raw2rsf: convert raw sound file (PCM, 8-bit, 8000 samples per second) to LEGO EV3 Sound file (.rsf)

raw2rsf.c

/* See more details at https://tiebing.blogspot.com/2019/09/lego-ev3-sound-file-rsf-format.html */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int argc, char **argv){
        int i;
        int count;
        char buf[1024];
        if (argc!=2){
                printf("\n Usage: %s <input-raw-audio-file>\n", argv[0]);
                return -1;
        }
        char *infile=argv[1];
        int fd=open(infile,O_RDONLY);
        if (fd<0){
                perror("open error\n");
                return -1;
        }
        off_t fsize=lseek(fd,0,SEEK_END);
        if (fsize<0){
                perror("lseek error\n");
                return -1;
        }

        if (fsize>65535){
                fprintf(stderr,"Error: input file large than 65535 bytes\n");
                return -1;
        }
        lseek(fd,0,SEEK_SET);

        buf[0]=0x01;
        buf[1]=0x00;
        buf[2]=fsize/256;
        buf[3]=fsize%256;
        buf[4]=0x1f;
        buf[5]=0x40;
        buf[6]=0x00;
        buf[7]=0x00;
        write(1,buf,8);

        while((count=read(fd,buf,sizeof(buf)))>0){
                write(1,buf,count);
        }

        close(fd);

        return 0;
}