write_file.c

#include <stdio.h>
#include <libavutil/log.h>
#include <libavformat/avio.h>


int main(int argc, char *argv[])
{
    int err_code;

    char *src_filename = NULL;
    AVIOContext *avio_ctx = NULL;

    unsigned char buf[] = "hello world!";

    av_log_set_level(AV_LOG_DEBUG);

    if(argc < 2){
        av_log(NULL, AV_LOG_DEBUG, "The count of pamameter should be more than two!\n");
        exit(1);
    }

    src_filename = argv[1];
    if(!src_filename){
        av_log(NULL, AV_LOG_DEBUG, "Invalid src filename\n");
        exit(1);
    }

    if((err_code=avio_open(&avio_ctx, src_filename, AVIO_FLAG_WRITE)) < 0){
        av_log(NULL, AV_LOG_DEBUG, "Could not open file %s\n", src_filename);
        exit(1);
    }

    avio_write(avio_ctx, buf, 12);

    avio_close(avio_ctx);

    return 0;
}