/*
  * copyright (c) 2001 Fabrice Bellard
  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #ifndef AVFORMAT_AVIO_H
 #define AVFORMAT_AVIO_H

 /**

  * @file

  * Buffered I/O operations

  */
 

 #include <stdint.h>
 

 #include "libavutil/common.h"

 #include "libavutil/log.h"

 #include "libavformat/version.h"
 

 
 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
 
 /**
  * Bytestream IO Context.
  * New fields can be added to the end with minor version bumps.
  * Removal, reordering and changes to existing fields require a major
  * version bump.
  * sizeof(AVIOContext) must not be used outside libav*.

  *
  * @note None of the function pointers in AVIOContext should be called
  *       directly, they should only be set by the client application
  *       when implementing custom I/O. Normally these are set to the
  *       function pointers specified in avio_alloc_context()

  */
 typedef struct {

     unsigned char *buffer;  /**< Start of the buffer. */
     int buffer_size;        /**< Maximum buffer size */
     unsigned char *buf_ptr; /**< Current position in the buffer */
     unsigned char *buf_end; /**< End of the data, may be less than
                                  buffer+buffer_size if the read function returned
                                  less data than requested, e.g. for streams where
                                  no more data has been received yet. */
     void *opaque;           /**< A private pointer, passed to the read/write/seek/...
                                  functions. */

     int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
     int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
     int64_t (*seek)(void *opaque, int64_t offset, int whence);

     int64_t pos;            /**< position in the file of the current buffer */
     int must_flush;         /**< true if the next seek should flush */
     int eof_reached;        /**< true if eof reached */
     int write_flag;         /**< true if open for writing */

 #if FF_API_OLD_AVIO
     attribute_deprecated int is_streamed;
 #endif
     int max_packet_size;
     unsigned long checksum;
     unsigned char *checksum_ptr;
     unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);

     int error;              /**< contains the error code or 0 if no error happened */

     /**
      * Pause or resume playback for network streaming protocols - e.g. MMS.
      */

     int (*read_pause)(void *opaque, int pause);

     /**
      * Seek to a given timestamp in stream with the specified stream_index.
      * Needed for some network streaming protocols which don't support seeking
      * to byte position.
      */

     int64_t (*read_seek)(void *opaque, int stream_index,
                          int64_t timestamp, int flags);
     /**
      * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
      */
     int seekable;
 } AVIOContext;
 

 /* unbuffered I/O */
 

 #if FF_API_OLD_AVIO

 /**
  * URL Context.
  * New fields can be added to the end with minor version bumps.

  * Removal, reordering and changes to existing fields require a major

  * version bump.

  * sizeof(URLContext) must not be used outside libav*.

  * @deprecated This struct will be made private

  */

 typedef struct URLContext {

     const AVClass *av_class; ///< information for av_log(). Set by url_open().

     struct URLProtocol *prot;

     int flags;

     int is_streamed;  /**< true if streamed (no seek possible), default = false */
     int max_packet_size;  /**< if non zero, the stream is packetized with this max packet size */

     void *priv_data;

     char *filename; /**< specified URL */

     int is_connected;

 } URLContext;

 #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
 
 /**
  * @deprecated This struct is to be made private. Use the higher-level
  *             AVIOContext-based API instead.
  */
 typedef struct URLProtocol {
     const char *name;
     int (*url_open)(URLContext *h, const char *url, int flags);
     int (*url_read)(URLContext *h, unsigned char *buf, int size);
     int (*url_write)(URLContext *h, const unsigned char *buf, int size);
     int64_t (*url_seek)(URLContext *h, int64_t pos, int whence);
     int (*url_close)(URLContext *h);
     struct URLProtocol *next;
     int (*url_read_pause)(URLContext *h, int pause);
     int64_t (*url_read_seek)(URLContext *h, int stream_index,
                              int64_t timestamp, int flags);
     int (*url_get_file_handle)(URLContext *h);
     int priv_data_size;
     const AVClass *priv_data_class;
     int flags;

     int (*url_check)(URLContext *h, int mask);

