int read_samples(double *buffer, int64_t len);
int write_samples(double **buffer, int64_t len);
int get_index(IndexFile *index_file, MainProgressBar *progress_bar);
int read_samples(double *buffer, int64_t len);
int write_samples(double **buffer, int64_t len);
int get_index(IndexFile *index_file, MainProgressBar *progress_bar);