamUnit *unit,
309 size_t size);
310
311 /**
312 * Insert a new unit into a fragment with the given content.
313 *
314 * The content structure continues to be owned by the caller if
315 * content_buf is not supplied.
316 */
317 int ff_cbs_insert_unit_content(CodedBitstreamContext *ctx,
318 CodedBitstreamFragment *frag,
319 int position,
320 CodedBitstreamUnitType type,
321 void *content,
322 AVBufferRef *content_buf);
323
324 /**
325 * Insert a new unit into a fragment with the given data bitstream.
326 *
327 * If data_buf is not supplied then data must have been allocated with
328 * av_malloc() and will become owned by the unit after this call.
329 */
330 int ff_cbs_insert_unit_data(CodedBitstreamContext *ctx,
331 CodedBitstreamFragment *frag,
332 int position,
333 CodedBitstreamUnitType type,
334 uint8_t *data, size_t data_size,
335 AVBufferRef *data_buf);
336
337 /**
338 * Delete a unit from a fragment and free all memory it uses.
339 */
340 int ff_cbs_delete_unit(CodedBitstreamContext *ctx,
341 CodedBitstreamFragment *frag,
342 int position);
343
344
345 #endif /* AVCODEC_CBS_H */