audio input and fft

src/main.rs

@@ -1,3 +1,67 @@
-fn main() {
-    println!("Hello, world!");
+use std::{thread::sleep, time::Duration};
+
+use color_eyre::eyre::bail;
+use cpal::{
+    traits::{DeviceTrait, HostTrait, StreamTrait},
+    BufferSize, HostId, SupportedBufferSize,
+};
+use log::{debug, error, info, trace};
+use rustfft::{num_complex::Complex, FftPlanner};
+
+fn main() -> color_eyre::Result<()> {
+    env_logger::init();
+    debug!("Starting");
+
+    let mut hosts = cpal::platform::available_hosts();
+    hosts.sort_unstable_by_key(|host| match host {
+        HostId::Jack => 0,
+        HostId::Alsa => 1,
+    });
+    let host_id = hosts[0];
+    info!("Selected {host_id:?} audio backend");
+    let host = cpal::platform::host_from_id(host_id)?;
+
+    let Some(device) = host.default_input_device() else {
+        error!("Unable to get default input device for {host_id:?}");
+        bail!("Unable to get default input device")
+    };
+    debug!("Got default input device {:?}", device.name());
+
+    let default_config = device.default_input_config()?;
+    trace!("Default config {:?}", default_config);
+    let mut config = default_config.config();
+    let buffer_size =
+        if let SupportedBufferSize::Range { min, max: _ } = default_config.buffer_size() {
+            *min
+        } else {
+            1024
+        };
+    config.buffer_size = BufferSize::Fixed(buffer_size);
+    config.channels = 1;
+    debug!("Using config {config:?}");
+
+    let mut planner = FftPlanner::<f32>::new();
+    let fft = planner.plan_fft_forward(buffer_size as usize);
+    let mut fft_data = vec![Complex::new(0.0, 0.0); buffer_size as usize];
+    let mut fft_scratch = vec![Complex::new(0.0, 0.0); buffer_size as usize];
+
+    let stream = device.build_input_stream(
+        &config,
+        move |data: &[f32], _| {
+            for i in 0..data.len() {
+                fft_data[i] = Complex::new(data[i], 0.0);
+            }
+            fft.process_with_scratch(&mut fft_data[..], &mut fft_scratch[..]);
+        },
+        |err| {
+            error!("input stream error: {err}");
+        },
+        None,
+    )?;
+
+    stream.play()?;
+
+    loop {
+        sleep(Duration::from_secs(1));
+    }
 }