mirror of https://git.ffmpeg.org/ffmpeg.git
476 lines
17 KiB
C
476 lines
17 KiB
C
/*
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* copyright (c) 2001 Fabrice Bellard
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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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#ifndef AVFORMAT_AVIO_H
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#define AVFORMAT_AVIO_H
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/**
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* @file
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* @ingroup lavf_io
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* Buffered I/O operations
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*/
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#include <stdint.h>
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#include "libavutil/common.h"
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#include "libavutil/dict.h"
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#include "libavutil/log.h"
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#include "libavformat/version.h"
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#define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
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/**
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* Callback for checking whether to abort blocking functions.
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* AVERROR_EXIT is returned in this case by the interrupted
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* function. During blocking operations, callback is called with
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* opaque as parameter. If the callback returns 1, the
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* blocking operation will be aborted.
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*
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* No members can be added to this struct without a major bump, if
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* new elements have been added after this struct in AVFormatContext
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* or AVIOContext.
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*/
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typedef struct AVIOInterruptCB {
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int (*callback)(void*);
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void *opaque;
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} AVIOInterruptCB;
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/**
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* Bytestream IO Context.
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* New fields can be added to the end with minor version bumps.
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* Removal, reordering and changes to existing fields require a major
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* version bump.
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* sizeof(AVIOContext) must not be used outside libav*.
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*
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* @note None of the function pointers in AVIOContext should be called
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* directly, they should only be set by the client application
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* when implementing custom I/O. Normally these are set to the
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* function pointers specified in avio_alloc_context()
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*/
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typedef struct AVIOContext {
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/**
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* A class for private options.
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*
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* If this AVIOContext is created by avio_open2(), av_class is set and
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* passes the options down to protocols.
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*
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* If this AVIOContext is manually allocated, then av_class may be set by
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* the caller.
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*
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* warning -- this field can be NULL, be sure to not pass this AVIOContext
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* to any av_opt_* functions in that case.
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*/
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const AVClass *av_class;
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unsigned char *buffer; /**< Start of the buffer. */
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int buffer_size; /**< Maximum buffer size */
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unsigned char *buf_ptr; /**< Current position in the buffer */
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unsigned char *buf_end; /**< End of the data, may be less than
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buffer+buffer_size if the read function returned
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less data than requested, e.g. for streams where
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no more data has been received yet. */
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void *opaque; /**< A private pointer, passed to the read/write/seek/...
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functions. */
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int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
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int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
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int64_t (*seek)(void *opaque, int64_t offset, int whence);
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int64_t pos; /**< position in the file of the current buffer */
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int must_flush; /**< true if the next seek should flush */
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int eof_reached; /**< true if eof reached */
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int write_flag; /**< true if open for writing */
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int max_packet_size;
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unsigned long checksum;
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unsigned char *checksum_ptr;
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unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
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int error; /**< contains the error code or 0 if no error happened */
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/**
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* Pause or resume playback for network streaming protocols - e.g. MMS.
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*/
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int (*read_pause)(void *opaque, int pause);
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/**
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* Seek to a given timestamp in stream with the specified stream_index.
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* Needed for some network streaming protocols which don't support seeking
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* to byte position.
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*/
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int64_t (*read_seek)(void *opaque, int stream_index,
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int64_t timestamp, int flags);
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/**
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* A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
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*/
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int seekable;
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/**
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* max filesize, used to limit allocations
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* This field is internal to libavformat and access from outside is not allowed.
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*/
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int64_t maxsize;
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/**
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* avio_read and avio_write should if possible be satisfied directly
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* instead of going through a buffer, and avio_seek will always
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* call the underlying seek function directly.
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*/
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int direct;
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/**
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* Bytes read statistic
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* This field is internal to libavformat and access from outside is not allowed.
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*/
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int64_t bytes_read;
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/**
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* seek statistic
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* This field is internal to libavformat and access from outside is not allowed.
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*/
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int seek_count;
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} AVIOContext;
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/* unbuffered I/O */
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/**
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* Return AVIO_FLAG_* access flags corresponding to the access permissions
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* of the resource in url, or a negative value corresponding to an
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* AVERROR code in case of failure. The returned access flags are
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* masked by the value in flags.
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*
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* @note This function is intrinsically unsafe, in the sense that the
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* checked resource may change its existence or permission status from
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* one call to another. Thus you should not trust the returned value,
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* unless you are sure that no other processes are accessing the
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* checked resource.
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*/
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int avio_check(const char *url, int flags);
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/**
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* Allocate and initialize an AVIOContext for buffered I/O. It must be later
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* freed with av_free().
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*
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* @param buffer Memory block for input/output operations via AVIOContext.
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* The buffer must be allocated with av_malloc() and friends.
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* @param buffer_size The buffer size is very important for performance.
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* For protocols with fixed blocksize it should be set to this blocksize.
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* For others a typical size is a cache page, e.g. 4kb.
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* @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
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* @param opaque An opaque pointer to user-specific data.
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* @param read_packet A function for refilling the buffer, may be NULL.
