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			/*
			* 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
			*/

			/**
			* @file
			* @ingroup lavu_buffer
			* refcounted data buffer API
			*/

			#ifndef AVUTIL_BUFFER_H
			#define AVUTIL_BUFFER_H

			#include <stdint.h>

			/**
			* @defgroup lavu_buffer AVBuffer
			* @ingroup lavu_data
			*
			* @{
			* AVBuffer is an API for reference-counted data buffers.
			*
			* There are two core objects in this API -- AVBuffer and AVBufferRef. AVBuffer
			* represents the data buffer itself; it is opaque and not meant to be accessed
			* by the caller directly, but only through AVBufferRef. However, the caller may
			* e.g. compare two AVBuffer pointers to check whether two different references
			* are describing the same data buffer. AVBufferRef represents a single
			* reference to an AVBuffer and it is the object that may be manipulated by the
			* caller directly.
			*
			* There are two functions provided for creating a new AVBuffer with a single
			* reference -- av_buffer_alloc() to just allocate a new buffer, and
			* av_buffer_create() to wrap an existing array in an AVBuffer. From an existing
			* reference, additional references may be created with av_buffer_ref().
			* Use av_buffer_unref() to free a reference (this will automatically free the
			* data once all the references are freed).
			*
			* The convention throughout this API and the rest of FFmpeg is such that the
			* buffer is considered writable if there exists only one reference to it (and
			* it has not been marked as read-only). The av_buffer_is_writable() function is
			* provided to check whether this is true and av_buffer_make_writable() will
			* automatically create a new writable buffer when necessary.
			* Of course nothing prevents the calling code from violating this convention,
			* however that is safe only when all the existing references are under its
			* control.
			*
			* @note Referencing and unreferencing the buffers is thread-safe and thus
			* may be done from multiple threads simultaneously without any need for
			* additional locking.
			*
			* @note Two different references to the same buffer can point to different
			* parts of the buffer (i.e. their AVBufferRef.data will not be equal).
			*/

			/**
			* A reference counted buffer type. It is opaque and is meant to be used through
			* references (AVBufferRef).
			*/
			typedef struct AVBuffer AVBuffer;

			/**
			* A reference to a data buffer.
			*
			* The size of this struct is not a part of the public ABI and it is not meant
			* to be allocated directly.
			*/
			typedef struct AVBufferRef {
			AVBuffer *buffer;

			/**
			* The data buffer. It is considered writable if and only if
			* this is the only reference to the buffer, in which case
			* av_buffer_is_writable() returns 1.
			*/
			uint8_t *data;
			/**
			* Size of data in bytes.
			*/
			int size;
			} AVBufferRef;

			/**
			* Allocate an AVBuffer of the given size using av_malloc().
			*
			* @return an AVBufferRef of given size or NULL when out of memory
			*/
			AVBufferRef *av_buffer_alloc(int size);

			/**
			* Same as av_buffer_alloc(), except the returned buffer will be initialized
			* to zero.
			*/
			AVBufferRef *av_buffer_allocz(int size);

			/**
			* Always treat the buffer as read-only, even when it has only one
			* reference.
			*/
			#define AV_BUFFER_FLAG_READONLY (1 << 0)

			/**
			* Create an AVBuffer from an existing array.
			*
			* If this function is successful, data is owned by the AVBuffer. The caller may
			* only access data through the returned AVBufferRef and references derived from
			* it.
			* If this function fails, data is left untouched.
			* @param data data array
			* @param size size of data in bytes
			* @param free a callback for freeing this buffer's data
			* @param opaque parameter to be got for processing or passed to free
			* @param flags a combination of AV_BUFFER_FLAG_*
			*
			* @return an AVBufferRef referring to data on success, NULL on failure.
			*/
			AVBufferRef av_buffer_create(uint8_t data, int size,
			void (free)(void opaque, uint8_t *data),
			void *opaque, int flags);

			/**
			* Default free callback, which calls av_free() on the buffer data.
			* This function is meant to be passed to av_buffer_create(), not called
			* directly.
			*/
			void av_buffer_default_free(void opaque, uint8_t data);

			/**
			* Create a new reference to an AVBuffer.
			*
			* @return a new AVBufferRef referring to the same AVBuffer as buf or NULL on
			* failure.
			*/
			AVBufferRef av_buffer_ref(AVBufferRef buf);

			/**
			* Free a given reference and automatically free the buffer if there are no more
			* references to it.
			*
			* @param buf the reference to be freed. The pointer is set to NULL on return.
			*/
			void av_buffer_unref(AVBufferRef **buf);

			/**
			* @return 1 if the caller may write to the data referred to by buf (which is
			* true if and only if buf is the only reference to the underlying AVBuffer).
			* Return 0 otherwise.
			* A positive answer is valid until av_buffer_ref() is called on buf.
			*/
			int av_buffer_is_writable(const AVBufferRef *buf);

