buffer.go

package avutil

/*
#cgo pkg-config: libavutil

#include "libavutil/buffer.h"
*/
import "C"
import (
	"unsafe"

	"github.com/Lensual/go-libav/ctypes"
)

/*
 * 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 <stddef.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).
 */
type CAVBuffer C.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.
 */
type CAVBufferRef C.AVBufferRef

//#region CAVBufferRef

func (br *CAVBufferRef) GetBuffer() *CAVBuffer {
	return (*CAVBuffer)(br.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.
 */
func (br *CAVBufferRef) GetData() unsafe.Pointer {
	return unsafe.Pointer(br.data)
}

/**
 * Size of data in bytes.
 */
func (br *CAVBufferRef) GetSize() ctypes.SizeT {
	return ctypes.SizeT(br.size)
}

//#endregion CAVBufferRef

//  /**
//   * 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(size_t size);

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

//  /**
//   * Ensure dst refers to the same data as src.
//   *
//   * When *dst is already equivalent to src, do nothing. Otherwise unreference dst
//   * and replace it with a new reference to src.
//   *
//   * @param dst Pointer to either a valid buffer reference or NULL. On success,
//   *            this will point to a buffer reference equivalent to src. On
//   *            failure, dst will be left untouched.
//   * @param src A buffer reference to replace dst with. May be NULL, then this
//   *            function is equivalent to av_buffer_unref(dst).
//   * @return 0 on success
//   *         AVERROR(ENOMEM) on memory allocation failure.
//   */
//  int av_buffer_replace(AVBufferRef **dst, const AVBufferRef *src);

//  /**
//   * @}
//   */

//  /**
//   * @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(size_t size, AVBufferRef* (*alloc)(size_t 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. May be NULL, then the default allocator will be
//   *              used (av_buffer_alloc()).
//   * @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. May be NULL.
//   * @return newly created buffer pool on success, NULL on error.
//   */
//  AVBufferPool *av_buffer_pool_init2(size_t size, void *opaque,
// 									AVBufferRef* (*alloc)(void *opaque, size_t 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);

//  /**
//   * Query the original opaque parameter of an allocated buffer in the pool.
//   *
//   * @param ref a buffer reference to a buffer returned by av_buffer_pool_get.
//   * @return the opaque parameter set by the buffer allocator function of the
//   *         buffer pool.
//   *
//   * @note the opaque parameter of ref is used by the buffer pool implementation,
//   * therefore you have to use this function to access the original opaque
//   * parameter of an allocated buffer.
//   */
//  void *av_buffer_pool_buffer_get_opaque(const AVBufferRef *ref);

//  /**
//   * @}
//   */

//  #endif /* AVUTIL_BUFFER_H */