def linear_envelope(start_amp, end_amp, width):
''' Generate an envelope, which spans some line.
Args:
start_amp - starting amplitude of envelope
end_amp - ending amplitude of envelope
width - floating point #/chunks wide that the envelope is
Yields:
A numpy array representing a linear envelope.
'''
#FIXME: width should be a note duration, not a multiple of chunk size
#FIXME: need a way to end attack early to start release, for short notes
chunk_size = oscil.get_chunk_size()
last_amp = start_amp
slope = (end_amp - start_amp) / width
for pos in it.count(chunk_size, chunk_size):
amp = slope * pos
samples = np.linspace(last_amp, amp, chunk_size, False)
if pos > width:
overlap = slice(width - pos, None)
samples[overlap] = 1
yield samples
raise StopIteration
yield samples
last_amp = amp
def multiply(*args, **kwargs):
'''Produces a wave that is the product of all supplied waves.
Args:
*args - see _do_op()
**kwargs - see _do_op()
Returns:
Wave chunk yielded by _do_op() operation.
'''
fill = np.ones(oscil.get_chunk_size())
return _do_op(functools.partial(np.prod, axis=0), "multiply", fill, *args, **kwargs)
def add(*args, **kwargs):
'''Produces a wave that is the sum of all supplied waves.
Args:
*args - see _do_op()
**kwargs - see _do_op()
Returns:
Wave chunk yielded by _do_op() operation.
'''
fill = np.zeros(oscil.get_chunk_size())
return _do_op(functools.partial(np.sum, axis=0), "add", fill, *args, **kwargs)
def filter(wave, taps):
'''This FIR filter *appproximation* is of too poor quality to be of use. '''
highpass = 0
if taps < 0:
taps = -taps
highpass = 1
buff = np.zeros(taps)
num_samples = oscil.get_chunk_size()
moving_averages = np.zeros(num_samples)
i = j = 0
for chunk in wave:
moving_averages = np.convolve(chunk, np.ones((taps,))/taps)[(taps-1):]
# apply "filter"
if (highpass):
chunk -= moving_averages
else:
chunk = moving_averages
yield chunk
def echo(timer, wave, vol, delay):
'''Apply an echo to a wave.
Args:
timer - used to calculate the delay
wave - numpy array of base wave, which will be echoed
vol - volume of echo [0,1]
the volume of the wave will be reduced to (1 - vol)
delay - delay of echo, in units of whole note duration
Yields:
Numpy array of original wave with echo applied.
'''
limits.validate.vol(vol)
width = timer.samples_per_note(1) * delay
chunk_size = oscil.get_chunk_size()
num_chunks = ceil(width / chunk_size)
buff = deque([np.zeros(chunk_size) for _ in range(num_chunks)])
for chunk in wave:
buff.append(chunk)
yield chunk*(1-vol) + buff.popleft()*vol