 } URLProtocol;
 

 typedef struct URLPollEntry {
     URLContext *handle;
     int events;
     int revents;
 } URLPollEntry;
 

 /* not implemented */
 attribute_deprecated int url_poll(URLPollEntry *poll_table, int n, int timeout);
 

 /**

  * @name URL open modes

  * The flags argument to url_open and cosins must be one of the following
  * constants, optionally ORed with other flags.
  * @{
  */

 #define URL_RDONLY 1  /**< read-only */
 #define URL_WRONLY 2  /**< write-only */
 #define URL_RDWR   (URL_RDONLY|URL_WRONLY)  /**< read-write */

 /**
  * @}
  */
 
 /**
  * Use non-blocking mode.
  * If this flag is set, operations on the context will return
  * AVERROR(EAGAIN) if they can not be performed immediately.
  * If this flag is not set, operations on the context will never return
  * AVERROR(EAGAIN).
  * Note that this flag does not affect the opening/connecting of the
  * context. Connecting a protocol will always block if necessary (e.g. on
  * network protocols) but never hang (e.g. on busy devices).
  * Warning: non-blocking protocols is work-in-progress; this flag may be
  * silently ignored.
  */
 #define URL_FLAG_NONBLOCK 4

 typedef int URLInterruptCB(void);

 extern URLInterruptCB *url_interrupt_cb;

 /**

  * @defgroup old_url_funcs Old url_* functions

  * The following functions are deprecated. Use the buffered API based on #AVIOContext instead.

  * @{

  */

 attribute_deprecated int url_open_protocol (URLContext **puc, struct URLProtocol *up,
                                             const char *url, int flags);

 attribute_deprecated int url_alloc(URLContext **h, const char *url, int flags);

 attribute_deprecated int url_connect(URLContext *h);

 attribute_deprecated int url_open(URLContext **h, const char *url, int flags);

 attribute_deprecated int url_read(URLContext *h, unsigned char *buf, int size);

 attribute_deprecated int url_read_complete(URLContext *h, unsigned char *buf, int size);

 attribute_deprecated int url_write(URLContext *h, const unsigned char *buf, int size);

 attribute_deprecated int64_t url_seek(URLContext *h, int64_t pos, int whence);

 attribute_deprecated int url_close(URLContext *h);

 attribute_deprecated int64_t url_filesize(URLContext *h);

 attribute_deprecated int url_get_file_handle(URLContext *h);

 attribute_deprecated int url_get_max_packet_size(URLContext *h);

 attribute_deprecated void url_get_filename(URLContext *h, char *buf, int buf_size);

 attribute_deprecated int av_url_read_pause(URLContext *h, int pause);

 attribute_deprecated int64_t av_url_read_seek(URLContext *h, int stream_index,
                                               int64_t timestamp, int flags);

 attribute_deprecated void url_set_interrupt_cb(int (*interrupt_cb)(void));

 /**

  * returns the next registered protocol after the given protocol (the first if
  * NULL is given), or NULL if protocol is the last one.

  */

 URLProtocol *av_protocol_next(URLProtocol *p);
 

 /**

  * Register the URLProtocol protocol.

  *
  * @param size the size of the URLProtocol struct referenced

  */

 attribute_deprecated int av_register_protocol2(URLProtocol *protocol, int size);

 /**

  * @}
  */
 

 typedef attribute_deprecated AVIOContext ByteIOContext;
 

 attribute_deprecated int init_put_byte(AVIOContext *s,

                   unsigned char *buffer,
                   int buffer_size,
                   int write_flag,
                   void *opaque,

                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),

                   int64_t (*seek)(void *opaque, int64_t offset, int whence));

 attribute_deprecated AVIOContext *av_alloc_put_byte(
                   unsigned char *buffer,
                   int buffer_size,
                   int write_flag,
                   void *opaque,
                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                   int64_t (*seek)(void *opaque, int64_t offset, int whence));

 
 /**
  * @defgroup old_avio_funcs Old put_/get_*() functions

  * The following functions are deprecated. Use the "avio_"-prefixed functions instead.

