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Do include DC bin in Diopser spectrum

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Robbert van der Helm 2022-11-18 00:33:41 +01:00
parent 16dd364ec5
commit ba9b1f9e94
1 changed files with 6 additions and 6 deletions
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12
plugins/diopser/src/spectrum.rs
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@ -26,8 +26,9 @@ pub const SPECTRUM_WINDOW_SIZE: usize = 2048;
// Don't need that much precision here // Don't need that much precision here
const SPECTRUM_WINDOW_OVERLAP: usize = 2; const SPECTRUM_WINDOW_OVERLAP: usize = 2;
/// The amplitudes of all frequency bins in a windowed FFT of the input, minus the DC offset bin. /// The amplitudes of all frequency bins in a windowed FFT of the input. Also includes the DC offset
pub type Spectrum = [f32; SPECTRUM_WINDOW_SIZE / 2]; /// bin which we don't draw, just to make this a bit less confusing.
pub type Spectrum = [f32; SPECTRUM_WINDOW_SIZE / 2 + 1];
/// A receiver for a spectrum computed by [`SpectrumInput`]. /// A receiver for a spectrum computed by [`SpectrumInput`].
pub type SpectrumOutput = triple_buffer::Output<Spectrum>; pub type SpectrumOutput = triple_buffer::Output<Spectrum>;
@ -57,14 +58,14 @@ impl SpectrumInput {
/// Create a new spectrum input and output pair. The output should be moved to the editor. /// Create a new spectrum input and output pair. The output should be moved to the editor.
pub fn new(num_channels: usize) -> (SpectrumInput, SpectrumOutput) { pub fn new(num_channels: usize) -> (SpectrumInput, SpectrumOutput) {
let (triple_buffer_input, triple_buffer_output) = let (triple_buffer_input, triple_buffer_output) =
TripleBuffer::new(&[0.0; SPECTRUM_WINDOW_SIZE / 2]).split(); TripleBuffer::new(&[0.0; SPECTRUM_WINDOW_SIZE / 2 + 1]).split();
let input = Self { let input = Self {
stft: util::StftHelper::new(num_channels, SPECTRUM_WINDOW_SIZE, 0), stft: util::StftHelper::new(num_channels, SPECTRUM_WINDOW_SIZE, 0),
num_channels, num_channels,
triple_buffer_input, triple_buffer_input,
spectrum_result_buffer: [0.0; SPECTRUM_WINDOW_SIZE / 2], spectrum_result_buffer: [0.0; SPECTRUM_WINDOW_SIZE / 2 + 1],
plan: RealFftPlanner::new().plan_fft_forward(SPECTRUM_WINDOW_SIZE), plan: RealFftPlanner::new().plan_fft_forward(SPECTRUM_WINDOW_SIZE),
compensated_window_function: util::window::hann(SPECTRUM_WINDOW_SIZE) compensated_window_function: util::window::hann(SPECTRUM_WINDOW_SIZE)
@ -98,12 +99,11 @@ impl SpectrumInput {
// To be able to reuse `real_fft_scratch_buffer` this function is called per // To be able to reuse `real_fft_scratch_buffer` this function is called per
// channel, so we need to use the channel index to do any pre- or post-processing. // channel, so we need to use the channel index to do any pre- or post-processing.
// Gain compensation has already been baked into the window function. // Gain compensation has already been baked into the window function.
// TODO: This obviously needs a low-pass/moving average
if channel_idx == 0 { if channel_idx == 0 {
for (bin, spectrum_result) in self for (bin, spectrum_result) in self
.complex_fft_buffer .complex_fft_buffer
.iter() .iter()
// We don't care about the DC bin
.skip(1)
.zip(&mut self.spectrum_result_buffer) .zip(&mut self.spectrum_result_buffer)
{ {
*spectrum_result = bin.norm(); *spectrum_result = bin.norm();