Challenge with id3tag_set_albumart of LAME

    FILE* fpi = 0;  //Initial file structure set to zero.
    char *albumart = 0; //Initial char pointer set to zero.
    char *filename = "ty.jpg";//Initial file name set to "ty.jpg".
    size_t size;//Initial size variable not initialized, of _W64 unsigned int type on 
                // my system, yours may be a _W32 unsigned int type.
  
//Here, I presume, you're opening the JPG in READ | BINARY mode. 
    fpi = fopen(filename, "rb");
    fopen(&fpi, filename, "rb, IMG= encoding "); //This is how it is done correctly.
/*
"r"   Opens for reading. If the file does not exist or cannot be found, the fopen call fails.
"b"   Open in binary (untranslated) mode; translations involving carriage-return and linefeed characters are suppressed. 

Here you 'seek' the file, for what don't know as you didn't indicate it. 
How it is defined: int fseek(FILE *stream, long offset, int origin );

    Look at the file from end, if there is a return value it is unknown.
*/
    fseek(fpi, 0, SEEK_END);// not doing anything for you
// Here, I presume, that having possibly opened the file, you try to get the size of it.
    size = ftell(fpi);// However since you opened it in binary mode, it may not work with _W64 unsigned int type. ftell  and _ftelli64 return the current file position. The value returned by ftell and _ftelli64 may not reflect the physical byte offset for streams opened in text mode, because text mode causes carriage return–linefeed translation. Use ftell with fseek or _ftelli64 with _fseeki64 to return to file locations correctly. On error, ftell and _ftelli64 invoke the invalid parameter handler, as described in Parameter Validation.     

//Since you're at the end of the file and moved 0Bytes using fseek, ftell tells you are at EOF 
      // Move the pointer by reading data: 
      fread( list, sizeof( char ), 100, stream );
      // Get position after read: 
      position = ftell( stream );
      printf( "Position after trying to read 100 bytes: %ld\n",
              position );
// Your position is EOF, 
/*
SEEK_SET = Beginning of file.

You can use fseek and _fseeki64 to reposition the pointer anywhere in a file. The pointer can also be positioned beyond the end of the file. fseek and _fseeki64clears the end-of-file indicator and negates the effect of any prior ungetc calls against stream.

When a file is opened for appending data, the current file position is determined by the last I/O operation, not by where the next write would occur. If no I/O operation has yet occurred on a file opened for appending, the file position is the start of the file. 

For streams opened in text mode, fseek and _fseeki64have limited use, because carriage return–line feed translations can cause fseek and _fseeki64to produce unexpected results. 

The only fseek and _fseeki64 operations guaranteed to work on streams opened in text mode are: 
•Seeking with an offset of 0 relative to any of the origin values.
•Seeking from the beginning of the file with an offset value returned from a call to ftell when using fseek.

     This says to move to start the file and move 0 units of measure.
     fseek(fpi, 0, SEEK_SET); //    
     albumart = (char*)malloc(size);// doesn't work because size = 0
     size = fseek(fpi, SEEK_END, SEEK_SET); //This might have worked better.

However:
*/
//   albumart = (char*)malloc(size); fread(albumart, 1, size, fpi); This is better as:
//  size_t fread( void *buffer, size_t size, size_t count, FILE *stream ); // Read the file


    size = fread(albumart,(char),sizeof(fpi),fpi);// This reads the file and gives you the correct size and stores the data in albumart. 

    id3tag_set_albumart(lame, albumart, size); // So now if you did the above statement then this might work.
    free(albumart);
    fclose(fpi);