  * @{
  */
 attribute_deprecated int          get_buffer(AVIOContext *s, unsigned char *buf, int size);

 attribute_deprecated int          get_partial_buffer(AVIOContext *s, unsigned char *buf, int size);

 attribute_deprecated int          get_byte(AVIOContext *s);
 attribute_deprecated unsigned int get_le16(AVIOContext *s);
 attribute_deprecated unsigned int get_le24(AVIOContext *s);
 attribute_deprecated unsigned int get_le32(AVIOContext *s);
 attribute_deprecated uint64_t     get_le64(AVIOContext *s);
 attribute_deprecated unsigned int get_be16(AVIOContext *s);
 attribute_deprecated unsigned int get_be24(AVIOContext *s);
 attribute_deprecated unsigned int get_be32(AVIOContext *s);
 attribute_deprecated uint64_t     get_be64(AVIOContext *s);

 
 attribute_deprecated void         put_byte(AVIOContext *s, int b);

 attribute_deprecated void         put_nbyte(AVIOContext *s, int b, int count);

 attribute_deprecated void         put_buffer(AVIOContext *s, const unsigned char *buf, int size);
 attribute_deprecated void         put_le64(AVIOContext *s, uint64_t val);
 attribute_deprecated void         put_be64(AVIOContext *s, uint64_t val);
 attribute_deprecated void         put_le32(AVIOContext *s, unsigned int val);
 attribute_deprecated void         put_be32(AVIOContext *s, unsigned int val);
 attribute_deprecated void         put_le24(AVIOContext *s, unsigned int val);
 attribute_deprecated void         put_be24(AVIOContext *s, unsigned int val);
 attribute_deprecated void         put_le16(AVIOContext *s, unsigned int val);
 attribute_deprecated void         put_be16(AVIOContext *s, unsigned int val);

 attribute_deprecated void         put_tag(AVIOContext *s, const char *tag);

 /**
  * @}
  */

 attribute_deprecated int     av_url_read_fpause(AVIOContext *h,    int pause);

 attribute_deprecated int64_t av_url_read_fseek (AVIOContext *h,    int stream_index,

                                                 int64_t timestamp, int flags);

 
 /**
  * @defgroup old_url_f_funcs Old url_f* functions

  * The following functions are deprecated, use the "avio_"-prefixed functions instead.

  * @{
  */
 attribute_deprecated int url_fopen( AVIOContext **s, const char *url, int flags);
 attribute_deprecated int url_fclose(AVIOContext *s);

 attribute_deprecated int64_t url_fseek(AVIOContext *s, int64_t offset, int whence);

 attribute_deprecated int url_fskip(AVIOContext *s, int64_t offset);

 attribute_deprecated int64_t url_ftell(AVIOContext *s);

 attribute_deprecated int64_t url_fsize(AVIOContext *s);

 #define URL_EOF (-1)
 attribute_deprecated int url_fgetc(AVIOContext *s);

 attribute_deprecated int url_setbufsize(AVIOContext *s, int buf_size);

 #ifdef __GNUC__
 attribute_deprecated int url_fprintf(AVIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
 #else
 attribute_deprecated int url_fprintf(AVIOContext *s, const char *fmt, ...);
 #endif

 attribute_deprecated void put_flush_packet(AVIOContext *s);

 attribute_deprecated int url_open_dyn_buf(AVIOContext **s);

 attribute_deprecated int url_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);

 attribute_deprecated int url_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);

 attribute_deprecated int url_fdopen(AVIOContext **s, URLContext *h);

