FFmpeg源码学习(一)：avformat_open_input源码分析

/**
* Open an input stream and read the header. The codecs are not opened.
* The stream must be closed with avformat_close_input().
*
* &＃64;param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
* May be a pointer to NULL, in which case an AVFormatContext is allocated by this
* function and written into ps.
* Note that a user-supplied AVFormatContext will be freed on failure.
* &＃64;param url URL of the stream to open.
* &＃64;param fmt If non-NULL, this parameter forces a specific input format.
* Otherwise the format is autodetected.
* &＃64;param options A dictionary filled with AVFormatContext and demuxer-private options.
* On return this parameter will be destroyed and replaced with a dict containing
* options that were not found. May be NULL.
*
* &＃64;return 0 on success, a negative AVERROR on failure.
*
* &＃64;note If you want to use custom IO, preallocate the format context and set its pb field.
*/

int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options)

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;

URLProtocol ff_pipe_protocol &＃61; {.name &＃61; "pipe",.url_open &＃61; pipe_open,.url_read &＃61; file_read,.url_write &＃61; file_write,.url_get_file_handle &＃61; file_get_handle,.url_check &＃61; file_check,
};

URLProtocol ff_rtmp_protocol &＃61; {.name &＃61; "rtmp",.url_open &＃61; rtmp_open,.url_read &＃61; rtmp_read,.url_write &＃61; rtmp_write,.url_close &＃61; rtmp_close,.url_read_pause &＃61; rtmp_read_pause,.url_read_seek &＃61; rtmp_read_seek,.url_get_file_handle &＃61; rtmp_get_file_handle,.priv_data_size &＃61; sizeof(RTMP),.flags &＃61; URL_PROTOCOL_FLAG_NETWORK,
};