2134
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1 /*
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2 * copyright (c) 2001 Fabrice Bellard
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3 *
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4 * This file is part of FFmpeg.
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5 *
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6 * FFmpeg is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
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8 * License as published by the Free Software Foundation; either
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9 * version 2.1 of the License, or (at your option) any later version.
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10 *
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11 * FFmpeg is distributed in the hope that it will be useful,
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12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 * Lesser General Public License for more details.
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15 *
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16 * You should have received a copy of the GNU Lesser General Public
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17 * License along with FFmpeg; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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19 */
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20 #ifndef AVFORMAT_AVIO_H
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21 #define AVFORMAT_AVIO_H
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22
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23 /**
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24 * @file
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25 * @ingroup lavf_io
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26 * Buffered I/O operations
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27 */
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28
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29 #include <stdint.h>
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30
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31 #include "../libavutil/common.h"
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32 #include "../libavutil/dict.h"
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33 #include "../libavutil/log.h"
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34
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35 #include "version.h"
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36
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37
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38 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
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39
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40 /**
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41 * Callback for checking whether to abort blocking functions.
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42 * AVERROR_EXIT is returned in this case by the interrupted
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43 * function. During blocking operations, callback is called with
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44 * opaque as parameter. If the callback returns 1, the
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45 * blocking operation will be aborted.
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46 *
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47 * No members can be added to this struct without a major bump, if
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48 * new elements have been added after this struct in AVFormatContext
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49 * or AVIOContext.
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50 */
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51 typedef struct AVIOInterruptCB {
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52 int (*callback)(void*);
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53 void *opaque;
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54 } AVIOInterruptCB;
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55
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56 /**
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57 * Bytestream IO Context.
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58 * New fields can be added to the end with minor version bumps.
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59 * Removal, reordering and changes to existing fields require a major
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60 * version bump.
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61 * sizeof(AVIOContext) must not be used outside libav*.
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62 *
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63 * @note None of the function pointers in AVIOContext should be called
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64 * directly, they should only be set by the client application
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65 * when implementing custom I/O. Normally these are set to the
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66 * function pointers specified in avio_alloc_context()
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67 */
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68 typedef struct AVIOContext {
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69 /**
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70 * A class for private options.
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71 *
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72 * If this AVIOContext is created by avio_open2(), av_class is set and
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73 * passes the options down to protocols.
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74 *
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75 * If this AVIOContext is manually allocated, then av_class may be set by
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76 * the caller.
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77 *
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78 * warning -- this field can be NULL, be sure to not pass this AVIOContext
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79 * to any av_opt_* functions in that case.
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80 */
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81 const AVClass *av_class;
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82 unsigned char *buffer; /**< Start of the buffer. */
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83 int buffer_size; /**< Maximum buffer size */
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84 unsigned char *buf_ptr; /**< Current position in the buffer */
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85 unsigned char *buf_end; /**< End of the data, may be less than
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86 buffer+buffer_size if the read function returned
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87 less data than requested, e.g. for streams where
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88 no more data has been received yet. */
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89 void *opaque; /**< A private pointer, passed to the read/write/seek/...
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90 functions. */
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91 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
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92 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
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93 int64_t (*seek)(void *opaque, int64_t offset, int whence);
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94 int64_t pos; /**< position in the file of the current buffer */
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95 int must_flush; /**< true if the next seek should flush */
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96 int eof_reached; /**< true if eof reached */
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97 int write_flag; /**< true if open for writing */
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98 int max_packet_size;
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99 unsigned long checksum;
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100 unsigned char *checksum_ptr;
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101 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
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102 int error; /**< contains the error code or 0 if no error happened */
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103 /**
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104 * Pause or resume playback for network streaming protocols - e.g. MMS.
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105 */
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106 int (*read_pause)(void *opaque, int pause);
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107 /**
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108 * Seek to a given timestamp in stream with the specified stream_index.
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109 * Needed for some network streaming protocols which don't support seeking
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110 * to byte position.
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111 */
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112 int64_t (*read_seek)(void *opaque, int stream_index,
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113 int64_t timestamp, int flags);
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114 /**
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115 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
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116 */
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117 int seekable;
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118
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119 /**
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120 * max filesize, used to limit allocations
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121 * This field is internal to libavformat and access from outside is not allowed.
