libavcodec/cbs_internal.h

   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_INTERNAL_H
  20 #define AVCODEC_CBS_INTERNAL_H
  21
  22 #include <stdint.h>
  23
  24 #include "libavutil/buffer.h"
  25 #include "libavutil/log.h"
  26
  27 #include "cbs.h"
  28 #include "codec_id.h"
  29 #include "get_bits.h"
  30 #include "put_bits.h"
  31
  32
  33 enum CBSContentType {
  34     // Unit content is a simple structure.
  35     CBS_CONTENT_TYPE_POD,
  36     // Unit content contains some references to other structures, but all
  37     // managed via buffer reference counting.  The descriptor defines the
  38     // structure offsets of every buffer reference.
  39     CBS_CONTENT_TYPE_INTERNAL_REFS,
  40     // Unit content is something more complex.  The descriptor defines
  41     // special functions to manage the content.
  42     CBS_CONTENT_TYPE_COMPLEX,
  43 };
  44
  45 enum {
  46       // Maximum number of unit types described by the same unit type
  47       // descriptor.
  48       CBS_MAX_UNIT_TYPES  = 3,
  49       // Maximum number of reference buffer offsets in any one unit.
  50       CBS_MAX_REF_OFFSETS = 2,
  51       // Special value used in a unit type descriptor to indicate that it
  52       // applies to a large range of types rather than a set of discrete
  53       // values.
  54       CBS_UNIT_TYPE_RANGE = -1,
  55 };
  56
  57 typedef const struct CodedBitstreamUnitTypeDescriptor {
  58     // Number of entries in the unit_types array, or the special value
  59     // CBS_UNIT_TYPE_RANGE to indicate that the range fields should be
  60     // used instead.
  61     int nb_unit_types;
  62
  63     // Array of unit types that this entry describes.
  64     const CodedBitstreamUnitType unit_types[CBS_MAX_UNIT_TYPES];
  65
  66     // Start and end of unit type range, used if nb_unit_types is
  67     // CBS_UNIT_TYPE_RANGE.
  68     const CodedBitstreamUnitType unit_type_range_start;
  69     const CodedBitstreamUnitType unit_type_range_end;
  70
  71     // The type of content described.
  72     enum CBSContentType content_type;
  73     // The size of the structure which should be allocated to contain
  74     // the decomposed content of this type of unit.
  75     size_t content_size;
  76
  77     // Number of entries in the ref_offsets array.  Only used if the
  78     // content_type is CBS_CONTENT_TYPE_INTERNAL_REFS.
  79     int nb_ref_offsets;
  80     // The structure must contain two adjacent elements:
  81     //   type        *field;
  82     //   AVBufferRef *field_ref;
  83     // where field points to something in the buffer referred to by
  84     // field_ref.  This offset is then set to offsetof(struct, field).
  85     size_t ref_offsets[CBS_MAX_REF_OFFSETS];
  86
  87     void (*content_free)(void *opaque, uint8_t *data);
  88     int  (*content_clone)(AVBufferRef **ref, CodedBitstreamUnit *unit);
  89 } CodedBitstreamUnitTypeDescriptor;
  90
  91 typedef struct CodedBitstreamType {
  92     enum AVCodecID codec_id;
  93
  94     // A class for the private data, used to declare private AVOptions.
  95     // This field is NULL for types that do not declare any options.
  96     // If this field is non-NULL, the first member of the filter private data
  97     // must be a pointer to AVClass.
  98     const AVClass *priv_class;
  99
 100     size_t priv_data_size;
 101
 102     // List of unit type descriptors for this codec.
 103     // Terminated by a descriptor with nb_unit_types equal to zero.
 104     const CodedBitstreamUnitTypeDescriptor *unit_types;
 105
 106     // Split frag->data into coded bitstream units, creating the
 107     // frag->units array.  Fill data but not content on each unit.
 108     // The header argument should be set if the fragment came from
 109     // a header block, which may require different parsing for some
 110     // codecs (e.g. the AVCC header in H.264).
 111     int (*split_fragment)(CodedBitstreamContext *ctx,
 112                           CodedBitstreamFragment *frag,
 113                           int header);
 114
 115     // Read the unit->data bitstream and decompose it, creating
 116     // unit->content.
 117     int (*read_unit)(CodedBitstreamContext *ctx,
 118                      CodedBitstreamUnit *unit);
 119
 120     // Write the data bitstream from unit->content into pbc.
