I'm using mciSendString and I was wondering how do you retrieve the file name from the alias.

Given the following code:
mciSendString("open music.mp3 type mpegvideo alias myfile", NULL, 0, 0); 	
mciSendString("play myfile repeat", NULL, 0, 0);
What is the command, if there is one, that I can use to return a string of music.mp3 from the alias. I would like to know because I'm creating a program that plays music amongst 5 different alias'. During the program, events happen that would cause another music file to open. I would like to be able to check if the one of the alias' happen to be one of the music files already playing. This way I don't play the same file at the same time.