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122 */
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123 int64_t maxsize;
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124
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125 /**
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126 * avio_read and avio_write should if possible be satisfied directly
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127 * instead of going through a buffer, and avio_seek will always
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128 * call the underlying seek function directly.
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129 */
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130 int direct;
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131
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132 /**
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133 * Bytes read statistic
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134 * This field is internal to libavformat and access from outside is not allowed.
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135 */
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136 int64_t bytes_read;
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137
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138 /**
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139 * seek statistic
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140 * This field is internal to libavformat and access from outside is not allowed.
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141 */
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142 int seek_count;
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143
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144 /**
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145 * writeout statistic
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146 * This field is internal to libavformat and access from outside is not allowed.
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147 */
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148 int writeout_count;
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149 } AVIOContext;
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150
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151 /* unbuffered I/O */
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152
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153 /**
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154 * Return AVIO_FLAG_* access flags corresponding to the access permissions
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155 * of the resource in url, or a negative value corresponding to an
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156 * AVERROR code in case of failure. The returned access flags are
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157 * masked by the value in flags.
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158 *
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159 * @note This function is intrinsically unsafe, in the sense that the
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160 * checked resource may change its existence or permission status from
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161 * one call to another. Thus you should not trust the returned value,
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162 * unless you are sure that no other processes are accessing the
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163 * checked resource.
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164 */
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165 int avio_check(const char *url, int flags);
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166
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167 /**
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168 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
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169 * freed with av_free().
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170 *
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171 * @param buffer Memory block for input/output operations via AVIOContext.
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172 * The buffer must be allocated with av_malloc() and friends.
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173 * @param buffer_size The buffer size is very important for performance.
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174 * For protocols with fixed blocksize it should be set to this blocksize.
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175 * For others a typical size is a cache page, e.g. 4kb.
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176 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
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177 * @param opaque An opaque pointer to user-specific data.
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178 * @param read_packet A function for refilling the buffer, may be NULL.
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179 * @param write_packet A function for writing the buffer contents, may be NULL.
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180 * The function may not change the input buffers content.
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181 * @param seek A function for seeking to specified byte position, may be NULL.
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182 *
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183 * @return Allocated AVIOContext or NULL on failure.
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184 */
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185 AVIOContext *avio_alloc_context(
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186 unsigned char *buffer,
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187 int buffer_size,
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188 int write_flag,
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189 void *opaque,
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190 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
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191 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
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192 int64_t (*seek)(void *opaque, int64_t offset, int whence));
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193
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194 void avio_w8(AVIOContext *s, int b);
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195 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
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196 void avio_wl64(AVIOContext *s, uint64_t val);
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197 void avio_wb64(AVIOContext *s, uint64_t val);
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198 void avio_wl32(AVIOContext *s, unsigned int val);
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199 void avio_wb32(AVIOContext *s, unsigned int val);
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200 void avio_wl24(AVIOContext *s, unsigned int val);
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201 void avio_wb24(AVIOContext *s, unsigned int val);
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202 void avio_wl16(AVIOContext *s, unsigned int val);
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203 void avio_wb16(AVIOContext *s, unsigned int val);
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204
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205 /**
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206 * Write a NULL-terminated string.
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207 * @return number of bytes written.
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208 */
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209 int avio_put_str(AVIOContext *s, const char *str);
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210
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211 /**
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212 * Convert an UTF-8 string to UTF-16LE and write it.
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213 * @return number of bytes written.
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214 */
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215 int avio_put_str16le(AVIOContext *s, const char *str);
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216
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217 /**
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218 * Passing this as the "whence" parameter to a seek function causes it to
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219 * return the filesize without seeking anywhere. Supporting this is optional.
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220 * If it is not supported then the seek function will return <0.
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221 */
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222 #define AVSEEK_SIZE 0x10000
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223
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224 /**
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225 * Oring this flag as into the "whence" parameter to a seek function causes it to
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226 * seek by any means (like reopening and linear reading) or other normally unreasonable
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227 * means that can be extremely slow.
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228 * This may be ignored by the seek code.
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229 */
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230 #define AVSEEK_FORCE 0x20000
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231
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232 /**
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233 * fseek() equivalent for AVIOContext.
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234 * @return new position or AVERROR.
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235 */
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236 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
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237
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238 /**
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239 * Skip given number of bytes forward
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240 * @return new position or AVERROR.
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241 */
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242 int64_t avio_skip(AVIOContext *s, int64_t offset);
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243
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244 /**
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245 * ftell() equivalent for AVIOContext.
