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3rdparty/ffmpeg/include/libavutil/fifo.h
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246
3rdparty/ffmpeg/include/libavutil/fifo.h
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/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* @ingroup lavu_fifo
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* A generic FIFO API
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*/
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#ifndef AVUTIL_FIFO_H
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#define AVUTIL_FIFO_H
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#include <stddef.h>
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#include <stdint.h>
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#include "attributes.h"
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#include "version.h"
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/**
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* @defgroup lavu_fifo AVFifo
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* @ingroup lavu_data
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*
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* @{
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* A generic FIFO API
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*/
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typedef struct AVFifo AVFifo;
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/**
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* Callback for writing or reading from a FIFO, passed to (and invoked from) the
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* av_fifo_*_cb() functions. It may be invoked multiple times from a single
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* av_fifo_*_cb() call and may process less data than the maximum size indicated
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* by nb_elems.
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*
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* @param opaque the opaque pointer provided to the av_fifo_*_cb() function
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* @param buf the buffer for reading or writing the data, depending on which
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* av_fifo_*_cb function is called
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* @param nb_elems On entry contains the maximum number of elements that can be
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* read from / written into buf. On success, the callback should
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* update it to contain the number of elements actually written.
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*
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* @return 0 on success, a negative error code on failure (will be returned from
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* the invoking av_fifo_*_cb() function)
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*/
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typedef int AVFifoCB(void *opaque, void *buf, size_t *nb_elems);
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/**
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* Automatically resize the FIFO on writes, so that the data fits. This
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* automatic resizing happens up to a limit that can be modified with
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* av_fifo_auto_grow_limit().
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*/
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#define AV_FIFO_FLAG_AUTO_GROW (1 << 0)
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/**
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* Allocate and initialize an AVFifo with a given element size.
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*
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* @param elems initial number of elements that can be stored in the FIFO
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* @param elem_size Size in bytes of a single element. Further operations on
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* the returned FIFO will implicitly use this element size.
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* @param flags a combination of AV_FIFO_FLAG_*
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*
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* @return newly-allocated AVFifo on success, a negative error code on failure
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*/
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AVFifo *av_fifo_alloc2(size_t elems, size_t elem_size,
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unsigned int flags);
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/**
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* @return Element size for FIFO operations. This element size is set at
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* FIFO allocation and remains constant during its lifetime
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*/
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size_t av_fifo_elem_size(const AVFifo *f);
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/**
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* Set the maximum size (in elements) to which the FIFO can be resized
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* automatically. Has no effect unless AV_FIFO_FLAG_AUTO_GROW is used.
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*/
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void av_fifo_auto_grow_limit(AVFifo *f, size_t max_elems);
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/**
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* @return number of elements available for reading from the given FIFO.
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*/
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size_t av_fifo_can_read(const AVFifo *f);
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/**
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* @return Number of elements that can be written into the given FIFO without
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* growing it.
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*
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* In other words, this number of elements or less is guaranteed to fit
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* into the FIFO. More data may be written when the
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* AV_FIFO_FLAG_AUTO_GROW flag was specified at FIFO creation, but this
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* may involve memory allocation, which can fail.
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*/
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size_t av_fifo_can_write(const AVFifo *f);
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/**
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* Enlarge an AVFifo.
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*
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* On success, the FIFO will be large enough to hold exactly
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* inc + av_fifo_can_read() + av_fifo_can_write()
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* elements. In case of failure, the old FIFO is kept unchanged.
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*
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* @param f AVFifo to resize
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* @param inc number of elements to allocate for, in addition to the current
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* allocated size
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* @return a non-negative number on success, a negative error code on failure
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*/
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int av_fifo_grow2(AVFifo *f, size_t inc);
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/**
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* Write data into a FIFO.
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*
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* In case nb_elems > av_fifo_can_write(f) and the AV_FIFO_FLAG_AUTO_GROW flag
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* was not specified at FIFO creation, nothing is written and an error
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* is returned.
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*
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* Calling function is guaranteed to succeed if nb_elems <= av_fifo_can_write(f).
