csong@1: '''
csong@1: Author: Chunyang Song
csong@1: Institution: Centre for Digital Music, Queen Mary University of London
csong@1: 
csong@1: '''
csong@1: 
csong@32: from basic_functions import get_note_indices, repeat, velocity_sequence_to_min_timespan
csong@1: 
csong@1: # To find the nearest power of 2 equal to or less than the given number
csong@20: def round_down_power_2(number):
csong@1: 	i = 0
csong@1: 	if number > 0:
csong@1: 		while pow(2,i) > number or number >= pow(2,i+1):
csong@1: 			i = i+1
csong@1: 		power2 = pow(2,i)
csong@1: 	else:
csong@1: 		print 'Error: numbers that are less than 1 cannot be rounded down to its nearest power of two.'
csong@1: 		power2 = None
csong@1: 	return power2
csong@1: 
csong@1: # To find the nearest power of 2 equal to or more than the given number
csong@20: def round_up_power_2(number):
csong@1: 	i = 0
csong@1: 	while pow(2,i) < number:
csong@1: 		i = i + 1
csong@1: 	return pow(2,i)
csong@1: 
csong@1: # To examine whether start_time is 'off-beat'
csong@22: def start_time_offbeat_measure(startTime, c_n):
csong@22: 	measure = 0
csong@20: 	if startTime % c_n != 0:
csong@22: 		measure = 2
csong@22: 	return measure
csong@1: 
csong@1: # To examine whether end_time is 'off-beat'
csong@22: def end_time_offbeat_measure(endTime, c_n):
csong@22: 	measure = 0
csong@20: 	if endTime % c_n != 0:
csong@22: 		measure = 1
csong@22: 	return measure
csong@1: 
csong@22: def get_syncopation(bar, parameters = None):
csong@21: 	syncopation = None
csong@1: 
csong@21: 	# KTH only deals with simple-duple meter where the number of beats per bar is a power of two.
csong@21: 	numerator = bar.get_time_signature().get_numerator()
csong@21: 	if numerator != round_down_power_2(numerator):
csong@21: 		print 'Warning: KTH model detects non simple-duple meter so returning None.'
csong@21: 	else:
csong@21: 		# retrieve note-sequence and next bar's note-sequence
csong@21: 		noteSequence = bar.get_note_sequence()
csong@23: 		#for note in noteSequence:
csong@23: 		#	print note.to_string()
csong@23: 		#print 'barlength',bar.get_bar_ticks()
csong@23: 
csong@21: 		nextbarNoteSequence = None
csong@21: 		if bar.get_next_bar() != None:
csong@21: 			nextbarNoteSequence = bar.get_next_bar().get_note_sequence()
csong@1: 
csong@22: 		# convert note sequence to its minimum time-span representation so that the later calculation can be faster
csong@23: 		# noteSequence = note_sequence_to_min_timespan(noteSequence)
csong@23: 		# find delta_t 
csong@23: 		Tmin = len(velocity_sequence_to_min_timespan(bar.get_velocity_sequence()))
csong@23: 		#print 'Tmin',Tmin
csong@23: 		T = round_up_power_2(Tmin)
csong@23: 		#print 'T',T
csong@23: 		deltaT = float(bar.get_bar_ticks())/T
csong@23: 		#print 'delta',deltaT
csong@23: 
csong@22: 
csong@22: 		# calculate syncopation note by note
csong@22: 		syncopation = 0
csong@22: 
csong@22: 		for note in noteSequence:
csong@23: 			c_n = round_down_power_2(note.duration/deltaT)
csong@23: 			#print 'd', note.duration
csong@23: 			#print 'c_n', c_n
csong@23: 			endTime = note.startTime + note.duration
csong@23: 			#print float(note.startTime)/deltaT, float(endTime)/deltaT
csong@23: 			syncopation = syncopation + start_time_offbeat_measure(float(note.startTime)/deltaT,c_n) + end_time_offbeat_measure(float(endTime)/deltaT,c_n)
csong@22: 
csong@21: 
csong@23: 	return syncopation
csong@21: 
csong@21: # # To calculate syncopation value of the sequence in the given time-signature.
csong@21: # def get_syncopation(seq, timesig, postbar_seq):
csong@21: # 	syncopation = 0
csong@21: 
csong@21: # 	numerator = int(timesig.split("/")[0])
csong@21: # 	if numerator == round_down_power_2(numerator):	# if is a binary time-signature
csong@21: # 		# converting to minimum time-span format
csong@21: # 		seq = get_min_timeSpan(seq)	
csong@21: # 		if postbar_seq != None:
csong@21: # 			postbar_seq = get_min_timeSpan(postbar_seq)
csong@21: 
csong@21: # 		# 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
csong@21: # 		sf = round_up_power_2(len(seq))
csong@1: 		
csong@21: # 		# retrieve all the indices of all the notes in this sequence
csong@21: # 		note_indices = get_note_indices(seq)
csong@1: 
csong@21: # 		for i in range(len(note_indices)):
csong@21: # 			# Assuming start_time is the index of this note, end_time is the index of the following note
csong@21: # 			start_time = note_indices[i]*sf/float(len(seq))
csong@1: 
csong@21: # 			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
csong@21: # 				if postbar_seq != None and postbar_seq != repeat([0],len(postbar_seq)):
csong@21: # 					next_index = get_note_indices(postbar_seq)[0]+len(seq)
csong@21: # 					end_time = next_index*sf/float(len(seq))
csong@21: # 				else:	# or if the next bar is none or full rest, end_time is the end of this sequence.
csong@21: # 					end_time = sf
csong@21: # 			else:
csong@21: # 				end_time = note_indices[i+1]*sf/float(len(seq))
csong@1: 
csong@21: # 			duration = end_time - start_time
csong@21: # 			c_n = round_down_power_2(duration)
csong@21: # 			syncopation = syncopation + start(start_time,c_n) + end(end_time,c_n)
csong@21: # 	else: 
csong@21: # 		print 'Error: KTH model can only deal with binary time-signature, e.g. 2/4 and 4/4. '
csong@21: # 		syncopation = None
csong@1: 
csong@21: # 	return syncopation