def spectrogram(samples, sample_rate, frame_len, fps, batch=50):
"""
Computes a magnitude spectrogram for a given vector of samples at a given
sample rate (in Hz), frame length (in samples) and frame rate (in Hz).
Allows to transform multiple frames at once for improved performance (with
a default value of 50, more is not always better). Returns a numpy array.
"""
if len(samples) < frame_len:
return np.empty((0, frame_len // 2 + 1), dtype=samples.dtype)
win = np.hanning(frame_len)
hopsize = sample_rate // fps
num_frames = max(0, (len(samples) - frame_len) // hopsize + 1)
batch = min(batch, num_frames)
if batch <= 1 or not samples.flags.c_contiguous:
rfft = rfft_builder(samples[:frame_len], n=frame_len)
spect = np.vstack(np.abs(rfft(samples[pos:pos + frame_len] * win))
for pos in range(0, len(samples) - frame_len + 1,
int(hopsize)))
else:
rfft = rfft_builder(np.empty((batch, frame_len), samples.dtype),
n=frame_len, threads=1)
frames = np.lib.stride_tricks.as_strided(
samples, shape=(num_frames, frame_len),
strides=(samples.strides[0] * hopsize, samples.strides[0]))
spect = [np.abs(rfft(frames[pos:pos + batch] * win))
for pos in range(0, num_frames - batch + 1, batch)]
if num_frames % batch:
spect.extend(spectrogram(
samples[(num_frames // batch * batch) * hopsize:],
sample_rate, frame_len, fps, batch=1))
spect = np.vstack(spect)
return spect
def spectrogram_plans(frame_len, batch=48, dtype=np.float32):
"""
Precompute plans for spectrogram(), for a given frame length, batch size
and dtype. Returns two plans (single spectrum and batch), and a window.
"""
input_array = empty_aligned((batch, frame_len), dtype=dtype)
win = np.hanning(frame_len).astype(dtype)
return (rfft_builder(input_array[0]), rfft_builder(input_array), win)
def __new__(cls, frames, window=np.hanning, fft_size=None,
circular_shift=False, include_nyquist=False, fft_window=None,
fftw=None, **kwargs):
# pylint: disable=unused-argument
if isinstance(frames, ShortTimeFourierTransform):
# already a STFT, use the frames thereof
frames = frames.frames
# instantiate a FramedSignal if needed
if not isinstance(frames, FramedSignal):
frames = FramedSignal(frames, **kwargs)
# size of the frames
frame_size = frames.shape[1]
if fft_window is None:
# if a callable window function is given, use the frame size to
# create a window of this size
if hasattr(window, '__call__'):
window = window(frame_size)
# window used for FFT
try:
# if the signal is not scaled, scale the window accordingly
max_range = float(np.iinfo(frames.signal.dtype).max)
try:
# scale the window by the max_range
fft_window = window / max_range
except TypeError:
# if the window is None we can't scale it, thus create a
# uniform window and scale it accordingly
fft_window = np.ones(frame_size) / max_range
except ValueError:
# no scaling needed, use the window as is (can also be None)
fft_window = window
# use FFTW to speed up STFT
try:
# Note: use fft_window instead of a frame because it has already
# the correct dtype (frames are multiplied with this window)
fftw = rfft_builder(fft_window, fft_size, axis=0)
except AttributeError:
pass
# calculate the STFT
data = stft(frames, fft_window, fft_size=fft_size,
circular_shift=circular_shift,
include_nyquist=include_nyquist, fftw=fftw)
# cast as ShortTimeFourierTransform
obj = np.asarray(data).view(cls)
# save the other parameters
obj.frames = frames
obj.window = window
obj.fft_window = fft_window
obj.fft_size = fft_size if fft_size else frame_size
obj.circular_shift = circular_shift
obj.include_nyquist = include_nyquist
# return the object
return obj
def filtered_stft(samples, frame_len, hop_size, filterbank):
"""
Computes an STFT, applying a filterbank on the way to minimize memory use.
"""
window = np.hanning(frame_len)
rfft = rfft_builder(samples[:frame_len], n=frame_len)
spect = np.vstack(
np.dot(
np.abs(rfft(samples[pos:pos + frame_len] *
window))[:len(filterbank)], filterbank)
for pos in range(0,
len(samples) - frame_len + 1, hop_size))
return spect
def spectrogram_partial(samples,
sample_rate,
frame_len,
fps,
save_input,
dump_path,
batch=50):
"""
Computes a magnitude spectrogram for a given vector of samples at a given
sample rate (in Hz), frame length (in samples) and frame rate (in Hz).
Allows to transform multiple frames at once for improved performance (with
a default value of 50, more is not always better). Returns a numpy array.
"""
if len(samples) < frame_len:
return np.empty((0, frame_len // 2 + 1), dtype=samples.dtype)
win = np.hanning(frame_len)
hopsize = sample_rate // fps
num_frames = max(0, (len(samples) - frame_len) // hopsize + 1)
batch = min(batch, num_frames)
if batch <= 1 or not samples.flags.c_contiguous:
rfft = rfft_builder(samples[:frame_len], n=frame_len)
spect = np.vstack(
(rfft(samples[pos:pos + frame_len] * win))
for pos in range(0,
len(samples) - frame_len + 1, int(hopsize)))
else:
rfft = rfft_builder(np.empty((batch, frame_len), samples.dtype),
n=frame_len,
threads=1)
frames = np.lib.stride_tricks.as_strided(
samples,
shape=(num_frames, frame_len),
strides=(samples.strides[0] * hopsize, samples.strides[0]))
spect = [(rfft(frames[pos:pos + batch] * win))
for pos in range(0, num_frames - batch + 1, batch)]
if num_frames % batch:
spect.extend(
spectrogram(samples[(num_frames // batch * batch) * hopsize:],
sample_rate,
frame_len,
fps,
batch=1))
spect = np.vstack(spect)
if save_input:
# extract magnitude and phase from the input audio.
# returns magnitude and phase arrays in polar form. so, spect = magnitudes * phases. to find phase just use np.exp(np.angle(D) * j * 1)
magnitudes, phases = librosa.core.magphase(spect.T)
'''spect_recon = magnitudes * phases # * is element-wise multiplication
# inverting
win_len = frame_len
ifft_window = np.hanning(win_len)
n_frames = spect_recon.shape[1]
expected_signal_len = frame_len + hopsize * (n_frames - 1) # How? but important
audio_recon = np.zeros(expected_signal_len)
for i in range(n_frames):
sample = i * hopsize
spec = spect_recon[:, i].flatten()
spec = np.concatenate((spec.conj(), spec[-2:0:-1]), 0) # not clear? but expands the 513 input to 1024 as DFT is symmetric
ytmp = ifft_window * np.fft.irfft(spec, n = frame_len)
audio_recon[sample:(sample + frame_len)] = audio_recon[sample:(sample + frame_len)] + ytmp
librosa.output.write_wav(os.path.join(dump_path, 'input_audio_recon.wav'), audio_recon, sample_rate)'''
# saving all the phase information to be used while reconstructing from saliency maps.
# phases.shape: (d, t)
np.savez(os.path.join(dump_path, 'amp'), **{'amp': magnitudes.T})
np.savez(os.path.join(dump_path, 'phases'), **{'phases': phases.T})
# done this as due to the previous code datatype mismatch happens while returning from function call.
spect = magnitudes.T
# comes here two times.
return spect
