comparison Syncopation models/KTH.py @ 1:b2da092dc2e0

The consolidated syncopation software. Have finished individual model and basic functions. Need to revise the coding in main.py, and add rhythm-input interface.

+'''
+Author: Chunyang Song
+Institution: Centre for Digital Music, Queen Mary University of London
+
+'''
+## Problems! Note indices, post bar
+
+from basic_functions import get_min_timeSpan, get_note_indices, repeat
+
+# To find the nearest power of 2 equal to or less than the given number
+def roundDownPower2(number):
+	i = 0
+	if number > 0:
+		while pow(2,i) > number or number >= pow(2,i+1):
+			i = i+1
+		power2 = pow(2,i)
+	else:
+		print 'Error: numbers that are less than 1 cannot be rounded down to its nearest power of two.'
+		power2 = None
+	return power2
+
+# To find the nearest power of 2 equal to or more than the given number
+def roundUpPower2(number):
+	i = 0
+	while pow(2,i) < number:
+		i = i + 1
+	return pow(2,i)
+
+# To examine whether start_time is 'off-beat'
+def start(start_time, c_n):
+	s = 0
+	if start_time % c_n != 0:
+		s = 2
+	return s
+
+# To examine whether end_time is 'off-beat'
+def end(end_time, c_n):
+	s = 0
+	if end_time % c_n != 0:
+		s = 1
+	return s
+
+# To calculate syncopation value of the sequence in the given time-signature.
+def get_syncopation(seq, timesig, postbar_seq):
+	syncopation = 0
+
+	numerator = int(timesig.split("/")[0])
+	if numerator == roundDownPower2(numerator):	# if is a binary time-signature
+		# converting to minimum time-span format
+		seq = get_min_timeSpan(seq)	
+		if postbar_seq != None:
+			postbar_seq = get_min_timeSpan(postbar_seq)
+
+		# sf is a stretching factor matching rhythm sequence and meter, as Keith defines the note duration as a multiple of 1/(2^d) beats where d is number of metrical level
+		sf = roundUpPower2(len(seq))
+		
+		# retrieve all the indices of all the notes in this sequence
+		note_indices = get_note_indices(seq)
+
+		for i in range(len(note_indices)):
+			# Assuming start_time is the index of this note, end_time is the index of the following note
+			start_time = note_indices[i]*sf/float(len(seq))
+
+			if i == len(note_indices)-1:	# if this is the last note, end_time is the index of the following note in the next bar
+				if postbar_seq != None and postbar_seq != repeat([0],len(postbar_seq)):
+					next_index = get_note_indices(postbar_seq)[0]+len(seq)
+					end_time = next_index*sf/float(len(seq))
+				else:	# or if the next bar is none or full rest, end_time is the end of this sequence.
+					end_time = sf
+			else:
+				end_time = note_indices[i+1]*sf/float(len(seq))
+
+			duration = end_time - start_time
+			c_n = roundDownPower2(duration)
+			syncopation = syncopation + start(start_time,c_n) + end(end_time,c_n)
+	else: 
+		print 'Error: KTH model can only deal with binary time-signature, e.g. 2/4 and 4/4. '
+		syncopation = None
+
+	return syncopation