 121     // Return value AVERROR(ENOSPC) indicates that pbc was too small.
 122     int (*write_unit)(CodedBitstreamContext *ctx,
 123                       CodedBitstreamUnit *unit,
 124                       PutBitContext *pbc);
 125
 126     // Read the data from all of frag->units and assemble it into
 127     // a bitstream for the whole fragment.
 128     int (*assemble_fragment)(CodedBitstreamContext *ctx,
 129                              CodedBitstreamFragment *frag);
 130
 131     // Reset the codec internal state.
 132     void (*flush)(CodedBitstreamContext *ctx);
 133
 134     // Free the codec internal state.
 135     void (*close)(CodedBitstreamContext *ctx);
 136 } CodedBitstreamType;
 137
 138
 139 // Helper functions for trace output.
 140
 141 void ff_cbs_trace_header(CodedBitstreamContext *ctx,
 142                          const char *name);
 143
 144 void ff_cbs_trace_syntax_element(CodedBitstreamContext *ctx, int position,
 145                                  const char *name, const int *subscripts,
 146                                  const char *bitstring, int64_t value);
 147
 148
 149 // Helper functions for read/write of common bitstream elements, including
 150 // generation of trace output.
 151
 152 int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
 153                          int width, const char *name,
 154                          const int *subscripts, uint32_t *write_to,
 155                          uint32_t range_min, uint32_t range_max);
 156
 157 int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
 158                           int width, const char *name,
 159                           const int *subscripts, uint32_t value,
 160                           uint32_t range_min, uint32_t range_max);
 161
 162 int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc,
 163                        int width, const char *name,
 164                        const int *subscripts, int32_t *write_to,
 165                        int32_t range_min, int32_t range_max);
 166
 167 int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc,
 168                         int width, const char *name,
 169                         const int *subscripts, int32_t value,
 170                         int32_t range_min, int32_t range_max);
 171
 172 // The largest unsigned value representable in N bits, suitable for use as
 173 // range_max in the above functions.
 174 #define MAX_UINT_BITS(length) ((UINT64_C(1) << (length)) - 1)
 175
 176 // The largest signed value representable in N bits, suitable for use as
 177 // range_max in the above functions.
 178 #define MAX_INT_BITS(length) ((INT64_C(1) << ((length) - 1)) - 1)
 179
 180 // The smallest signed value representable in N bits, suitable for use as
 181 // range_min in the above functions.
 182 #define MIN_INT_BITS(length) (-(INT64_C(1) << ((length) - 1)))
 183
 184
 185 #define CBS_UNIT_TYPE_POD(type, structure) { \
 186         .nb_unit_types  = 1, \
 187         .unit_types     = { type }, \
 188         .content_type   = CBS_CONTENT_TYPE_POD, \
 189         .content_size   = sizeof(structure), \
 190     }
 191 #define CBS_UNIT_TYPE_INTERNAL_REF(type, structure, ref_field) { \
 192         .nb_unit_types  = 1, \
 193         .unit_types     = { type }, \
 194         .content_type   = CBS_CONTENT_TYPE_INTERNAL_REFS, \
 195         .content_size   = sizeof(structure), \
 196         .nb_ref_offsets = 1, \
 197         .ref_offsets    = { offsetof(structure, ref_field) }, \
 198     }
 199 #define CBS_UNIT_TYPE_COMPLEX(type, structure, free_func) { \
 200         .nb_unit_types  = 1, \
 201         .unit_types     = { type }, \
 202         .content_type   = CBS_CONTENT_TYPE_COMPLEX, \
 203         .content_size   = sizeof(structure), \
 204         .content_free   = free_func, \
 205     }
 206 #define CBS_UNIT_TYPE_END_OF_LIST { .nb_unit_types = 0 }
 207
 208
 209 extern const CodedBitstreamType ff_cbs_type_av1;
 210 extern const CodedBitstreamType ff_cbs_type_h264;
 211 extern const CodedBitstreamType ff_cbs_type_h265;
 212 extern const CodedBitstreamType ff_cbs_type_jpeg;
 213 extern const CodedBitstreamType ff_cbs_type_mpeg2;
 214 extern const CodedBitstreamType ff_cbs_type_vp9;
 215
 216
 217 #endif /* AVCODEC_CBS_INTERNAL_H */