def test_fft_nofft(self):
for _ in range(10):
x = th.randn(1024)
freq = random.uniform(0.01, 0.5)
y_fft = lowpass_filter(x, freq, fft=True)
y_ref = lowpass_filter(x, freq, fft=False)
self.assertSimilar(y_fft, y_ref, x, f"freq={freq}", tol=0.01)
def test_keep_or_kill(self):
for _ in range(10):
freq = random.uniform(0.01, 0.4)
sr = 1024
tone = pure_tone(freq * sr, sr=sr, dur=10)
# For this test we accept 5% tolerance, as 5% of delta in amplitude is -52dB.
tol = 5
zeros = 16
# If cutoff freauency is under freq, output should be zero
y_killed = lowpass_filter(tone, 0.9 * freq, zeros=zeros)
self.assertSimilar(y_killed,
0 * y_killed,
tone,
f"freq={freq}, kill",
tol=tol)
# If cutoff freauency is under freq, output should be input
y_pass = lowpass_filter(tone, 1.1 * freq, zeros=zeros)
self.assertSimilar(y_pass,
tone,
tone,
f"freq={freq}, pass",
tol=tol)
def apply_transform(
self,
samples: Tensor = None,
sample_rate: Optional[int] = None,
targets: Optional[Tensor] = None,
target_rate: Optional[int] = None,
) -> ObjectDict:
batch_size, num_channels, num_samples = samples.shape
cutoffs_as_fraction_of_sample_rate = (
self.transform_parameters["cutoff_freq"] / sample_rate
)
# TODO: Instead of using a for loop, perform batched compute to speed things up
for i in range(batch_size):
samples[i] = julius.lowpass_filter(
samples[i], cutoffs_as_fraction_of_sample_rate[i].item()
)
return ObjectDict(
samples=samples,
sample_rate=sample_rate,
targets=targets,
target_rate=target_rate,
)
def test_same_as_downsample(self):
for _ in range(10):
x = th.randn(2 * 3 * 4 * 100)
rolloff = 0.945
for old_sr in [2, 3, 4]:
y_resampled = resample_frac(x, old_sr, 1, rolloff=rolloff, zeros=16)
y_lowpass = lowpass_filter(x, rolloff / old_sr / 2, stride=old_sr, zeros=16)
self.assertSimilar(y_resampled, y_lowpass, x, f"old_sr={old_sr}")
def test(table, freq, zeros, fft=None, device="cpu"):
sr = 44_100
attns = []
for ratio in [0.9, 1, 1.1]:
x = pure_tone(ratio * freq * sr, sr, 4, device=device)
with Chrono() as chrono:
y = lowpass_filter(x, freq, fft=fft, zeros=zeros)
attns.append(format(volume(y) - volume(x), ".2f"))
table.line([freq] + attns + [int(1000 * chrono.duration)])
def apply_transform(self,
selected_samples: torch.Tensor,
sample_rate: int = None):
batch_size, num_channels, num_samples = selected_samples.shape
if sample_rate is None:
sample_rate = self.sample_rate
cutoffs_as_fraction_of_sample_rate = (
self.transform_parameters["cutoff_freq"] / sample_rate)
# TODO: Instead of using a for loop, perform batched compute to speed things up
for i in range(batch_size):
selected_samples[i] = julius.lowpass_filter(
selected_samples[i],
cutoffs_as_fraction_of_sample_rate[i].item())
return selected_samples
def test_constant(self):
x = th.ones(2048)
for zeros in [4, 10]:
for freq in [0.01, 0.1]:
y_low = lowpass_filter(x, freq, zeros=zeros)
self.assertLessEqual((y_low - 1).abs().mean(), 1e-6, (zeros, freq))
