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Fixed fft.cpp and added tests

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This commit is contained in:
paramthakkar123 2025-04-18 23:21:10 +05:30
parent c92a2bc679
commit 0db393acd7
2 changed files with 90 additions and 18 deletions
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34
mlx/fft.cpp
View File

@ -225,15 +225,13 @@ array stft(
int n_frames = 1 + (padded_x.shape(0) - n_fft) / hop_length;
std::vector<array> frames;
for (int i = 0; i < n_frames; ++i) {
array frame =
slice(padded_x, {i * hop_length}, {i * hop_length + n_fft}, s);
frames.push_back(multiply(frame, win, s));
}
array stacked_frames = stack(frames, 0, s);
Shape strided_shape = {n_frames, n_fft};
Strides strided_strides = {
hop_length * static_cast<long long>(sizeof(float32)),
static_cast<long long>(sizeof(float32))};
array frames = as_strided(padded_x, strided_shape, strided_strides, 0, s);
array stacked_frames = multiply(frames, win, s);
array stft_result = mlx::core::fft::rfftn(stacked_frames, {n_fft}, {-1}, s);
if (normalized) {
@ -273,23 +271,23 @@ array istft(
}
array frames = mlx::core::fft::irfftn(stft_matrix, {n_fft}, {-1}, s);
frames = multiply(frames, win, s);
int signal_length = (frames.shape(0) - 1) * hop_length + n_fft;
array signal = zeros({signal_length}, float32, s);
array window_sum = zeros({signal_length}, float32, s);
for (int i = 0; i < frames.shape(0); ++i) {
array frame = reshape(slice(frames, {i}, {i + 1}, s), {n_fft}, s);
array signal_slice =
slice(signal, {i * hop_length}, {i * hop_length + n_fft}, s);
array window_slice =
slice(window_sum, {i * hop_length}, {i * hop_length + n_fft}, s);
Shape strided_shape = {frames.shape(0), n_fft};
Strides strided_strides = {
hop_length * static_cast<long long>(sizeof(float32)),
static_cast<long long>(sizeof(float32))};
array signal_strided =
as_strided(signal, strided_shape, strided_strides, 0, s);
array window_sum_strided =
as_strided(window_sum, strided_shape, strided_strides, 0, s);
signal_slice = add(signal_slice, frame, s);
window_slice = add(window_slice, win, s);
}
signal_strided = add(signal_strided, frames, s);
window_sum_strided = add(window_sum_strided, win, s);
signal = divide(signal, window_sum, s);

74
tests/fft_tests.cpp
View File

@ -308,3 +308,77 @@ TEST_CASE("test fft grads") {
.second;
CHECK_EQ(vjp_out.shape(), Shape{5, 5});
}
TEST_CASE("test stft and istft") {
int n_fft = 4;
int hop_length = 2;
int win_length = 4;
array signal = array({1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0}, float32);
array window = array({0.5, 1.0, 1.0, 0.5}, float32);
SUBCASE("stft basic functionality") {
auto stft_result = fft::stft(signal, n_fft, hop_length, win_length, window);
CHECK_EQ(stft_result.shape(0), 4);
CHECK_EQ(stft_result.shape(1), 3);
CHECK_EQ(stft_result.dtype(), complex64);
}
SUBCASE("istft reconstruction") {
auto stft_result = fft::stft(signal, n_fft, hop_length, win_length, window);
auto reconstructed_signal =
fft::istft(stft_result, hop_length, win_length, window);
CHECK_EQ(reconstructed_signal.shape(0), signal.shape(0));
CHECK(allclose(signal, reconstructed_signal, 1e-5, 1e-5).item<bool>());
}
SUBCASE("stft with default parameters") {
auto stft_result = fft::stft(signal);
CHECK_EQ(stft_result.shape(0), 5);
CHECK_EQ(stft_result.shape(1), 3);
CHECK_EQ(stft_result.dtype(), complex64);
}
SUBCASE("istft with length parameter") {
auto stft_result = fft::stft(signal, n_fft, hop_length, win_length, window);
int length = 6;
auto reconstructed_signal =
fft::istft(stft_result, hop_length, win_length, window, true, length);
CHECK_EQ(reconstructed_signal.shape(0), length);
CHECK(
allclose(slice(signal, {0}, {length}), reconstructed_signal, 1e-5, 1e-5)
.item<bool>());
}
SUBCASE("stft and istft with normalization") {
auto stft_result = fft::stft(
signal, n_fft, hop_length, win_length, window, true, "reflect", true);
auto reconstructed_signal =
fft::istft(stft_result, hop_length, win_length, window, true, -1, true);
CHECK(allclose(signal, reconstructed_signal, 1e-5, 1e-5).item<bool>());
}
SUBCASE("stft with onesided=False") {
auto stft_result = fft::stft(
signal,
n_fft,
hop_length,
win_length,
window,
true,
"reflect",
false,
false);
CHECK_EQ(stft_result.shape(1), n_fft);
}
}