lavc: Add coded bitstream read/write API
[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 "avcodec.h"
26
27
28 struct CodedBitstreamType;
29
30 /**
31 * Coded bitstream unit structure.
32 *
33 * A bitstream unit the the smallest element of a bitstream which
34 * is meaningful on its own. For example, an H.264 NAL unit.
35 *
36 * See the codec-specific header for the meaning of this for any
37 * particular codec.
38 */
39 typedef struct CodedBitstreamUnit {
40 /**
41 * Codec-specific type of this unit.
42 */
43 uint32_t type;
44
45 /**
46 * Pointer to the bitstream form of this unit.
47 *
48 * May be NULL if the unit currently only exists in decomposed form.
49 */
50 uint8_t *data;
51 /**
52 * The number of bytes in the bitstream (including any padding bits
53 * in the final byte).
54 */
55 size_t data_size;
56 /**
57 * The number of bits which should be ignored in the final byte.
58 *
59 * This supports non-byte-aligned bitstreams.
60 */
61 size_t data_bit_padding;
62
63 /**
64 * Pointer to the decomposed form of this unit.
65 *
66 * The type of this structure depends on both the codec and the
67 * type of this unit. May be NULL if the unit only exists in
68 * bitstream form.
69 */
70 void *content;
71 /**
72 * Whether the content was supplied externally.
73 *
74 * If so, it should not be freed when freeing the unit.
75 */
76 int content_external;
77 } CodedBitstreamUnit;
78
79 /**
80 * Coded bitstream fragment structure, combining one or more units.
81 *
82 * This is any sequence of units. It need not form some greater whole,
83 * though in many cases it will. For example, an H.264 access unit,
84 * which is composed of a sequence of H.264 NAL units.
85 */
86 typedef struct CodedBitstreamFragment {
87 /**
88 * Pointer to the bitstream form of this fragment.
89 *
90 * May be NULL if the fragment only exists as component units.
91 */
92 uint8_t *data;
93 /**
94 * The number of bytes in the bitstream.
95 *
96 * The number of bytes in the bitstream (including any padding bits
97 * in the final byte).
98 */
99 size_t data_size;
100 /**
101 * The number of bits which should be ignored in the final byte.
102 */
103 size_t data_bit_padding;
104
105 /**
106 * Number of units in this fragment.
107 *
108 * This may be zero if the fragment only exists in bistream form
109 * and has not been decomposed.
110 */
111 int nb_units;
112 /**
113 * Pointer to an array of units of length nb_units.
114 *
115 * Must be NULL if nb_units is zero.
116 */
117 CodedBitstreamUnit *units;
118 } CodedBitstreamFragment;
119
120 /**
121 * Context structure for coded bitstream operations.
122 */
123 typedef struct CodedBitstreamContext {
124 /**
125 * Logging context to be passed to all av_log() calls associated
126 * with this context.
127 */
128 void *log_ctx;
129
130 /**
131 * Internal codec-specific hooks.
132 */
133 const struct CodedBitstreamType *codec;
134
135 /**
136 * Internal codec-specific data.
137 *
138 * This contains any information needed when reading/writing
139 * bitsteams which will not necessarily be present in a fragment.
140 * For example, for H.264 it contains all currently visible
141 * parameter sets - they are required to determine the bitstream
142 * syntax but need not be present in every access unit.
143 */
144 void *priv_data;
145
146 /**
147 * Array of unit types which should be decomposed when reading.
148 *
149 * Types not in this list will be available in bitstream form only.
150 * If NULL, all supported types will be decomposed.
151 */
152 uint32_t *decompose_unit_types;
153 /**
154 * Length of the decompose_unit_types array.
155 */
156 int nb_decompose_unit_types;
157
158 /**
159 * Enable trace output during read/write operations.
160 */
161 int trace_enable;
162 /**
163 * Log level to use for trace output.
164 *
165 * From AV_LOG_*; defaults to AV_LOG_TRACE.
166 */
167 int trace_level;
168 } CodedBitstreamContext;
169
170
171 /**
172 * Initialise a new context for the given codec.
173 */
174 int ff_cbs_init(CodedBitstreamContext *ctx,
175 enum AVCodecID codec_id, void *log_ctx);
176
177 /**
178 * Close a context and free all internal state.
179 */
180 void ff_cbs_close(CodedBitstreamContext *ctx);
181
182
183 /**
184 * Read the extradata bitstream found in codec parameters into a
185 * fragment, then split into units and decompose.
186 *
187 * This also updates the internal state, so will need to be called for
188 * codecs with extradata to read parameter sets necessary for further
189 * parsing even if the fragment itself is not desired.
190 */
191 int ff_cbs_read_extradata(CodedBitstreamContext *ctx,
192 CodedBitstreamFragment *frag,
193 const AVCodecParameters *par);
194
195 /**
196 * Read the data bitstream from a packet into a fragment, then
197 * split into units and decompose.
198 */
199 int ff_cbs_read_packet(CodedBitstreamContext *ctx,
200 CodedBitstreamFragment *frag,
201 const AVPacket *pkt);
202
203 /**
204 * Read a bitstream from a memory region into a fragment, then
205 * split into units and decompose.
206 */
207 int ff_cbs_read(CodedBitstreamContext *ctx,
208 CodedBitstreamFragment *frag,
209 const uint8_t *data, size_t size);
210
211
212 /**
213 * Write the content of the fragment to its own internal buffer.
214 *
215 * Writes the content of all units and then assembles them into a new
216 * data buffer. When modifying the content of decomposed units, this
217 * can be used to regenerate the bitstream form of units or the whole
218 * fragment so that it can be extracted for other use.
219 */
220 int ff_cbs_write_fragment_data(CodedBitstreamContext *ctx,
221 CodedBitstreamFragment *frag);
222
223 /**
224 * Write the bitstream of a fragment to the extradata in codec parameters.
225 */
226 int ff_cbs_write_extradata(CodedBitstreamContext *ctx,
227 AVCodecParameters *par,
228 CodedBitstreamFragment *frag);
229
230 /**
231 * Write the bitstream of a fragment to a packet.
232 */
233 int ff_cbs_write_packet(CodedBitstreamContext *ctx,
234 AVPacket *pkt,
235 CodedBitstreamFragment *frag);
236
237
238 /**
239 * Free all allocated memory in a fragment.
240 */
241 void ff_cbs_fragment_uninit(CodedBitstreamContext *ctx,
242 CodedBitstreamFragment *frag);
243
244
245 /**
246 * Insert a new unit into a fragment with the given content.
247 *
248 * The content structure continues to be owned by the caller, and
249 * will not be freed when the unit is.
250 */
251 int ff_cbs_insert_unit_content(CodedBitstreamContext *ctx,
252 CodedBitstreamFragment *frag,
253 int position, uint32_t type,
254 void *content);
255
256 /**
257 * Insert a new unit into a fragment with the given data bitstream.
258 *
259 * The data buffer will be owned by the unit after this operation.
260 */
261 int ff_cbs_insert_unit_data(CodedBitstreamContext *ctx,
262 CodedBitstreamFragment *frag,
263 int position, uint32_t type,
264 uint8_t *data, size_t data_size);
265
266 /**
267 * Delete a unit from a fragment and free all memory it uses.
268 */
269 int ff_cbs_delete_unit(CodedBitstreamContext *ctx,
270 CodedBitstreamFragment *frag,
271 int position);
272
273
274 #endif /* AVCODEC_CBS_H */