1. connect strings
fname = strcat('C:\Users\user_name\work\video\',avi_name{1});
2. seperate pathstr, name and ext
[pathstr, name, ext] = fileparts(filename) returns the path name, file name, and extension for the specified file. The file does not have to exist. filename is a string enclosed in single quotes. The returned ext field contains a dot (.) before the file
extension.