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FFmpeg/libavcodec/cbs_internal.h
Andreas Rheinhardt a105b11a9d avcodec/cbs: Add specialization for ff_cbs_(read|write)_unsigned()
These functions allow not only to read and write unsigned values,
but also to check ranges and to emit trace output which can be
beautified when processing arrays (indices like "[i]" are replaced
by their actual numbers).

Yet lots of callers actually only need something simpler:
Their range is only implicitly restricted by the amount
of bits used and they are not part of arrays, hence don't
need this beautification.

This commit adds specializations for these callers;
this is very beneficial size-wise (it reduced the size
of .text by 23312 bytes here), as a call is now cheaper.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2023-07-30 21:36:31 +02:00

270 lines
11 KiB
C

/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_CBS_INTERNAL_H
#define AVCODEC_CBS_INTERNAL_H
#include <stdint.h>
#include "libavutil/buffer.h"
#include "libavutil/log.h"
#include "cbs.h"
#include "codec_id.h"
#include "get_bits.h"
#include "put_bits.h"
enum CBSContentType {
// Unit content may contain some references to other structures, but all
// managed via buffer reference counting. The descriptor defines the
// structure offsets of every buffer reference.
CBS_CONTENT_TYPE_INTERNAL_REFS,
// Unit content is something more complex. The descriptor defines
// special functions to manage the content.
CBS_CONTENT_TYPE_COMPLEX,
};
enum {
// Maximum number of unit types described by the same non-range
// unit type descriptor.
CBS_MAX_LIST_UNIT_TYPES = 3,
// Maximum number of reference buffer offsets in any one unit.
CBS_MAX_REF_OFFSETS = 2,
// Special value used in a unit type descriptor to indicate that it
// applies to a large range of types rather than a set of discrete
// values.
CBS_UNIT_TYPE_RANGE = -1,
};
typedef const struct CodedBitstreamUnitTypeDescriptor {
// Number of entries in the unit_types array, or the special value
// CBS_UNIT_TYPE_RANGE to indicate that the range fields should be
// used instead.
int nb_unit_types;
union {
// Array of unit types that this entry describes.
CodedBitstreamUnitType list[CBS_MAX_LIST_UNIT_TYPES];
// Start and end of unit type range, used if nb_unit_types is
// CBS_UNIT_TYPE_RANGE.
struct {
CodedBitstreamUnitType start;
CodedBitstreamUnitType end;
} range;
} unit_type;
// The type of content described.
enum CBSContentType content_type;
// The size of the structure which should be allocated to contain
// the decomposed content of this type of unit.
size_t content_size;
union {
// This union's state is determined by content_type:
// ref for CBS_CONTENT_TYPE_INTERNAL_REFS,
// complex for CBS_CONTENT_TYPE_COMPLEX.
struct {
// Number of entries in the ref_offsets array.
// May be zero, then the structure is POD-like.
int nb_offsets;
// The structure must contain two adjacent elements:
// type *field;
// AVBufferRef *field_ref;
// where field points to something in the buffer referred to by
// field_ref. This offset is then set to offsetof(struct, field).
size_t offsets[CBS_MAX_REF_OFFSETS];
} ref;
struct {
void (*content_free)(void *opaque, uint8_t *data);
int (*content_clone)(AVBufferRef **ref, CodedBitstreamUnit *unit);
} complex;
} type;
} CodedBitstreamUnitTypeDescriptor;
typedef struct CodedBitstreamType {
enum AVCodecID codec_id;
// A class for the private data, used to declare private AVOptions.
// This field is NULL for types that do not declare any options.
// If this field is non-NULL, the first member of the filter private data
// must be a pointer to AVClass.
const AVClass *priv_class;
size_t priv_data_size;
// List of unit type descriptors for this codec.
// Terminated by a descriptor with nb_unit_types equal to zero.
const CodedBitstreamUnitTypeDescriptor *unit_types;
// Split frag->data into coded bitstream units, creating the
// frag->units array. Fill data but not content on each unit.
// The header argument should be set if the fragment came from
// a header block, which may require different parsing for some
// codecs (e.g. the AVCC header in H.264).
int (*split_fragment)(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int header);
// Read the unit->data bitstream and decompose it, creating
// unit->content.
int (*read_unit)(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit);
// Write the data bitstream from unit->content into pbc.
// Return value AVERROR(ENOSPC) indicates that pbc was too small.
int (*write_unit)(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc);
// Return 1 when the unit should be dropped according to 'skip',
// 0 otherwise.
int (*discarded_unit)(CodedBitstreamContext *ctx,
const CodedBitstreamUnit *unit,