 /**
  * @}
  */

 attribute_deprecated int url_ferror(AVIOContext *s);

 
 attribute_deprecated int udp_set_remote_url(URLContext *h, const char *uri);
 attribute_deprecated int udp_get_local_port(URLContext *h);

 
 attribute_deprecated void init_checksum(AVIOContext *s,
                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
                    unsigned long checksum);

 attribute_deprecated unsigned long get_checksum(AVIOContext *s);

 attribute_deprecated void put_strz(AVIOContext *s, const char *buf);
 /** @note unlike fgets, the EOL character is not returned and a whole
     line is parsed. return NULL if first char read was EOF */
 attribute_deprecated char *url_fgets(AVIOContext *s, char *buf, int buf_size);
 /**
  * @deprecated use avio_get_str instead
  */
 attribute_deprecated char *get_strz(AVIOContext *s, char *buf, int maxlen);
 /**
  * @deprecated Use AVIOContext.seekable field directly.
  */
 attribute_deprecated static inline int url_is_streamed(AVIOContext *s)
 {
     return !s->seekable;
 }
 attribute_deprecated URLContext *url_fileno(AVIOContext *s);
 
 /**
  * @deprecated use AVIOContext.max_packet_size directly.
  */
 attribute_deprecated int url_fget_max_packet_size(AVIOContext *s);
 
 attribute_deprecated int url_open_buf(AVIOContext **s, uint8_t *buf, int buf_size, int flags);
 
 /** return the written or read size */
 attribute_deprecated int url_close_buf(AVIOContext *s);
 
 /**
  * Return a non-zero value if the resource indicated by url
  * exists, 0 otherwise.

  * @deprecated Use avio_check instead.

  */

 attribute_deprecated int url_exist(const char *url);
 #endif // FF_API_OLD_AVIO

 
 /**

  * Return AVIO_FLAG_* access flags corresponding to the access permissions

  * of the resource in url, or a negative value corresponding to an
  * AVERROR code in case of failure. The returned access flags are
  * masked by the value in flags.
  *
  * @note This function is intrinsically unsafe, in the sense that the
  * checked resource may change its existence or permission status from
  * one call to another. Thus you should not trust the returned value,
  * unless you are sure that no other processes are accessing the
  * checked resource.
  */
 int avio_check(const char *url, int flags);

 
 /**
  * The callback is called in blocking functions to test regulary if
  * asynchronous interruption is needed. AVERROR_EXIT is returned
  * in this case by the interrupted function. 'NULL' means no interrupt
  * callback is given.
  */
 void avio_set_interrupt_cb(int (*interrupt_cb)(void));
 

 /**
  * Allocate and initialize an AVIOContext for buffered I/O. It must be later
  * freed with av_free().
  *
  * @param buffer Memory block for input/output operations via AVIOContext.

  *        The buffer must be allocated with av_malloc() and friends.

  * @param buffer_size The buffer size is very important for performance.
  *        For protocols with fixed blocksize it should be set to this blocksize.
  *        For others a typical size is a cache page, e.g. 4kb.
  * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
  * @param opaque An opaque pointer to user-specific data.
  * @param read_packet  A function for refilling the buffer, may be NULL.
  * @param write_packet A function for writing the buffer contents, may be NULL.
  * @param seek A function for seeking to specified byte position, may be NULL.
  *
  * @return Allocated AVIOContext or NULL on failure.
  */

 AVIOContext *avio_alloc_context(

                   unsigned char *buffer,
                   int buffer_size,
                   int write_flag,
                   void *opaque,

                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),

                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),

                   int64_t (*seek)(void *opaque, int64_t offset, int whence));

 void avio_w8(AVIOContext *s, int b);
 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
 void avio_wl64(AVIOContext *s, uint64_t val);
 void avio_wb64(AVIOContext *s, uint64_t val);
 void avio_wl32(AVIOContext *s, unsigned int val);
 void avio_wb32(AVIOContext *s, unsigned int val);
 void avio_wl24(AVIOContext *s, unsigned int val);
 void avio_wb24(AVIOContext *s, unsigned int val);
 void avio_wl16(AVIOContext *s, unsigned int val);
 void avio_wb16(AVIOContext *s, unsigned int val);

