mvp (minimum vibrational production)

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "hound"
+version = "3.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62adaabb884c94955b19907d60019f4e145d091c75345379e70d1ee696f7854f"
+
+[[package]]
+name = "rpip7"
+version = "0.1.0"
+dependencies = [
+ "hound",
+]

Cargo.toml

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+[package]
+name = "rpip7"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+hound = "3.5.1"

src/main.rs

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+#![allow(
+    clippy::cast_possible_truncation,
+    clippy::cast_sign_loss,
+    clippy::cast_possible_wrap,
+    clippy::cast_precision_loss
+)]
+
+use std::{
+    env,
+    f32::consts::PI,
+    io::{self, Read},
+    num::NonZero,
+};
+
+#[derive(Debug)]
+struct Note {
+    freq: u16,
+    beats: NonZero<u16>,
+}
+
+impl Note {
+    fn rest() -> Self {
+        Self {
+            freq: 0,
+            beats: NonZero::<u16>::MIN,
+        }
+    }
+}
+
+struct Parser<'a> {
+    src: &'a [u8],
+}
+
+impl<'a> Parser<'a> {
+    fn new(src: &'a [u8]) -> Self {
+        Self { src }
+    }
+}
+
+impl Iterator for Parser<'_> {
+    type Item = Note;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let first = *self.src.first()?;
+        self.src = &self.src[1..];
+
+        if first == b' ' {
+            return Some(Note::rest());
+        }
+
+        let Some(n) = b"1234567drmfsltDRMSFLT".iter().position(|b| *b == first) else {
+            // skip invalid byte
+            return self.next();
+        };
+        let a4_pos = 12.;
+        let n = n as f32 - a4_pos;
+        let freq = 440. * 2.0f32.powf(n / 12.);
+        let freq = freq.floor() as u16;
+        let beats = self.src.iter().take_while(|b| **b == b'-').count();
+        let beats = NonZero::<u16>::new(beats as u16 + 1).unwrap();
+
+        Some(Note { freq, beats })
+    }
+}
+
+fn main() {
+    let beats_per_minute: f32 = env::args()
+        .nth(1)
+        .expect("give me bpm")
+        .parse()
+        .expect("bpm is a number please");
+    let beats_per_second = beats_per_minute / 60.;
+
+    let output_path = env::args().nth(2).expect("give me a path");
+
+    let mut src = String::new();
+    io::stdin().read_to_string(&mut src).unwrap();
+
+    let spec = hound::WavSpec {
+        channels: 1,
+        sample_rate: 44100,
+        bits_per_sample: 16,
+        sample_format: hound::SampleFormat::Int,
+    };
+
+    let mut writer = hound::WavWriter::create(output_path, spec).unwrap();
+
+    for note in Parser::new(src.as_bytes()) {
+        let freq = f32::from(note.freq);
+        let amplitude = f32::from(i16::MAX);
+
+        let samples = (spec.sample_rate * u32::from(note.beats.get())) / beats_per_second as u32;
+
+        for t in (0..samples).map(|x| x as f32 / (spec.sample_rate as f32)) {
+            let sample = (t * freq * 2.0 * PI).sin();
+            writer.write_sample((sample * amplitude) as i16).unwrap();
+        }
+    }
+}