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246 * @return position or AVERROR.
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247 */
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248 static av_always_inline int64_t avio_tell(AVIOContext *s)
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249 {
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250 return avio_seek(s, 0, SEEK_CUR);
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251 }
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252
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253 /**
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254 * Get the filesize.
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255 * @return filesize or AVERROR
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256 */
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257 int64_t avio_size(AVIOContext *s);
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258
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259 /**
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260 * feof() equivalent for AVIOContext.
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261 * @return non zero if and only if end of file
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262 */
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263 int url_feof(AVIOContext *s);
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264
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265 /** @warning currently size is limited */
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266 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
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267
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268 /**
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269 * Force flushing of buffered data to the output s.
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270 *
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271 * Force the buffered data to be immediately written to the output,
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272 * without to wait to fill the internal buffer.
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273 */
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274 void avio_flush(AVIOContext *s);
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275
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276 /**
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277 * Read size bytes from AVIOContext into buf.
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278 * @return number of bytes read or AVERROR
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279 */
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280 int avio_read(AVIOContext *s, unsigned char *buf, int size);
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281
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282 /**
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283 * @name Functions for reading from AVIOContext
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284 * @{
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285 *
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286 * @note return 0 if EOF, so you cannot use it if EOF handling is
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287 * necessary
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288 */
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289 int avio_r8 (AVIOContext *s);
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290 unsigned int avio_rl16(AVIOContext *s);
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291 unsigned int avio_rl24(AVIOContext *s);
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292 unsigned int avio_rl32(AVIOContext *s);
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293 uint64_t avio_rl64(AVIOContext *s);
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294 unsigned int avio_rb16(AVIOContext *s);
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295 unsigned int avio_rb24(AVIOContext *s);
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296 unsigned int avio_rb32(AVIOContext *s);
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297 uint64_t avio_rb64(AVIOContext *s);
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298 /**
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299 * @}
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300 */
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301
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302 /**
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303 * Read a string from pb into buf. The reading will terminate when either
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304 * a NULL character was encountered, maxlen bytes have been read, or nothing
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305 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
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306 * will be truncated if buf is too small.
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307 * Note that the string is not interpreted or validated in any way, it
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308 * might get truncated in the middle of a sequence for multi-byte encodings.
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309 *
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310 * @return number of bytes read (is always <= maxlen).
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311 * If reading ends on EOF or error, the return value will be one more than
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312 * bytes actually read.
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313 */
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314 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
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315
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316 /**
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317 * Read a UTF-16 string from pb and convert it to UTF-8.
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318 * The reading will terminate when either a null or invalid character was
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319 * encountered or maxlen bytes have been read.
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320 * @return number of bytes read (is always <= maxlen)
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321 */
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322 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
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323 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
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324
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325
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326 /**
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327 * @name URL open modes
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328 * The flags argument to avio_open must be one of the following
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329 * constants, optionally ORed with other flags.
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330 * @{
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331 */
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332 #define AVIO_FLAG_READ 1 /**< read-only */
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333 #define AVIO_FLAG_WRITE 2 /**< write-only */
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334 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
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335 /**
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336 * @}
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337 */
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338
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339 /**
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340 * Use non-blocking mode.
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341 * If this flag is set, operations on the context will return
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342 * AVERROR(EAGAIN) if they can not be performed immediately.
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343 * If this flag is not set, operations on the context will never return
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344 * AVERROR(EAGAIN).
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345 * Note that this flag does not affect the opening/connecting of the
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346 * context. Connecting a protocol will always block if necessary (e.g. on
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347 * network protocols) but never hang (e.g. on busy devices).
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348 * Warning: non-blocking protocols is work-in-progress; this flag may be
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349 * silently ignored.
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350 */
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351 #define AVIO_FLAG_NONBLOCK 8
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352
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353 /**
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354 * Use direct mode.
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355 * avio_read and avio_write should if possible be satisfied directly
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356 * instead of going through a buffer, and avio_seek will always
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357 * call the underlying seek function directly.
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358 */
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359 #define AVIO_FLAG_DIRECT 0x8000
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360
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361 /**
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362 * Create and initialize a AVIOContext for accessing the
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363 * resource indicated by url.
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364 * @note When the resource indicated by url has been opened in
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365 * read+write mode, the AVIOContext can be used only for writing.
