[farshizzo]

If you need exactly 1800 samples, then setup a counter that will stop the timer after the specified number of samples have been recorded. Here is some sample code that should show you how it works:

import viz
viz.go()

MAX_SAMPLES = 1800
SAMPLE_RATE = 1.0 / 30.0

samples = 0
def onTimer(num):
	global samples
	if num == 1:
		
		#TODO: Process sample
		
		#Increment samples
		samples += 1
		if samples < MAX_SAMPLES:
			viz.starttimer(1,SAMPLE_RATE)
		else:
			print 'Finished collecting samples'
			
viz.callback(viz.TIMER_EVENT,onTimer)


def onKeyDown(key):
	global samples
	if key == ' ':
		#Clear samples and start timer
		samples = 0
		viz.starttimer(1,SAMPLE_RATE)

viz.callback(viz.KEYDOWN_EVENT,onKeyDown)