linux里helloworld

 gcc -fpermissive sp.c   -I ../ff4.3.1 -L ./lib  -lavdevice -lavfilter -lavformat -lavcodec -lswresample -lswscale -lavutil -lm -lpthread -lz -llzma

#include <inttypes.h>
#include <math.h>
#include <limits.h>
#include <signal.h>
#include <stdint.h>


#include "libavformat/avformat.h"
#include "libavdevice/avdevice.h"






int main(int argc, char **argv)
{




    /* register all codecs, demux and protocols */
#if CONFIG_AVDEVICE
    avdevice_register_all();
#endif
    avformat_network_init();



    /* never returns */

    return 0;
}