Variables :
X - x axis
Y - y axis
I - Use to draw a line
v - Kinda hard to describe for me... sorta value of music (Think Simple/Oscillioscope)
w - Width of AVS screen (in pixels)
H - Height of AVS screen (in pixels)
You might want to learn the other commands, too - All the commands (sin, cos, tan, etc) from Dynamic Movement can be used for SSC...
I also believe there's numerous other topics questioning about SSC... shouldn't you read those first? (Besides, I'm not a SSC type of a guy =p )