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//! Sample-rate conversion
use crate::bufferpool::*;
use crate::flow::*;
use crate::impl_block_trait;
use crate::math::*;
use crate::numbers::*;
use crate::signal::*;
use crate::windowing::{self, Window};
use tokio::task::spawn;
/// Reduce sample rate
pub struct Downsampler<Flt> {
receiver_connector: ReceiverConnector<Signal<Complex<Flt>>>,
sender_connector: SenderConnector<Signal<Complex<Flt>>>,
}
impl_block_trait! { <Flt> Consumer<Signal<Complex<Flt>>> for Downsampler<Flt> }
impl_block_trait! { <Flt> Producer<Signal<Complex<Flt>>> for Downsampler<Flt> }
impl<Flt> Downsampler<Flt>
where
Flt: Float,
{
/// Create new `Downsampler` block
///
/// This call corresponds to [`Downsampler::with_quality`] with a `quality`
/// value of `3.0`.
///
/// Connected [`Producer`]s must emit [`Signal::Samples`] with a
/// [`sample_rate`] equal to or higher than `output_rate`; otherwise a
/// panic occurs.
///
/// Aliasing is suppressed for frequencies lower than `bandwidth`.
///
/// [`sample_rate`]: Signal::Samples::sample_rate
pub fn new(output_chunk_len: usize, output_rate: f64, bandwidth: f64) -> Self {
Self::with_quality(output_chunk_len, output_rate, bandwidth, 3.0)
}
/// Create new `Downsampler` block with `quality` setting
///
/// Same as [`Downsampler::new`], but allows to specify a `quality`
/// setting, which must be equal to or greater than `1.0`.
pub fn with_quality(
output_chunk_len: usize,
output_rate: f64,
bandwidth: f64,
quality: f64,
) -> Self {
assert!(output_rate >= 0.0, "output sample rate must be positive");
assert!(bandwidth >= 0.0, "bandwidth must be positive");
assert!(
bandwidth < output_rate,
"bandwidth must be smaller than output sample rate"
);
let (mut receiver, receiver_connector) = new_receiver::<Signal<Complex<Flt>>>();
let (sender, sender_connector) = new_sender::<Signal<Complex<Flt>>>();
let mut buf_pool = ChunkBufPool::<Complex<Flt>>::new();
let mut output_chunk = buf_pool.get_with_capacity(output_chunk_len);
spawn(async move {
let margin = (output_rate - bandwidth) / 2.0;
let mut prev_input_rate: Option<f64> = None;
let mut ir: Vec<Flt> = Default::default();
let mut ringbuf: Vec<Complex<Flt>> = Default::default();
let mut ringbuf_pos: usize = Default::default();
let mut pos: f64 = Default::default();
loop {
let Ok(signal) = receiver.recv().await else { return; };
match signal {
Signal::Samples {
sample_rate: input_rate,
chunk: input_chunk,
} => {
if Some(input_rate) != prev_input_rate {
prev_input_rate = Some(input_rate);
assert!(input_rate >= 0.0, "input sample rate must be positive");
assert!(
input_rate >= output_rate,
"input sample rate must be greater than or equal to output sample rate"
);
let ir_len: usize = (input_rate / margin * quality).ceil() as usize;
assert!(ir_len > 0);
let ir_len_flt = ir_len as f64;
let window = windowing::Kaiser::with_null_at_bin(
ir_len_flt * margin / input_rate,
);
let mut ir_buf: Vec<f64> = Vec::with_capacity(ir_len);
let mut energy = 0.0;
for i in 0..ir_len {
let x = (i as f64 + 0.5) - ir_len_flt / 2.0;
let y = sinc(x * output_rate / input_rate)
* window.relative_value_at(x * 2.0 / ir_len_flt);
ir_buf.push(y);
energy += y * y;
}
let scale = energy.sqrt().recip();
ir = ir_buf.into_iter().map(|y| flt!(y * scale)).collect();
ringbuf = vec![Complex::from(Flt::zero()); ir_len];
ringbuf_pos = 0;
pos = 0.0;
}
for &sample in input_chunk.iter() {
ringbuf[ringbuf_pos] = sample;
ringbuf_pos += 1;
if ringbuf_pos == ir.len() {
ringbuf_pos = 0;
}
pos += output_rate;
if pos >= input_rate {
pos -= input_rate;
let mut sum: Complex<Flt> = Complex::from(Flt::zero());
let mut ir_iter = ir.iter();
let mut next_ir = || *ir_iter.next().unwrap();
for i in ringbuf_pos..ir.len() {
sum += ringbuf[i] * next_ir();
}
for i in 0..ringbuf_pos {
sum += ringbuf[i] * next_ir();
}
output_chunk.push(sum);
if output_chunk.len() >= output_chunk_len {
let Ok(()) = sender
.send(Signal::Samples {
sample_rate: output_rate,
chunk: output_chunk.finalize(),
})
.await
else { return; };
output_chunk = buf_pool.get_with_capacity(output_chunk_len);
}
}
}
}
event @ Signal::Event { .. } => {
let Ok(()) = sender.send(event).await else { return; };
}
}
}
});
Self {
receiver_connector,
sender_connector,
}
}
}
/// Increase sample rate
pub struct Upsampler<Flt> {
receiver_connector: ReceiverConnector<Signal<Complex<Flt>>>,
sender_connector: SenderConnector<Signal<Complex<Flt>>>,
}
impl_block_trait! { <Flt> Consumer<Signal<Complex<Flt>>> for Upsampler<Flt> }
impl_block_trait! { <Flt> Producer<Signal<Complex<Flt>>> for Upsampler<Flt> }
impl<Flt> Upsampler<Flt>
where
Flt: Float,
{
/// Create new `Upsampler` block
///
/// This call corresponds to [`Upsampler::with_quality`] with a `quality`
/// value of `3.0`.
