2 * This file is part of FFmpeg.
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.
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.
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
19 #ifndef AVCODEC_CBS_INTERNAL_H
20 #define AVCODEC_CBS_INTERNAL_H
29 // Unit content is a simple structure.
31 // Unit content contains some references to other structures, but all
32 // managed via buffer reference counting. The descriptor defines the
33 // structure offsets of every buffer reference.
34 CBS_CONTENT_TYPE_INTERNAL_REFS,
35 // Unit content is something more complex. The descriptor defines
36 // special functions to manage the content.
37 CBS_CONTENT_TYPE_COMPLEX,
41 // Maximum number of unit types described by the same unit type
43 CBS_MAX_UNIT_TYPES = 3,
44 // Maximum number of reference buffer offsets in any one unit.
45 CBS_MAX_REF_OFFSETS = 2,
46 // Special value used in a unit type descriptor to indicate that it
47 // applies to a large range of types rather than a set of discrete
49 CBS_UNIT_TYPE_RANGE = -1,
52 typedef const struct CodedBitstreamUnitTypeDescriptor {
53 // Number of entries in the unit_types array, or the special value
54 // CBS_UNIT_TYPE_RANGE to indicate that the range fields should be
58 // Array of unit types that this entry describes.
59 const CodedBitstreamUnitType unit_types[CBS_MAX_UNIT_TYPES];
61 // Start and end of unit type range, used if nb_unit_types is
62 // CBS_UNIT_TYPE_RANGE.
63 const CodedBitstreamUnitType unit_type_range_start;
64 const CodedBitstreamUnitType unit_type_range_end;
66 // The type of content described.
67 enum CBSContentType content_type;
68 // The size of the structure which should be allocated to contain
69 // the decomposed content of this type of unit.
72 // Number of entries in the ref_offsets array. Only used if the
73 // content_type is CBS_CONTENT_TYPE_INTERNAL_REFS.
75 // The structure must contain two adjacent elements:
77 // AVBufferRef *field_ref;
78 // where field points to something in the buffer referred to by
79 // field_ref. This offset is then set to offsetof(struct, field).
80 size_t ref_offsets[CBS_MAX_REF_OFFSETS];
82 void (*content_free)(void *opaque, uint8_t *data);
83 int (*content_clone)(AVBufferRef **ref, CodedBitstreamUnit *unit);
84 } CodedBitstreamUnitTypeDescriptor;
86 typedef struct CodedBitstreamType {
87 enum AVCodecID codec_id;
89 // A class for the private data, used to declare private AVOptions.
90 // This field is NULL for types that do not declare any options.
91 // If this field is non-NULL, the first member of the filter private data
92 // must be a pointer to AVClass.
93 const AVClass *priv_class;
95 size_t priv_data_size;
97 // List of unit type descriptors for this codec.
98 // Terminated by a descriptor with nb_unit_types equal to zero.
99 const CodedBitstreamUnitTypeDescriptor *unit_types;
101 // Split frag->data into coded bitstream units, creating the
102 // frag->units array. Fill data but not content on each unit.
103 // The header argument should be set if the fragment came from
104 // a header block, which may require different parsing for some
105 // codecs (e.g. the AVCC header in H.264).
106 int (*split_fragment)(CodedBitstreamContext *ctx,
107 CodedBitstreamFragment *frag,
110 // Read the unit->data bitstream and decompose it, creating
112 int (*read_unit)(CodedBitstreamContext *ctx,
113 CodedBitstreamUnit *unit);
115 // Write the data bitstream from unit->content into pbc.
116 // Return value AVERROR(ENOSPC) indicates that pbc was too small.
117 int (*write_unit)(CodedBitstreamContext *ctx,
118 CodedBitstreamUnit *unit,
121 // Read the data from all of frag->units and assemble it into
122 // a bitstream for the whole fragment.
123 int (*assemble_fragment)(CodedBitstreamContext *ctx,
124 CodedBitstreamFragment *frag);
126 // Reset the codec internal state.
127 void (*flush)(CodedBitstreamContext *ctx);
129 // Free the codec internal state.
130 void (*close)(CodedBitstreamContext *ctx);
131 } CodedBitstreamType;
134 // Helper functions for trace output.
136 void ff_cbs_trace_header(CodedBitstreamContext *ctx,
139 void ff_cbs_trace_syntax_element(CodedBitstreamContext *ctx, int position,
140 const char *name, const int *subscripts,
141 const char *bitstring, int64_t value);
144 // Helper functions for read/write of common bitstream elements, including
145 // generation of trace output.
147 int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
148 int width, const char *name,
149 const int *subscripts, uint32_t *write_to,
150 uint32_t range_min, uint32_t range_max);
152 int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
153 int width, const char *name,
154 const int *subscripts, uint32_t value,
155 uint32_t range_min, uint32_t range_max);
157 int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc,
158 int width, const char *name,
159 const int *subscripts, int32_t *write_to,
160 int32_t range_min, int32_t range_max);
162 int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc,
163 int width, const char *name,
164 const int *subscripts, int32_t value,
165 int32_t range_min, int32_t range_max);
167 // The largest unsigned value representable in N bits, suitable for use as
168 // range_max in the above functions.
169 #define MAX_UINT_BITS(length) ((UINT64_C(1) << (length)) - 1)
171 // The largest signed value representable in N bits, suitable for use as
172 // range_max in the above functions.
173 #define MAX_INT_BITS(length) ((INT64_C(1) << ((length) - 1)) - 1)
175 // The smallest signed value representable in N bits, suitable for use as
176 // range_min in the above functions.
177 #define MIN_INT_BITS(length) (-(INT64_C(1) << ((length) - 1)))
180 #define CBS_UNIT_TYPE_POD(type, structure) { \
181 .nb_unit_types = 1, \
182 .unit_types = { type }, \
183 .content_type = CBS_CONTENT_TYPE_POD, \
184 .content_size = sizeof(structure), \
186 #define CBS_UNIT_TYPE_INTERNAL_REF(type, structure, ref_field) { \
187 .nb_unit_types = 1, \
188 .unit_types = { type }, \
189 .content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
190 .content_size = sizeof(structure), \
191 .nb_ref_offsets = 1, \
192 .ref_offsets = { offsetof(structure, ref_field) }, \
194 #define CBS_UNIT_TYPE_COMPLEX(type, structure, free_func) { \
195 .nb_unit_types = 1, \
196 .unit_types = { type }, \
197 .content_type = CBS_CONTENT_TYPE_COMPLEX, \
198 .content_size = sizeof(structure), \
199 .content_free = free_func, \
201 #define CBS_UNIT_TYPE_END_OF_LIST { .nb_unit_types = 0 }
204 extern const CodedBitstreamType ff_cbs_type_av1;
205 extern const CodedBitstreamType ff_cbs_type_h264;
206 extern const CodedBitstreamType ff_cbs_type_h265;
207 extern const CodedBitstreamType ff_cbs_type_jpeg;
208 extern const CodedBitstreamType ff_cbs_type_mpeg2;
209 extern const CodedBitstreamType ff_cbs_type_vp9;
212 #endif /* AVCODEC_CBS_INTERNAL_H */