/* * 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_H#define AVCODEC_CBS_H #include <stddef.h>#include <stdint.h> #include "libavutil/buffer.h" #include "codec_id.h"#include "codec_par.h"#include "defs.h"#include "packet.h"  /* * This defines a framework for converting between a coded bitstream * and structures defining all individual syntax elements found in * such a stream. * * Conversion in both directions is possible.  Given a coded bitstream * (any meaningful fragment), it can be parsed and decomposed into * syntax elements stored in a set of codec-specific structures. * Similarly, given a set of those same codec-specific structures the * syntax elements can be serialised and combined to create a coded * bitstream. */ struct AVCodecContext;struct CodedBitstreamType; /** * The codec-specific type of a bitstream unit. * * AV1: obu_type * H.264 / AVC: nal_unit_type * H.265 / HEVC: nal_unit_type * JPEG: marker value (without 0xff prefix) * MPEG-2: start code value (without prefix) * VP9: unused, set to zero (every unit is a frame) */typedef uint32_t CodedBitstreamUnitType; /** * Coded bitstream unit structure. * * A bitstream unit the smallest element of a bitstream which * is meaningful on its own.  For example, an H.264 NAL unit. * * See the codec-specific header for the meaning of this for any * particular codec. */typedef struct CodedBitstreamUnit {    /**     * Codec-specific type of this unit.     */    CodedBitstreamUnitType type;     /**     * Pointer to the directly-parsable bitstream form of this unit.     *     * May be NULL if the unit currently only exists in decomposed form.     */    uint8_t *data;    /**     * The number of bytes in the bitstream (including any padding bits     * in the final byte).     */    size_t   data_size;    /**     * The number of bits which should be ignored in the final byte.     *     * This supports non-byte-aligned bitstreams.     */    size_t   data_bit_padding;    /**     * A reference to the buffer containing data.     *     * Must be set if data is not NULL.     */    AVBufferRef *data_ref;     /**     * Pointer to the decomposed form of this unit.     *     * The type of this structure depends on both the codec and the     * type of this unit.  May be NULL if the unit only exists in     * bitstream form.     */    void *content;    /**     * If content is reference counted, a RefStruct reference backing content.     * NULL if content is not reference counted.     */    void *content_ref;} CodedBitstreamUnit; /** * Coded bitstream fragment structure, combining one or more units. * * This is any sequence of units.  It need not form some greater whole, * though in many cases it will.  For example, an H.264 access unit, * which is composed of a sequence of H.264 NAL units. */typedef struct CodedBitstreamFragment {    /**     * Pointer to the bitstream form of this fragment.     *     * May be NULL if the fragment only exists as component units.     */    uint8_t *data;    /**     * The number of bytes in the bitstream.     *     * The number of bytes in the bitstream (including any padding bits     * in the final byte).     */    size_t   data_size;    /**     * The number of bits which should be ignored in the final byte.     */    size_t data_bit_padding;    /**     * A reference to the buffer containing data.     *     * Must be set if data is not NULL.     */    AVBufferRef *data_ref;     /**     * Number of units in this fragment.     *     * This may be zero if the fragment only exists in bitstream form     * and has not been decomposed.     */    int              nb_units;     /**     * Number of allocated units.     *     * Must always be >= nb_units; designed for internal use by cbs.     */     int             nb_units_allocated;     /**     * Pointer to an array of units of length nb_units_allocated.     * Only the first nb_units are valid.     *     * Must be NULL if nb_units_allocated is zero.     */    CodedBitstreamUnit *units;} CodedBitstreamFragment;  struct CodedBitstreamContext;struct GetBitContext;struct PutBitContext; /** * Callback type for read tracing. * * @param ctx         User-set trace context. * @param gbc         A GetBitContext set at the start of the syntax *                    element.  This is a copy, the callee does not *                    need to preserve it. * @param length      Length in bits of the syntax element. * @param name        String name of the syntax elements. * @param subscripts  If the syntax element is an array, a pointer to *                    an array of subscripts into the array. * @param value       Parsed value of the syntax element. */typedef void (*CBSTraceReadCallback)(void *trace_context,                                     struct GetBitContext *gbc,                                     int start_position,                                     const char *name,                                     const int *subscripts,                                     int64_t value); /** * Callback type for write tracing. * * @param ctx         User-set trace context. * @param pbc         A PutBitContext set at the end of the syntax *                    element.  