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*
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* @param f the FIFO buffer
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* @param buf Data to be written. nb_elems * av_fifo_elem_size(f) bytes will be
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* read from buf on success.
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* @param nb_elems number of elements to write into FIFO
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*
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* @return a non-negative number on success, a negative error code on failure
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*/
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int av_fifo_write(AVFifo *f, const void *buf, size_t nb_elems);
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/**
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* Write data from a user-provided callback into a FIFO.
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*
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* @param f the FIFO buffer
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* @param read_cb Callback supplying the data to the FIFO. May be called
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* multiple times.
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* @param opaque opaque user data to be provided to read_cb
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* @param nb_elems Should point to the maximum number of elements that can be
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* written. Will be updated to contain the number of elements
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* actually written.
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*
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* @return non-negative number on success, a negative error code on failure
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*/
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int av_fifo_write_from_cb(AVFifo *f, AVFifoCB read_cb,
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void *opaque, size_t *nb_elems);
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/**
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* Read data from a FIFO.
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*
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* In case nb_elems > av_fifo_can_read(f), nothing is read and an error
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* is returned.
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*
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* @param f the FIFO buffer
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* @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
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* will be written into buf on success.
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* @param nb_elems number of elements to read from FIFO
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*
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* @return a non-negative number on success, a negative error code on failure
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*/
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int av_fifo_read(AVFifo *f, void *buf, size_t nb_elems);
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/**
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* Feed data from a FIFO into a user-provided callback.
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*
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* @param f the FIFO buffer
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* @param write_cb Callback the data will be supplied to. May be called
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* multiple times.
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* @param opaque opaque user data to be provided to write_cb
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* @param nb_elems Should point to the maximum number of elements that can be
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* read. Will be updated to contain the total number of elements
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* actually sent to the callback.
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*
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* @return non-negative number on success, a negative error code on failure
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*/
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int av_fifo_read_to_cb(AVFifo *f, AVFifoCB write_cb,
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void *opaque, size_t *nb_elems);
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/**
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* Read data from a FIFO without modifying FIFO state.
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*
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* Returns an error if an attempt is made to peek to nonexistent elements
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* (i.e. if offset + nb_elems is larger than av_fifo_can_read(f)).
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*
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* @param f the FIFO buffer
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* @param buf Buffer to store the data. nb_elems * av_fifo_elem_size(f) bytes
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* will be written into buf.
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* @param nb_elems number of elements to read from FIFO
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* @param offset number of initial elements to skip.
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*
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* @return a non-negative number on success, a negative error code on failure
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*/
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int av_fifo_peek(const AVFifo *f, void *buf, size_t nb_elems, size_t offset);
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/**
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* Feed data from a FIFO into a user-provided callback.
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*
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* @param f the FIFO buffer
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* @param write_cb Callback the data will be supplied to. May be called
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* multiple times.
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* @param opaque opaque user data to be provided to write_cb
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* @param nb_elems Should point to the maximum number of elements that can be
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* read. Will be updated to contain the total number of elements
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* actually sent to the callback.
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* @param offset number of initial elements to skip; offset + *nb_elems must not
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* be larger than av_fifo_can_read(f).
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*
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* @return a non-negative number on success, a negative error code on failure
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*/
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int av_fifo_peek_to_cb(const AVFifo *f, AVFifoCB write_cb, void *opaque,
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size_t *nb_elems, size_t offset);
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/**
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* Discard the specified amount of data from an AVFifo.
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* @param size number of elements to discard, MUST NOT be larger than
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* av_fifo_can_read(f)
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*/
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void av_fifo_drain2(AVFifo *f, size_t size);
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/*
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* Empty the AVFifo.
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* @param f AVFifo to reset
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*/
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void av_fifo_reset2(AVFifo *f);
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/**
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* Free an AVFifo and reset pointer to NULL.
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* @param f Pointer to an AVFifo to free. *f == NULL is allowed.
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*/
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void av_fifo_freep2(AVFifo **f);
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/**
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* @}
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*/
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#endif /* AVUTIL_FIFO_H */
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