libavcodec/cbs.h - manifest_repos/ffmpeg - Git at Google

 /*
  * 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 "avcodec.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 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 reference to the buffer containing
      * content.  Null if content is not reference counted.
      */
     AVBufferRef *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;

 /**
  * 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.
      */
     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 trace output.
      *
      * From AV_LOG_*; defaults to AV_LOG_TRACE.
      */
     int trace_level;

     /**
      * 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 AVCodecContext *avctx);

 /**
  * 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 of the given size in the unit.
  *
  * The content will be zeroed.
  */
 int ff_cbs_alloc_unit_content(CodedBitstreamUnit *unit,
                               size_t size,
                               void (*free)(void *opaque, uint8_t *content));

 /**
  * Allocate a new internal content buffer matching the type of the unit.
  *
  * The content will be zeroed.
  */
 int ff_cbs_alloc_unit_content2(CodedBitstreamContext *ctx,
                                CodedBitstreamUnit *unit);


 /**
  * Allocate a new internal data buffer of the given size in the unit.
  *
  * The data buffer will have input padding.
  */
 int ff_cbs_alloc_unit_data(CodedBitstreamUnit *unit,
                            size_t size);

 /**
  * Insert a new unit into a fragment with the given content.
  *
  * The content structure continues to be owned by the caller if
  * content_buf is not supplied.
  */
 int ff_cbs_insert_unit_content(CodedBitstreamFragment *frag,
                                int position,
                                CodedBitstreamUnitType type,
                                void *content,
                                AVBufferRef *content_buf);

 /**
  * Insert a new unit into 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_insert_unit_data(CodedBitstreamFragment *frag,
                             int position,
                             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);


 #endif /* AVCODEC_CBS_H */
	/*
	* 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 "avcodec.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 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 reference to the buffer containing
	* content. Null if content is not reference counted.
	*/
	AVBufferRef *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;

	/**
	* 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.
	*/
	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 trace output.
	*
	* From AV_LOG_*; defaults to AV_LOG_TRACE.
	*/
	int trace_level;

	/**
	* 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 AVCodecContext *avctx);

	/**
	* 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 of the given size in the unit.
	*
	* The content will be zeroed.
	*/
	int ff_cbs_alloc_unit_content(CodedBitstreamUnit *unit,
	size_t size,
	void (free)(void opaque, uint8_t *content));

	/**
	* Allocate a new internal content buffer matching the type of the unit.
	*
	* The content will be zeroed.
	*/
	int ff_cbs_alloc_unit_content2(CodedBitstreamContext *ctx,
	CodedBitstreamUnit *unit);


	/**
	* Allocate a new internal data buffer of the given size in the unit.
	*
	* The data buffer will have input padding.
	*/
	int ff_cbs_alloc_unit_data(CodedBitstreamUnit *unit,
	size_t size);

	/**
	* Insert a new unit into a fragment with the given content.
	*
	* The content structure continues to be owned by the caller if
	* content_buf is not supplied.
	*/
	int ff_cbs_insert_unit_content(CodedBitstreamFragment *frag,
	int position,
	CodedBitstreamUnitType type,
	void *content,
	AVBufferRef *content_buf);

	/**
	* Insert a new unit into 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_insert_unit_data(CodedBitstreamFragment *frag,
	int position,
	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);


	#endif /* AVCODEC_CBS_H */