/* FOURCC reader and changer, v0.1 by Julien Antille */
/* julien.antille@xxxxxxxxx */



#include <stdio.h>

int display_fourcc(char * filename) {

      char FOURCC[5];
      FILE * fichier;

      if((fichier = fopen(filename, "r")) == NULL){

      	printf("Cannot open %s\n", filename);
        return 0;
      }

      //0xBC is the offset of the FOURCC's 1st byte
      fseek(fichier, 0xBC, 0);

      if ((fgets(FOURCC, 5, fichier)==NULL)) {
         printf("File does not seem to be a valid AVI\n"); return 0;
      }

      printf("FOURCC for %s is %s\n", filename, FOURCC);
      fclose(fichier);

}

int change_fourcc(char * filename, char * fourcc){

     FILE * fichier;

     if (strlen(fourcc) != 4) {
     	printf("FOURCC length must be 4 bytes\n"); return 0;
     }

     if((fichier = fopen(filename, "r+")) == NULL){

      	printf("Cannot open %s for read-write\n", filename);
        return 0;
     }
     
      //0xBC is the offset of the FOURCC's 1st byte
      fseek(fichier, 0xBC, 0);

      if((fputs(fourcc, fichier) == -1)) {
      	printf("Failed to change FOURCC !\n");
	return 0;
      }


      printf("FOURCC changed to %s\n", fourcc);
      fclose(fichier);
      return 1;

}

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

      if (!argv[1]) {
      	printf("Usage : fourcc <filename.avi> [forced_fourcc]\n");
        printf("The usage of forced_fourcc forces the FOURCC for the given AVI. Use with caution\n");
        return 0;
      }

      if (!argv[2]){
      	return display_fourcc(argv[1]);
      }
      else {
	return change_fourcc(argv[1], argv[2]);
      }

}