def test_zero_d0(self):
'''Test dither function for a positive d0'''
quantize = Mock(step=12)
emb = BinaryDM(quantize, d0=0)
self.assertEqual(emb.dither(0), 0)
self.assertEqual(emb.dither(1), -6)
def test_with_tolerable_noise(self):
def add_noise(x, step):
'''
Add tolerable noise. Return noisy signal
Arguments
x -- amplitude of signal
step -- quantization step
'''
noise = random.random() * step / 4
return x + random.choice([-1, 1]) * noise
step = 6
d0 = random.uniform(-3, 3)
x = random.random() * 100
quantizer = UniformQuantizer(step)
emb = BinaryDM(quantizer, d0)
# embed a zero
sm = emb.embed(x, 0)
y = add_noise(sm, step)
self.assertEqual(emb.extract(y), 0)
# embed a one
sm = emb.embed(x, 1)
y = add_noise(sm, step)
self.assertEqual(emb.extract(y), 1)
def test_without_noise(self):
step = 12
d0 = random.uniform(-6, 6)
x = random.random() * 100
quantizer = UniformQuantizer(step)
emb = BinaryDM(quantizer, d0)
# embed a zero
self.assertEqual(emb.extract(emb.embed(x, 0)), 0)
# embed a one
self.assertEqual(emb.extract(emb.embed(x, 1)), 1)
def test_zero_embedded(self):
quantizer = MagicMock()
emb = BinaryDM(quantizer, d0=5)
# emb.embed(x, 0) => 12
# emb.embed(x, 1) => 5
emb.embed = Mock(side_effect=[12, 5])
self.assertEqual(emb.extract(10), 0)
self.assertListEqual(emb.embed.call_args_list,
[call(10, 0), call(10, 1)])
# Equal distance
emb.embed = Mock(side_effect=[2, 2])
self.assertEqual(emb.extract(10), 0)
self.assertListEqual(emb.embed.call_args_list,
[call(10, 0), call(10, 1)])
def test_embedding_one(self):
quantizer = MagicMock(return_value=-30)
emb = BinaryDM(quantizer, d0=5)
# positive d(m)
emb.dither = Mock(return_value=4)
self.assertEqual(emb.embed(-25, 1), -34)
quantizer.assert_called_with(-21)
self.assertListEqual(emb.dither.call_args_list, [call(1), call(1)])
# negative d(m)
emb.dither = Mock(return_value=-4)
self.assertEqual(emb.embed(-25, 1), -26)
quantizer.assert_called_with(-29)
self.assertListEqual(emb.dither.call_args_list, [call(1), call(1)])
def test_embedding_cero(self):
quantizer = MagicMock(return_value=30)
emb = BinaryDM(quantizer, d0=5)
# positive d(m)
emb.dither = Mock(return_value=4)
self.assertEqual(emb.embed(25, 0), 26)
quantizer.assert_called_with(29)
self.assertListEqual(emb.dither.call_args_list, [call(0), call(0)])
# negative d(m)
emb.dither = Mock(return_value=-4)
self.assertEqual(emb.embed(25, 0), 34)
quantizer.assert_called_with(21)
self.assertListEqual(emb.dither.call_args_list, [call(0), call(0)])
def test_non_binary_data(self):
quantizer = MagicMock()
emb = BinaryDM(quantizer, d0=5)
with self.assertRaises(ValueError):
emb.embed(10, 5)