Defined in avformat.h

typedef struct AVInputFormat {
    const char *name;
    const char *long_name;
    /** size of private data so that it can be allocated in the wrapper */
    int priv_data_size;
    /** tell if a given file has a chance of being parsed by this format */
    int (*read_probe)(AVProbeData *);
    /** read the format header and initialize the AVFormatContext
       structure. Return 0 if OK. 'ap' if non NULL contains
       additional paramters. Only used in raw format right
       now. 'av_new_stream' should be called to create new streams.  */
    int (*read_header)(struct AVFormatContext *,
                       AVFormatParameters *ap);
    /** read one packet and put it in 'pkt'. pts and flags are also
       set. 'av_new_stream' can be called only if the flag
       AVFMTCTX_NOHEADER is used. */
    int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
    /** close the stream. The AVFormatContext and AVStreams are not
       freed by this function */
    int (*read_close)(struct AVFormatContext *);
    /**
     * seek to a given timestamp relative to the frames in
     * stream component stream_index
     * @param stream_index must not be -1
     * @param flags selects which direction should be preferred if no exact
     *              match is available
     */
    int (*read_seek)(struct AVFormatContext *,
                     int stream_index, int64_t timestamp, int flags);
    /**
     * gets the next timestamp in AV_TIME_BASE units.
     */
    int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
                              int64_t *pos, int64_t pos_limit);
    /** can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER */
    int flags;
    /** if extensions are defined, then no probe is done. You should
       usually not use extension format guessing because it is not
       reliable enough */
    const char *extensions;
    /** general purpose read only value that the format can use */
    int value;
 
    /** start/resume playing - only meaningful if using a network based format
       (RTSP) */
    int (*read_play)(struct AVFormatContext *);
 
    /** pause playing - only meaningful if using a network based format
       (RTSP) */
    int (*read_pause)(struct AVFormatContext *);
 
    const struct AVCodecTag **codec_tag;
 
    /* private fields */
    struct AVInputFormat *next;
} AVInputFormat;