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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
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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 size_t priv_data_size;
91 // List of unit type descriptors for this codec.
92 // Terminated by a descriptor with nb_unit_types equal to zero.
93 const CodedBitstreamUnitTypeDescriptor *unit_types;
95 // Split frag->data into coded bitstream units, creating the
96 // frag->units array. Fill data but not content on each unit.
97 // The header argument should be set if the fragment came from
98 // a header block, which may require different parsing for some
99 // codecs (e.g. the AVCC header in H.264).
100 int (*split_fragment)(CodedBitstreamContext *ctx,
101 CodedBitstreamFragment *frag,
104 // Read the unit->data bitstream and decompose it, creating
106 int (*read_unit)(CodedBitstreamContext *ctx,
107 CodedBitstreamUnit *unit);
109 // Write the data bitstream from unit->content into pbc.
110 // Return value AVERROR(ENOSPC) indicates that pbc was too small.
111 int (*write_unit)(CodedBitstreamContext *ctx,
112 CodedBitstreamUnit *unit,
115 // Read the data from all of frag->units and assemble it into
116 // a bitstream for the whole fragment.
117 int (*assemble_fragment)(CodedBitstreamContext *ctx,
118 CodedBitstreamFragment *frag);
120 // Free the codec internal state.
121 void (*close)(CodedBitstreamContext *ctx);
122 } CodedBitstreamType;
125 // Helper functions for trace output.
127 void ff_cbs_trace_header(CodedBitstreamContext *ctx,
130 void ff_cbs_trace_syntax_element(CodedBitstreamContext *ctx, int position,
131 const char *name, const int *subscripts,
132 const char *bitstring, int64_t value);
135 // Helper functions for read/write of common bitstream elements, including
136 // generation of trace output.
138 int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
139 int width, const char *name,
140 const int *subscripts, uint32_t *write_to,
141 uint32_t range_min, uint32_t range_max);
143 int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
144 int width, const char *name,
145 const int *subscripts, uint32_t value,
146 uint32_t range_min, uint32_t range_max);
148 int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc,
149 int width, const char *name,
150 const int *subscripts, int32_t *write_to,
151 int32_t range_min, int32_t range_max);
153 int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc,
154 int width, const char *name,
155 const int *subscripts, int32_t value,
156 int32_t range_min, int32_t range_max);
158 // The largest unsigned value representable in N bits, suitable for use as
159 // range_max in the above functions.
160 #define MAX_UINT_BITS(length) ((UINT64_C(1) << (length)) - 1)
162 // The largest signed value representable in N bits, suitable for use as
163 // range_max in the above functions.
164 #define MAX_INT_BITS(length) ((INT64_C(1) << ((length) - 1)) - 1)
166 // The smallest signed value representable in N bits, suitable for use as
167 // range_min in the above functions.
168 #define MIN_INT_BITS(length) (-(INT64_C(1) << ((length) - 1)))
171 #define CBS_UNIT_TYPE_POD(type, structure) { \
172 .nb_unit_types = 1, \
173 .unit_types = { type }, \
174 .content_type = CBS_CONTENT_TYPE_POD, \
175 .content_size = sizeof(structure), \
177 #define CBS_UNIT_TYPE_INTERNAL_REF(type, structure, ref_field) { \
178 .nb_unit_types = 1, \
179 .unit_types = { type }, \
180 .content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
181 .content_size = sizeof(structure), \
182 .nb_ref_offsets = 1, \
183 .ref_offsets = { offsetof(structure, ref_field) }, \
185 #define CBS_UNIT_TYPE_COMPLEX(type, structure, free_func) { \
186 .nb_unit_types = 1, \
187 .unit_types = { type }, \
188 .content_type = CBS_CONTENT_TYPE_COMPLEX, \
189 .content_size = sizeof(structure), \
190 .content_free = free_func, \
192 #define CBS_UNIT_TYPE_END_OF_LIST { .nb_unit_types = 0 }
195 extern const CodedBitstreamType ff_cbs_type_av1;
196 extern const CodedBitstreamType ff_cbs_type_h264;
197 extern const CodedBitstreamType ff_cbs_type_h265;
198 extern const CodedBitstreamType ff_cbs_type_jpeg;
199 extern const CodedBitstreamType ff_cbs_type_mpeg2;
200 extern const CodedBitstreamType ff_cbs_type_vp9;
203 #endif /* AVCODEC_CBS_INTERNAL_H */