 /**
  * Write a NULL-terminated string.
  * @return number of bytes written.
  */

 int avio_put_str(AVIOContext *s, const char *str);

 /**

  * Convert an UTF-8 string to UTF-16LE and write it.
  * @return number of bytes written.
  */

 int avio_put_str16le(AVIOContext *s, const char *str);

 
 /**

  * Passing this as the "whence" parameter to a seek function causes it to
  * return the filesize without seeking anywhere. Supporting this is optional.
  * If it is not supported then the seek function will return <0.
  */
 #define AVSEEK_SIZE 0x10000
 
 /**
  * Oring this flag as into the "whence" parameter to a seek function causes it to
  * seek by any means (like reopening and linear reading) or other normally unreasonble
  * means that can be extreemly slow.
  * This may be ignored by the seek code.
  */
 #define AVSEEK_FORCE 0x20000
 
 /**

  * fseek() equivalent for AVIOContext.

  * @return new position or AVERROR.
  */

 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);

 
 /**

  * Skip given number of bytes forward
  * @return new position or AVERROR.
  */
 int64_t avio_skip(AVIOContext *s, int64_t offset);
 
 /**

  * ftell() equivalent for AVIOContext.

  * @return position or AVERROR.
  */

 static av_always_inline int64_t avio_tell(AVIOContext *s)
 {
     return avio_seek(s, 0, SEEK_CUR);
 }

 
 /**

  * Get the filesize.

  * @return filesize or AVERROR
  */

 int64_t avio_size(AVIOContext *s);

 
 /**

  * feof() equivalent for AVIOContext.

  * @return non zero if and only if end of file
  */

 int url_feof(AVIOContext *s);

 /** @warning currently size is limited */

 #ifdef __GNUC__

 int avio_printf(AVIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));

 #else

 int avio_printf(AVIOContext *s, const char *fmt, ...);

 #endif

 void avio_flush(AVIOContext *s);

 
 /**

  * Read size bytes from AVIOContext into buf.

  * @return number of bytes read or AVERROR

  */

 int avio_read(AVIOContext *s, unsigned char *buf, int size);

 /**

  * @name Functions for reading from AVIOContext

  * @{
  *
  * @note return 0 if EOF, so you cannot use it if EOF handling is
  *       necessary
  */

 int          avio_r8  (AVIOContext *s);
 unsigned int avio_rl16(AVIOContext *s);
 unsigned int avio_rl24(AVIOContext *s);
 unsigned int avio_rl32(AVIOContext *s);
 uint64_t     avio_rl64(AVIOContext *s);

 unsigned int avio_rb16(AVIOContext *s);
 unsigned int avio_rb24(AVIOContext *s);
 unsigned int avio_rb32(AVIOContext *s);
 uint64_t     avio_rb64(AVIOContext *s);
 /**
  * @}
  */

 /**

  * Read a string from pb into buf. The reading will terminate when either
  * a NULL character was encountered, maxlen bytes have been read, or nothing
  * more can be read from pb. The result is guaranteed to be NULL-terminated, it
  * will be truncated if buf is too small.
  * Note that the string is not interpreted or validated in any way, it
  * might get truncated in the middle of a sequence for multi-byte encodings.
  *
  * @return number of bytes read (is always <= maxlen).
  * If reading ends on EOF or error, the return value will be one more than
  * bytes actually read.
  */
 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
 
 /**

  * Read a UTF-16 string from pb and convert it to UTF-8.
  * The reading will terminate when either a null or invalid character was
  * encountered or maxlen bytes have been read.
  * @return number of bytes read (is always <= maxlen)
  */

 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);

