| /* |
| * 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); |
| |
| /** |
| * 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, 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(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. 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(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); |
| |
| /** |
| * 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(AVBufferRef *ref); |
| |
| /** |
| * @} |
| */ |
| |
| #endif /* AVUTIL_BUFFER_H */ |