			/**
			* @return the opaque parameter set by av_buffer_create.
			*/
			void av_buffer_get_opaque(const AVBufferRef buf);

			int av_buffer_get_ref_count(const AVBufferRef *buf);

			/**
			* Create a writable reference from a given buffer reference, avoiding data copy
			* if possible.
			*
			* @param buf buffer reference to make writable. On success, buf is either left
			* untouched, or it is unreferenced and a new writable AVBufferRef is
			* written in its place. On failure, buf is left untouched.
			* @return 0 on success, a negative AVERROR on failure.
			*/
			int av_buffer_make_writable(AVBufferRef **buf);

			/**
			* Reallocate a given buffer.
			*
			* @param buf a buffer reference to reallocate. On success, buf will be
			* unreferenced and a new reference with the required size will be
			* written in its place. On failure buf will be left untouched. *buf
			* may be NULL, then a new buffer is allocated.
			* @param size required new buffer size.
			* @return 0 on success, a negative AVERROR on failure.
			*
			* @note the buffer is actually reallocated with av_realloc() only if it was
			* initially allocated through av_buffer_realloc(NULL) and there is only one
			* reference to it (i.e. the one passed to this function). In all other cases
			* a new buffer is allocated and the data is copied.
			*/
			int av_buffer_realloc(AVBufferRef **buf, int size);

			/**
			* @}
			*/

			/**
			* @defgroup lavu_bufferpool AVBufferPool
			* @ingroup lavu_data
			*
			* @{
			* AVBufferPool is an API for a lock-free thread-safe pool of AVBuffers.
			*
			* Frequently allocating and freeing large buffers may be slow. AVBufferPool is
			* meant to solve this in cases when the caller needs a set of buffers of the
			* same size (the most obvious use case being buffers for raw video or audio
			* frames).
			*
			* At the beginning, the user must call av_buffer_pool_init() to create the
			* buffer pool. Then whenever a buffer is needed, call av_buffer_pool_get() to
			* get a reference to a new buffer, similar to av_buffer_alloc(). This new
			* reference works in all aspects the same way as the one created by
			* av_buffer_alloc(). However, when the last reference to this buffer is
			* unreferenced, it is returned to the pool instead of being freed and will be
			* reused for subsequent av_buffer_pool_get() calls.
			*
			* When the caller is done with the pool and no longer needs to allocate any new
			* buffers, av_buffer_pool_uninit() must be called to mark the pool as freeable.
			* Once all the buffers are released, it will automatically be freed.
			*
			* Allocating and releasing buffers with this API is thread-safe as long as
			* either the default alloc callback is used, or the user-supplied one is
			* thread-safe.
			*/

			/**
			* The buffer pool. This structure is opaque and not meant to be accessed
			* directly. It is allocated with av_buffer_pool_init() and freed with
			* av_buffer_pool_uninit().
			*/
			typedef struct AVBufferPool AVBufferPool;

			/**
			* Allocate and initialize a buffer pool.
			*
			* @param size size of each buffer in this pool
			* @param alloc a function that will be used to allocate new buffers when the
			* pool is empty. May be NULL, then the default allocator will be used
			* (av_buffer_alloc()).
			* @return newly created buffer pool on success, NULL on error.
			*/
			AVBufferPool av_buffer_pool_init(int size, AVBufferRef (*alloc)(int size));

			/**
			* Allocate and initialize a buffer pool with a more complex allocator.
			*
			* @param size size of each buffer in this pool
			* @param opaque arbitrary user data used by the allocator
			* @param alloc a function that will be used to allocate new buffers when the
			* pool is empty.
			* @param pool_free a function that will be called immediately before the pool
			* is freed. I.e. after av_buffer_pool_uninit() is called
			* by the caller and all the frames are returned to the pool
			* and freed. It is intended to uninitialize the user opaque
			* data.
			* @return newly created buffer pool on success, NULL on error.
			*/
			AVBufferPool av_buffer_pool_init2(int size, void opaque,
			AVBufferRef* (alloc)(void opaque, int size),
			void (pool_free)(void opaque));

			/**
			* Mark the pool as being available for freeing. It will actually be freed only
			* once all the allocated buffers associated with the pool are released. Thus it
			* is safe to call this function while some of the allocated buffers are still
			* in use.
			*
			* @param pool pointer to the pool to be freed. It will be set to NULL.
			*/
			void av_buffer_pool_uninit(AVBufferPool **pool);

			/**
			* Allocate a new AVBuffer, reusing an old buffer from the pool when available.
			* This function may be called simultaneously from multiple threads.
			*
			* @return a reference to the new buffer on success, NULL on error.
			*/
			AVBufferRef av_buffer_pool_get(AVBufferPool pool);

			/**
			* @}
			*/

			#endif /* AVUTIL_BUFFER_H */