>>Is there anyone who can tell me how can I know there is a QT Musical 
>Instruments or not?
>
>TIA.

You might find that MIDI & Musical Instruments are all "Components".  The 
Component Manager is not directly available in FB, you will need to 
convert the header files.  You will also need an understanding of 
Component Groups & Types - which is all explained in Inside Mac.

I found the following related "Components" installed on my machine:

sgpn	musi	thng	Instrument	
Configure Music capture channel

sgch	musi	appl	Music	
Captures MIDI into QuickTime movies	

tune	tune	appl	Tune Player	
Plays musical sequences.	

mhlr	musi	appl	Apple Music Media Handler	
Plays QuickTime music	

musi	gene	appl	Generic MIDI Music Player	
Customizable MIDI Music Device.	

musi	gm  	appl	General MIDI Music Player	
Plays music on any General MIDI synthesizer.	

musi	ss  	appl	Software Music Player	
Plays musical notes on the Macintosh.
	
nota	nota	appl	Note Allocator	
Allocates music-playing resources.