///
/// Connected [`Producer`]s must emit [`Signal::Samples`] with a
/// [`sample_rate`] equal to or smaller than `output_rate` but larger than
/// `bandwidth`; otherwise a panic occurs.
///
/// Aliasing is suppressed for frequencies lower than `bandwidth`.
///
/// [`sample_rate`]: Signal::Samples::sample_rate
pub fn new(output_chunk_len: usize, output_rate: f64, bandwidth: f64) -> Self {
Self::with_quality(output_chunk_len, output_rate, bandwidth, 3.0)
}
/// Create new `Upsampler` block with `quality` setting
///
/// Same as [`Upsampler::new`], but allows to specify a `quality` setting,
/// which must be equal to or greater than `1.0`.
pub fn with_quality(
output_chunk_len: usize,
output_rate: f64,
bandwidth: f64,
quality: f64,
) -> Self {
assert!(output_rate >= 0.0, "output sample rate must be positive");
assert!(bandwidth >= 0.0, "bandwidth must be positive");
let (mut receiver, receiver_connector) = new_receiver::<Signal<Complex<Flt>>>();
let (sender, sender_connector) = new_sender::<Signal<Complex<Flt>>>();
let mut buf_pool = ChunkBufPool::<Complex<Flt>>::new();
let mut output_chunk = buf_pool.get_with_capacity(output_chunk_len);
spawn(async move {
let mut prev_input_rate: Option<f64> = None;
let mut ir: Vec<Flt> = Default::default();
let mut ringbuf: Vec<Complex<Flt>> = Default::default();
let mut ringbuf_pos: usize = Default::default();
let mut pos: f64 = Default::default();
loop {
let Ok(signal) = receiver.recv().await else { return; };
match signal {
Signal::Samples {
sample_rate: input_rate,
chunk: input_chunk,
} => {
if Some(input_rate) != prev_input_rate {
prev_input_rate = Some(input_rate);
assert!(input_rate >= 0.0, "input sample rate must be positive");
assert!(
input_rate <= output_rate,
"input sample rate must be smaller than or equal to output sample rate"
);
assert!(
bandwidth < input_rate,
"bandwidth must be smaller than input sample rate"
);
let margin = (input_rate - bandwidth) / 2.0;
let ir_len: usize = (output_rate / margin * quality).ceil() as usize;
assert!(ir_len > 0);
let ir_len_flt = ir_len as f64;
let window = windowing::Kaiser::with_null_at_bin(
ir_len_flt * margin / output_rate,
);
let mut ir_buf: Vec<f64> = Vec::with_capacity(ir_len);
let mut energy = 0.0;
for i in 0..ir_len {
let x = (i as f64 + 0.5) - ir_len_flt / 2.0;
let y = sinc(x * input_rate / output_rate)
* window.relative_value_at(x * 2.0 / ir_len_flt);
ir_buf.push(y);
energy += y * y;
}
let scale = energy.sqrt().recip();
ir = ir_buf.into_iter().map(|y| flt!(y * scale)).collect();
ringbuf = vec![Complex::from(Flt::zero()); ir_len];
ringbuf_pos = 0;
pos = 0.0;
}
for &sample in input_chunk.iter() {
let mut ir_iter = ir.iter();
let mut next_ir = || *ir_iter.next().unwrap();
for i in ringbuf_pos..ir.len() {
ringbuf[i] += sample * next_ir();
}
for i in 0..ringbuf_pos {
ringbuf[i] += sample * next_ir();
}
while pos < output_rate {
output_chunk.push(ringbuf[ringbuf_pos]);
ringbuf[ringbuf_pos] = Complex::from(Flt::zero());
if output_chunk.len() >= output_chunk_len {
let Ok(()) = sender
.send(Signal::Samples {
sample_rate: output_rate,
chunk: output_chunk.finalize(),
})
.await
else { return; };
output_chunk = buf_pool.get_with_capacity(output_chunk_len);
}
ringbuf_pos += 1;
if ringbuf_pos >= ir.len() {
ringbuf_pos = 0;
}
pos += input_rate;
}
pos -= output_rate;
}
}
event @ Signal::Event { .. } => {
let Ok(()) = sender.send(event).await else { return; };
}
}
}
});
Upsampler {
receiver_connector,
sender_connector,
}
}
}
#[cfg(test)]
mod tests {}