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* @param write_packet A function for writing the buffer contents, may be NULL.
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* The function may not change the input buffers content.
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* @param seek A function for seeking to specified byte position, may be NULL.
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*
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* @return Allocated AVIOContext or NULL on failure.
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*/
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AVIOContext *avio_alloc_context(
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unsigned char *buffer,
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int buffer_size,
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int write_flag,
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void *opaque,
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int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
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int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
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int64_t (*seek)(void *opaque, int64_t offset, int whence));
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void avio_w8(AVIOContext *s, int b);
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void avio_write(AVIOContext *s, const unsigned char *buf, int size);
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void avio_wl64(AVIOContext *s, uint64_t val);
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void avio_wb64(AVIOContext *s, uint64_t val);
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void avio_wl32(AVIOContext *s, unsigned int val);
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void avio_wb32(AVIOContext *s, unsigned int val);
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void avio_wl24(AVIOContext *s, unsigned int val);
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void avio_wb24(AVIOContext *s, unsigned int val);
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void avio_wl16(AVIOContext *s, unsigned int val);
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void avio_wb16(AVIOContext *s, unsigned int val);
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/**
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* Write a NULL-terminated string.
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* @return number of bytes written.
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*/
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int avio_put_str(AVIOContext *s, const char *str);
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/**
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* Convert an UTF-8 string to UTF-16LE and write it.
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* @return number of bytes written.
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*/
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int avio_put_str16le(AVIOContext *s, const char *str);
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/**
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* Passing this as the "whence" parameter to a seek function causes it to
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* return the filesize without seeking anywhere. Supporting this is optional.
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* If it is not supported then the seek function will return <0.
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*/
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#define AVSEEK_SIZE 0x10000
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/**
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* Oring this flag as into the "whence" parameter to a seek function causes it to
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* seek by any means (like reopening and linear reading) or other normally unreasonble
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* means that can be extreemly slow.
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* This may be ignored by the seek code.
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*/
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#define AVSEEK_FORCE 0x20000
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/**
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* fseek() equivalent for AVIOContext.
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* @return new position or AVERROR.
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*/
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int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
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/**
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* Skip given number of bytes forward
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* @return new position or AVERROR.
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*/
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int64_t avio_skip(AVIOContext *s, int64_t offset);
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/**
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* ftell() equivalent for AVIOContext.
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* @return position or AVERROR.
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*/
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static av_always_inline int64_t avio_tell(AVIOContext *s)
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{
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return avio_seek(s, 0, SEEK_CUR);
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}
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/**
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* Get the filesize.
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* @return filesize or AVERROR
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*/
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int64_t avio_size(AVIOContext *s);
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/**
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* feof() equivalent for AVIOContext.
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* @return non zero if and only if end of file
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*/
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int url_feof(AVIOContext *s);
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/** @warning currently size is limited */
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int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
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/**
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* Force flushing of buffered data to the output s.
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*
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* Force the buffered data to be immediately written to the output,
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* without to wait to fill the internal buffer.
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*/
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void avio_flush(AVIOContext *s);
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/**
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* Read size bytes from AVIOContext into buf.
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* @return number of bytes read or AVERROR
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*/
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int avio_read(AVIOContext *s, unsigned char *buf, int size);
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/**
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* @name Functions for reading from AVIOContext
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* @{
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*
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* @note return 0 if EOF, so you cannot use it if EOF handling is
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* necessary
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*/
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int avio_r8 (AVIOContext *s);
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unsigned int avio_rl16(AVIOContext *s);
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unsigned int avio_rl24(AVIOContext *s);
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unsigned int avio_rl32(AVIOContext *s);
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uint64_t avio_rl64(AVIOContext *s);
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unsigned int avio_rb16(AVIOContext *s);
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unsigned int avio_rb24(AVIOContext *s);
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unsigned int avio_rb32(AVIOContext *s);
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uint64_t avio_rb64(AVIOContext *s);
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/**
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* @}
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*/
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/**
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* Read a string from pb into buf. The reading will terminate when either
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* a NULL character was encountered, maxlen bytes have been read, or nothing
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* more can be read from pb. The result is guaranteed to be NULL-terminated, it
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* will be truncated if buf is too small.
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* Note that the string is not interpreted or validated in any way, it
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* might get truncated in the middle of a sequence for multi-byte encodings.
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*
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* @return number of bytes read (is always <= maxlen).
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* If reading ends on EOF or error, the return value will be one more than
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* bytes actually read.
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*/
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int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
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/**
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* Read a UTF-16 string from pb and convert it to UTF-8.
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* The reading will terminate when either a null or invalid character was
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* encountered or maxlen bytes have been read.
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* @return number of bytes read (is always <= maxlen)
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*/
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int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
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int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
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/**
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* @name URL open modes
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* The flags argument to avio_open must be one of the following
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* constants, optionally ORed with other flags.
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* @{
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*/
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#define AVIO_FLAG_READ 1 /**< read-only */
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#define AVIO_FLAG_WRITE 2 /**< write-only */
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#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
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/**
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* @}
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*/
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/**
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* Use non-blocking mode.