The user must not modify this, but may *                    inspect it to determine state. * @param length      Length in bits of the syntax element. * @param name        String name of the syntax elements. * @param subscripts  If the syntax element is an array, a pointer to *                    an array of subscripts into the array. * @param value       Written value of the syntax element. */typedef void (*CBSTraceWriteCallback)(void *trace_context,                                      struct PutBitContext *pbc,                                      int start_position,                                      const char *name,                                      const int *subscripts,                                      int64_t value); /** * Context structure for coded bitstream operations. */typedef struct CodedBitstreamContext {    /**     * Logging context to be passed to all av_log() calls associated     * with this context.     */    void *log_ctx;     /**     * Internal codec-specific hooks.     */    const struct CodedBitstreamType *codec;     /**     * Internal codec-specific data.     *     * This contains any information needed when reading/writing     * bitsteams which will not necessarily be present in a fragment.     * For example, for H.264 it contains all currently visible     * parameter sets - they are required to determine the bitstream     * syntax but need not be present in every access unit.     */    void *priv_data;     /**     * Array of unit types which should be decomposed when reading.     *     * Types not in this list will be available in bitstream form only.     * If NULL, all supported types will be decomposed.     */    const CodedBitstreamUnitType *decompose_unit_types;    /**     * Length of the decompose_unit_types array.     */    int nb_decompose_unit_types;     /**     * Enable trace output during read/write operations.     */    int trace_enable;    /**     * Log level to use for default trace output.     *     * From AV_LOG_*; defaults to AV_LOG_TRACE.     */    int trace_level;    /**     * User context pointer to pass to trace callbacks.     */    void *trace_context;    /**     * Callback for read tracing.     *     * If tracing is enabled then this is called once for each syntax     * element parsed.     */    CBSTraceReadCallback  trace_read_callback;    /**     * Callback for write tracing.     *     * If tracing is enabled then this is called once for each syntax     * element written.     */    CBSTraceWriteCallback trace_write_callback;     /**     * Write buffer. Used as intermediate buffer when writing units.     * For internal use of cbs only.     */    uint8_t *write_buffer;    size_t   write_buffer_size;} CodedBitstreamContext;  /** * Table of all supported codec IDs. * * Terminated by AV_CODEC_ID_NONE. */extern const enum AVCodecID ff_cbs_all_codec_ids[];  /** * Create and initialise a new context for the given codec. */int ff_cbs_init(CodedBitstreamContext **ctx,                enum AVCodecID codec_id, void *log_ctx); /** * Reset all internal state in a context. */void ff_cbs_flush(CodedBitstreamContext *ctx); /** * Close a context and free all internal state. */void ff_cbs_close(CodedBitstreamContext **ctx);  /** * Read the extradata bitstream found in codec parameters into a * fragment, then split into units and decompose. * * This also updates the internal state, so will need to be called for * codecs with extradata to read parameter sets necessary for further * parsing even if the fragment itself is not desired. * * The fragment must have been zeroed or reset via ff_cbs_fragment_reset * before use. */int ff_cbs_read_extradata(CodedBitstreamContext *ctx,                          CodedBitstreamFragment *frag,                          const AVCodecParameters *par); /** * Read the extradata bitstream found in a codec context into a * fragment, then split into units and decompose. * * This acts identical to ff_cbs_read_extradata() for the case where * you already have a codec context. */int ff_cbs_read_extradata_from_codec(CodedBitstreamContext *ctx,                                     CodedBitstreamFragment *frag,                                     const struct AVCodecContext *avctx); int ff_cbs_read_packet_side_data(CodedBitstreamContext *ctx,                                 CodedBitstreamFragment *frag,                                 const AVPacket *pkt); /** * Read the data bitstream from a packet into a fragment, then * split into units and decompose. * * This also updates the internal state of the coded bitstream context * with any persistent data from the fragment which may be required to * read following fragments (e.g. parameter sets). * * The fragment must have been zeroed or reset via ff_cbs_fragment_reset * before use. */int ff_cbs_read_packet(CodedBitstreamContext *ctx,                       CodedBitstreamFragment *frag,                       const AVPacket *pkt); /** * Read a bitstream from a memory region into a fragment, then * split into units and decompose. * * This also updates the internal state of the coded bitstream context * with any persistent data from the fragment which may be required to * read following fragments (e.g. parameter sets). * * The fragment must have been zeroed or reset via ff_cbs_fragment_reset * before use. */int ff_cbs_read(CodedBitstreamContext *ctx,                CodedBitstreamFragment *frag,                const uint8_t *data, size_t size);  /** * Write the content of the fragment to its own internal buffer. * * Writes the content of all units and then assembles them into a new * data buffer.  When modifying the content of decomposed units, this * can be used to regenerate the bitstream form of units or the whole * fragment so that it can be extracted for other use. * * This also updates the internal state of the coded bitstream context * with any persistent data from the fragment which may be required to * write following fragments (e.g. parameter sets). */int ff_cbs_write_fragment_data(CodedBitstreamContext *ctx,                               CodedBitstreamFragment *frag); /** * Write the bitstream of a fragment to the extradata in codec parameters. * * Modifies context and fragment as ff_cbs_write_fragment_data does and * replaces any existing extradata in the structure. */int ff_cbs_write_extradata(CodedBitstreamContext *ctx,                           AVCodecParameters *par,                           CodedBitstreamFragment *frag); /** * Write the bitstream of a fragment to a packet. * * Modifies context and fragment as ff_cbs_write_fragment_data does. * * On success, the packet's buf is unreferenced and its buf, data and * size fields are set to the corresponding values from the newly updated * fragment; other fields are not touched.  On failure, the packet is not * touched at all. */int ff_cbs_write_packet(CodedBitstreamContext *ctx,                        AVPacket *pkt,                        CodedBitstreamFragment *frag);  /** * Free the units contained in a fragment as well as the fragment's * own data buffer, but not the units array itself. */void ff_cbs_fragment_reset(CodedBitstreamFragment *frag); /** * Free the units array of a fragment in addition to what * ff_cbs_fragment_reset does. */void ff_cbs_fragment_free(CodedBitstreamFragment *frag); /** * Allocate a new internal content buffer matching the type of the unit. * * The content will be zeroed. */int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx,                              CodedBitstreamUnit *unit); /** * Insert a new unit into a fragment with the given content. * * If content_ref is supplied, it has to be a RefStruct reference * backing content; the user keeps ownership of the supplied reference. * The content structure continues to be owned by the caller if * content_ref is not supplied. */int ff_cbs_insert_unit_content(CodedBitstreamFragment *frag,                               int position,                               CodedBitstreamUnitType type,                               void *content,                               void *content_ref); /** * Add a new unit to a fragment with the given data bitstream. * * If data_buf is not supplied then data must have been allocated with * av_malloc() and will on success become owned by the unit after this * call or freed on error. */int ff_cbs_append_unit_data(CodedBitstreamFragment *frag,                            CodedBitstreamUnitType type,                            uint8_t *data, size_t data_size,                            AVBufferRef *data_buf); /** * Delete a unit from a fragment and free all memory it uses. * * Requires position to be >= 0 and < frag->nb_units. */void ff_cbs_delete_unit(CodedBitstreamFragment *frag,                        int position);  /** * Make the content of a unit refcounted. * * If the unit is not refcounted, this will do a deep copy of the unit * content to new refcounted buffers. * * It is not valid to call this function on a unit which does not have * decomposed content. */int ff_cbs_make_unit_refcounted(CodedBitstreamContext *ctx,                                CodedBitstreamUnit *unit); /** * Make the content of a unit writable so that internal fields can be * modified. * * If it is known that there are no other references to the content of * the unit, does nothing and returns success.  Otherwise (including the * case where the unit content is not refcounted), it does a full clone * of the content (including any internal buffers) to make a new copy, * and replaces the existing references inside the unit with that. * * It is not valid to call this function on a unit which does not have * decomposed content. */int ff_cbs_make_unit_writable(CodedBitstreamContext *ctx,                              CodedBitstreamUnit *unit); 

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