cpal/examples/beep.rs

62 lines
1.8 KiB
Rust

extern crate anyhow;
extern crate cpal;
use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
fn main() -> Result<(), anyhow::Error> {
let host = cpal::default_host();
let device = host
.default_output_device()
.expect("failed to find a default output device");
let format = device.default_output_format()?;
let sample_rate = format.sample_rate.0 as f32;
let channels = format.channels as usize;
// Produce a sinusoid of maximum amplitude.
let mut sample_clock = 0f32;
let mut next_value = move || {
sample_clock = (sample_clock + 1.0) % sample_rate;
(sample_clock * 440.0 * 2.0 * 3.141592 / sample_rate).sin()
};
let err_fn = |err| {
eprintln!("an error occurred on stream: {}", err);
};
let stream = match format.data_type {
cpal::SampleFormat::F32 => device.build_output_stream(
&format,
move |mut data| write_data::<f32>(&mut *data, channels, &mut next_value),
err_fn,
),
cpal::SampleFormat::I16 => device.build_output_stream(
&format,
move |mut data| write_data::<i16>(&mut *data, channels, &mut next_value),
err_fn,
),
cpal::SampleFormat::U16 => device.build_output_stream(
&format,
move |mut data| write_data::<u16>(&mut *data, channels, &mut next_value),
err_fn,
),
}?;
stream.play()?;
std::thread::sleep(std::time::Duration::from_millis(1000));
Ok(())
}
fn write_data<T>(output: &mut [T], channels: usize, next_sample: &mut dyn FnMut() -> f32)
where
T: cpal::Sample,
{
for frame in output.chunks_mut(channels) {
let value: T = cpal::Sample::from::<f32>(&next_sample());
for sample in frame.iter_mut() {
*sample = value;
}
}
}