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* If this flag is set, operations on the context will return
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* AVERROR(EAGAIN) if they can not be performed immediately.
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* If this flag is not set, operations on the context will never return
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* AVERROR(EAGAIN).
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* Note that this flag does not affect the opening/connecting of the
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* context. Connecting a protocol will always block if necessary (e.g. on
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* network protocols) but never hang (e.g. on busy devices).
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* Warning: non-blocking protocols is work-in-progress; this flag may be
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* silently ignored.
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*/
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#define AVIO_FLAG_NONBLOCK 8
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/**
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* Use direct mode.
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* avio_read and avio_write should if possible be satisfied directly
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* instead of going through a buffer, and avio_seek will always
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* call the underlying seek function directly.
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*/
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#define AVIO_FLAG_DIRECT 0x8000
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/**
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* Create and initialize a AVIOContext for accessing the
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* resource indicated by url.
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* @note When the resource indicated by url has been opened in
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* read+write mode, the AVIOContext can be used only for writing.
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*
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* @param s Used to return the pointer to the created AVIOContext.
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* In case of failure the pointed to value is set to NULL.
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* @param flags flags which control how the resource indicated by url
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* is to be opened
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* @return 0 in case of success, a negative value corresponding to an
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* AVERROR code in case of failure
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*/
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int avio_open(AVIOContext **s, const char *url, int flags);
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/**
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* Create and initialize a AVIOContext for accessing the
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* resource indicated by url.
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* @note When the resource indicated by url has been opened in
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* read+write mode, the AVIOContext can be used only for writing.
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*
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* @param s Used to return the pointer to the created AVIOContext.
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* In case of failure the pointed to value is set to NULL.
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* @param flags flags which control how the resource indicated by url
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* is to be opened
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* @param int_cb an interrupt callback to be used at the protocols level
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* @param options A dictionary filled with protocol-private options. On return
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* this parameter will be destroyed and replaced with a dict containing options
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* that were not found. May be NULL.
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* @return 0 in case of success, a negative value corresponding to an
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* AVERROR code in case of failure
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*/
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int avio_open2(AVIOContext **s, const char *url, int flags,
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const AVIOInterruptCB *int_cb, AVDictionary **options);
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/**
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* Close the resource accessed by the AVIOContext s and free it.
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* This function can only be used if s was opened by avio_open().
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*
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* The internal buffer is automatically flushed before closing the
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* resource.
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*
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* @return 0 on success, an AVERROR < 0 on error.
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* @see avio_closep
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*/
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int avio_close(AVIOContext *s);
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/**
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* Close the resource accessed by the AVIOContext *s, free it
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* and set the pointer pointing to it to NULL.
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* This function can only be used if s was opened by avio_open().
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*
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* The internal buffer is automatically flushed before closing the
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* resource.
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*
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* @return 0 on success, an AVERROR < 0 on error.
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* @see avio_close
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*/
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int avio_closep(AVIOContext **s);
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/**
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* Open a write only memory stream.
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*
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* @param s new IO context
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* @return zero if no error.
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*/
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int avio_open_dyn_buf(AVIOContext **s);
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/**
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* Return the written size and a pointer to the buffer. The buffer
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* must be freed with av_free().
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* Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
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*
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* @param s IO context
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* @param pbuffer pointer to a byte buffer
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* @return the length of the byte buffer
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*/
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int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
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/**
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* Iterate through names of available protocols.
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*
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* @param opaque A private pointer representing current protocol.
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* It must be a pointer to NULL on first iteration and will
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* be updated by successive calls to avio_enum_protocols.
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* @param output If set to 1, iterate over output protocols,
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* otherwise over input protocols.
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*
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* @return A static string containing the name of current protocol or NULL
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*/
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const char *avio_enum_protocols(void **opaque, int output);
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/**
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* Pause and resume playing - only meaningful if using a network streaming
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* protocol (e.g. MMS).
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* @param pause 1 for pause, 0 for resume
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*/
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int avio_pause(AVIOContext *h, int pause);
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/**
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* Seek to a given timestamp relative to some component stream.
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* Only meaningful if using a network streaming protocol (e.g. MMS.).
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* @param stream_index The stream index that the timestamp is relative to.
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* If stream_index is (-1) the timestamp should be in AV_TIME_BASE
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* units from the beginning of the presentation.
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* If a stream_index >= 0 is used and the protocol does not support
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* seeking based on component streams, the call will fail.
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* @param timestamp timestamp in AVStream.time_base units
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* or if there is no stream specified then in AV_TIME_BASE units.
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* @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
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* and AVSEEK_FLAG_ANY. The protocol may silently ignore
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* AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
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* fail if used and not supported.
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* @return >= 0 on success
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* @see AVInputFormat::read_seek
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*/
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int64_t avio_seek_time(AVIOContext *h, int stream_index,
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int64_t timestamp, int flags);
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#endif /* AVFORMAT_AVIO_H */
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