 /**

  * @name URL open modes

  * The flags argument to avio_open must be one of the following
  * constants, optionally ORed with other flags.
  * @{
  */

 #define AVIO_FLAG_READ  1                                      /**< read-only */
 #define AVIO_FLAG_WRITE 2                                      /**< write-only */
 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE)  /**< read-write pseudo flag */

 /**
  * @}
  */
 
 /**
  * Use non-blocking mode.
  * If this flag is set, operations on the context will return
  * AVERROR(EAGAIN) if they can not be performed immediately.
  * If this flag is not set, operations on the context will never return
  * AVERROR(EAGAIN).
  * Note that this flag does not affect the opening/connecting of the
  * context. Connecting a protocol will always block if necessary (e.g. on
  * network protocols) but never hang (e.g. on busy devices).
  * Warning: non-blocking protocols is work-in-progress; this flag may be
  * silently ignored.
  */

 #define AVIO_FLAG_NONBLOCK 8

 
 /**

  * Create and initialize a AVIOContext for accessing the

  * resource indicated by url.
  * @note When the resource indicated by url has been opened in

  * read+write mode, the AVIOContext can be used only for writing.

  *

  * @param s Used to return the pointer to the created AVIOContext.

  * In case of failure the pointed to value is set to NULL.
  * @param flags flags which control how the resource indicated by url
  * is to be opened
  * @return 0 in case of success, a negative value corresponding to an
  * AVERROR code in case of failure
  */

 int avio_open(AVIOContext **s, const char *url, int flags);

 /**

  * Close the resource accessed by the AVIOContext s and free it.
  * This function can only be used if s was opened by avio_open().
  *
  * @return 0 on success, an AVERROR < 0 on error.

  */

 int avio_close(AVIOContext *s);

 /**

  * Open a write only memory stream.
  *
  * @param s new IO context
  * @return zero if no error.
  */

 int avio_open_dyn_buf(AVIOContext **s);

 /**

  * Return the written size and a pointer to the buffer. The buffer

  * must be freed with av_free().
  * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.

  *

  * @param s IO context

  * @param pbuffer pointer to a byte buffer

  * @return the length of the byte buffer
  */

 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);

 /**
  * Iterate through names of available protocols.

  * @note it is recommanded to use av_protocol_next() instead of this

  *
  * @param opaque A private pointer representing current protocol.
  *        It must be a pointer to NULL on first iteration and will
  *        be updated by successive calls to avio_enum_protocols.
  * @param output If set to 1, iterate over output protocols,
  *               otherwise over input protocols.
  *
  * @return A static string containing the name of current protocol or NULL
  */
 const char *avio_enum_protocols(void **opaque, int output);
 

 /**
  * Pause and resume playing - only meaningful if using a network streaming
  * protocol (e.g. MMS).
  * @param pause 1 for pause, 0 for resume
  */
 int     avio_pause(AVIOContext *h, int pause);
 
 /**
  * Seek to a given timestamp relative to some component stream.
  * Only meaningful if using a network streaming protocol (e.g. MMS.).
  * @param stream_index The stream index that the timestamp is relative to.
  *        If stream_index is (-1) the timestamp should be in AV_TIME_BASE
  *        units from the beginning of the presentation.
  *        If a stream_index >= 0 is used and the protocol does not support
  *        seeking based on component streams, the call will fail with ENOTSUP.
  * @param timestamp timestamp in AVStream.time_base units
  *        or if there is no stream specified then in AV_TIME_BASE units.
  * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
  *        and AVSEEK_FLAG_ANY. The protocol may silently ignore
  *        AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
  *        fail with ENOTSUP if used and not supported.
  * @return >= 0 on success
  * @see AVInputFormat::read_seek
  */
 int64_t avio_seek_time(AVIOContext *h, int stream_index,
                        int64_t timestamp, int flags);
 

 #endif /* AVFORMAT_AVIO_H */