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366 *
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367 * @param s Used to return the pointer to the created AVIOContext.
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368 * In case of failure the pointed to value is set to NULL.
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369 * @param flags flags which control how the resource indicated by url
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370 * is to be opened
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371 * @return 0 in case of success, a negative value corresponding to an
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372 * AVERROR code in case of failure
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373 */
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374 int avio_open(AVIOContext **s, const char *url, int flags);
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375
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376 /**
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377 * Create and initialize a AVIOContext for accessing the
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378 * resource indicated by url.
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379 * @note When the resource indicated by url has been opened in
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380 * read+write mode, the AVIOContext can be used only for writing.
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381 *
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382 * @param s Used to return the pointer to the created AVIOContext.
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383 * In case of failure the pointed to value is set to NULL.
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384 * @param flags flags which control how the resource indicated by url
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385 * is to be opened
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386 * @param int_cb an interrupt callback to be used at the protocols level
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387 * @param options A dictionary filled with protocol-private options. On return
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388 * this parameter will be destroyed and replaced with a dict containing options
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389 * that were not found. May be NULL.
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390 * @return 0 in case of success, a negative value corresponding to an
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391 * AVERROR code in case of failure
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392 */
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393 int avio_open2(AVIOContext **s, const char *url, int flags,
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394 const AVIOInterruptCB *int_cb, AVDictionary **options);
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395
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396 /**
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397 * Close the resource accessed by the AVIOContext s and free it.
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398 * This function can only be used if s was opened by avio_open().
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399 *
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400 * The internal buffer is automatically flushed before closing the
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401 * resource.
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402 *
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403 * @return 0 on success, an AVERROR < 0 on error.
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404 * @see avio_closep
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405 */
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406 int avio_close(AVIOContext *s);
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407
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408 /**
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409 * Close the resource accessed by the AVIOContext *s, free it
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410 * and set the pointer pointing to it to NULL.
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411 * This function can only be used if s was opened by avio_open().
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412 *
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413 * The internal buffer is automatically flushed before closing the
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414 * resource.
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415 *
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416 * @return 0 on success, an AVERROR < 0 on error.
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417 * @see avio_close
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418 */
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419 int avio_closep(AVIOContext **s);
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420
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421
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422 /**
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423 * Open a write only memory stream.
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424 *
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425 * @param s new IO context
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426 * @return zero if no error.
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427 */
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428 int avio_open_dyn_buf(AVIOContext **s);
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429
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430 /**
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431 * Return the written size and a pointer to the buffer. The buffer
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432 * must be freed with av_free().
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433 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
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434 *
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435 * @param s IO context
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436 * @param pbuffer pointer to a byte buffer
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437 * @return the length of the byte buffer
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438 */
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439 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
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440
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441 /**
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442 * Iterate through names of available protocols.
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443 *
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444 * @param opaque A private pointer representing current protocol.
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445 * It must be a pointer to NULL on first iteration and will
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446 * be updated by successive calls to avio_enum_protocols.
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447 * @param output If set to 1, iterate over output protocols,
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448 * otherwise over input protocols.
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449 *
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450 * @return A static string containing the name of current protocol or NULL
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451 */
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452 const char *avio_enum_protocols(void **opaque, int output);
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453
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454 /**
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455 * Pause and resume playing - only meaningful if using a network streaming
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456 * protocol (e.g. MMS).
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457 * @param pause 1 for pause, 0 for resume
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458 */
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459 int avio_pause(AVIOContext *h, int pause);
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460
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461 /**
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462 * Seek to a given timestamp relative to some component stream.
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463 * Only meaningful if using a network streaming protocol (e.g. MMS.).
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464 * @param stream_index The stream index that the timestamp is relative to.
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465 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
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466 * units from the beginning of the presentation.
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467 * If a stream_index >= 0 is used and the protocol does not support
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468 * seeking based on component streams, the call will fail.
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469 * @param timestamp timestamp in AVStream.time_base units
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470 * or if there is no stream specified then in AV_TIME_BASE units.
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471 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
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472 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
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473 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
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474 * fail if used and not supported.
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475 * @return >= 0 on success
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476 * @see AVInputFormat::read_seek
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477 */
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478 int64_t avio_seek_time(AVIOContext *h, int stream_index,
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479 int64_t timestamp, int flags);
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480
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481 #endif /* AVFORMAT_AVIO_H */
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