enum AVDiscard skip);
// Read the data from all of frag->units and assemble it into
// a bitstream for the whole fragment.
int (*assemble_fragment)(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag);
// Reset the codec internal state.
void (*flush)(CodedBitstreamContext *ctx);
// Free the codec internal state.
void (*close)(CodedBitstreamContext *ctx);
} CodedBitstreamType;
// Helper functions for trace output.
void ff_cbs_trace_header(CodedBitstreamContext *ctx,
const char *name);
void ff_cbs_trace_syntax_element(CodedBitstreamContext *ctx, int position,
const char *name, const int *subscripts,
const char *bitstring, int64_t value);
// Helper functions for read/write of common bitstream elements, including
// generation of trace output. The simple functions are equivalent to
// their non-simple counterparts except that their range is unrestricted
// (i.e. only limited by the amount of bits used) and they lack
// the ability to use subscripts.
int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
int width, const char *name,
const int *subscripts, uint32_t *write_to,
uint32_t range_min, uint32_t range_max);
int ff_cbs_read_simple_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
int width, const char *name, uint32_t *write_to);
int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
int width, const char *name,
const int *subscripts, uint32_t value,
uint32_t range_min, uint32_t range_max);
int ff_cbs_write_simple_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
int width, const char *name, uint32_t value);
int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc,
int width, const char *name,
const int *subscripts, int32_t *write_to,
int32_t range_min, int32_t range_max);
int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc,
int width, const char *name,
const int *subscripts, int32_t value,
int32_t range_min, int32_t range_max);
// The largest unsigned value representable in N bits, suitable for use as
// range_max in the above functions.
#define MAX_UINT_BITS(length) ((UINT64_C(1) << (length)) - 1)
// The largest signed value representable in N bits, suitable for use as
// range_max in the above functions.
#define MAX_INT_BITS(length) ((INT64_C(1) << ((length) - 1)) - 1)
// The smallest signed value representable in N bits, suitable for use as
// range_min in the above functions.
#define MIN_INT_BITS(length) (-(INT64_C(1) << ((length) - 1)))
#define TYPE_LIST(...) { __VA_ARGS__ }
#define CBS_UNIT_TYPE_POD(type_, structure) { \
.nb_unit_types = 1, \
.unit_type.list = { type_ }, \
.content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
.content_size = sizeof(structure), \
.type.ref = { .nb_offsets = 0 }, \
}
#define CBS_UNIT_RANGE_POD(range_start, range_end, structure) { \
.nb_unit_types = CBS_UNIT_TYPE_RANGE, \
.unit_type.range.start = range_start, \
.unit_type.range.end = range_end, \
.content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
.content_size = sizeof(structure), \
.type.ref = { .nb_offsets = 0 }, \
}
#define CBS_UNIT_TYPES_INTERNAL_REF(types, structure, ref_field) { \
.nb_unit_types = FF_ARRAY_ELEMS((CodedBitstreamUnitType[])TYPE_LIST types), \
.unit_type.list = TYPE_LIST types, \
.content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
.content_size = sizeof(structure), \
.type.ref = { .nb_offsets = 1, \
.offsets = { offsetof(structure, ref_field) } }, \
}
#define CBS_UNIT_TYPE_INTERNAL_REF(type, structure, ref_field) \
CBS_UNIT_TYPES_INTERNAL_REF((type), structure, ref_field)
#define CBS_UNIT_RANGE_INTERNAL_REF(range_start, range_end, structure, ref_field) { \
.nb_unit_types = CBS_UNIT_TYPE_RANGE, \
.unit_type.range.start = range_start, \
.unit_type.range.end = range_end, \
.content_type = CBS_CONTENT_TYPE_INTERNAL_REFS, \
.content_size = sizeof(structure), \
.type.ref = { .nb_offsets = 1, \
.offsets = { offsetof(structure, ref_field) } }, \
}
#define CBS_UNIT_TYPES_COMPLEX(types, structure, free_func) { \
.nb_unit_types = FF_ARRAY_ELEMS((CodedBitstreamUnitType[])TYPE_LIST types), \
.unit_type.list = TYPE_LIST types, \
.content_type = CBS_CONTENT_TYPE_COMPLEX, \
.content_size = sizeof(structure), \
.type.complex = { .content_free = free_func }, \
}
#define CBS_UNIT_TYPE_COMPLEX(type, structure, free_func) \
CBS_UNIT_TYPES_COMPLEX((type), structure, free_func)
#define CBS_UNIT_TYPE_END_OF_LIST { .nb_unit_types = 0 }
extern const CodedBitstreamType ff_cbs_type_av1;
extern const CodedBitstreamType ff_cbs_type_h264;
extern const CodedBitstreamType ff_cbs_type_h265;
extern const CodedBitstreamType ff_cbs_type_h266;
extern const CodedBitstreamType ff_cbs_type_jpeg;
extern const CodedBitstreamType ff_cbs_type_mpeg2;
extern const CodedBitstreamType ff_cbs_type_vp9;
#endif /* AVCODEC_CBS_INTERNAL_H */