wavo 0.1.0

Speech-to-text in pure Rust on the GPU (Metal, Vulkan): Parakeet, GigaAM and Whisper, as a library and an ollama-like CLI.
Documentation 
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// Copyright (c) vladkens | MIT License | https://github.com/vladkens/wavo
//! The models `wavo` knows by name: the Q8_0 GGUFs transcribe.cpp publishes as
//! `handy-computer/<variant>-gguf`, with sizes from its `catalog/<variant>.json`.

use std::io::Read;
use std::path::{Path, PathBuf};

use anyhow::{Result, bail};

pub struct Model {
  /// Short name; the published variant name is accepted too.
  pub name: &'static str,
  pub variant: &'static str,
  pub size: u64,
  pub about: &'static str,
}

impl Model {
  pub fn repo(&self) -> String {
    format!("handy-computer/{}-gguf", self.variant)
  }

  pub fn file(&self) -> String {
    format!("{}-Q8_0.gguf", self.variant)
  }
}

pub const DEFAULT: &str = "parakeet-v3";

#[rustfmt::skip]
pub const MODELS: &[Model] = &[
  Model { name: "parakeet-v3", variant: "parakeet-tdt-0.6b-v3", size: 739_508_576, about: "25 European languages" },
  Model { name: "parakeet-v2", variant: "parakeet-tdt-0.6b-v2", size: 729_574_912, about: "English" },
  Model { name: "gigaam-v3", variant: "gigaam-v3-e2e-rnnt", size: 273_724_832, about: "Russian" },
  Model { name: "gigaam-v3-e2e-ctc", variant: "gigaam-v3-e2e-ctc", size: 272_151_136, about: "Russian, CTC head" },
  Model { name: "gigaam-v3-rnnt", variant: "gigaam-v3-rnnt", size: 273_022_880, about: "Russian, lowercase without punctuation" },
  Model { name: "gigaam-v3-ctc", variant: "gigaam-v3-ctc", size: 271_803_328, about: "Russian, lowercase without punctuation, CTC head" },
  Model { name: "whisper-turbo", variant: "whisper-large-v3-turbo", size: 886_381_760, about: "100 languages" },
];

/// What a MODEL argument names.
pub enum Source {
  Path(PathBuf),
  Model(&'static Model),
}

pub fn find(name: &str) -> Option<&'static Model> {
  MODELS.iter().find(|m| m.name == name || m.variant == name)
}

/// A path when the argument ends in `.gguf` or has a path separator, else a known name.
pub fn resolve(arg: &str) -> Result<Source> {
  if arg.ends_with(".gguf") || arg.contains(['/', '\\']) {
    return Ok(Source::Path(arg.into()));
  }
  if let Some(model) = find(arg) {
    return Ok(Source::Model(model));
  }
  let names = MODELS.iter().map(|m| m.name).collect::<Vec<_>>().join(", ");
  let closest = (MODELS.iter().flat_map(|m| [m.name, m.variant]))
    .map(|n| (distance(arg, n), n))
    .min()
    .filter(|&(d, n)| d <= (n.len() / 3).max(2));
  match closest {
    Some((_, n)) => bail!("unknown model {arg:?}, did you mean {n}? Known models: {names}"),
    None => bail!("unknown model {arg:?}. Known models: {names}"),
  }
}

/// Levenshtein distance.
fn distance(a: &str, b: &str) -> usize {
  let b: Vec<char> = b.chars().collect();
  let mut row: Vec<usize> = (0..=b.len()).collect();
  for (i, ca) in a.chars().enumerate() {
    let mut diag = row[0];
    row[0] = i + 1;
    for (j, &cb) in b.iter().enumerate() {
      let next = (diag + (ca != cb) as usize).min(row[j] + 1).min(row[j + 1] + 1);
      diag = row[j + 1];
      row[j + 1] = next;
    }
  }
  row[b.len()]
}

/// The model file's `general.architecture` (`whisper`, `gigaam`, …), from its GGUF metadata:
/// the key-value pairs are read in order, skipping other values, until the key turns up.
pub fn architecture(path: &Path) -> Option<String> {
  let mut f = std::io::BufReader::new(std::fs::File::open(path).ok()?);
  let mut magic = [0; 4];
  f.read_exact(&mut magic).ok()?;
  (magic == *b"GGUF").then_some(())?;
  let (_version, _tensors, kvs) = (int::<4>(&mut f)?, int::<8>(&mut f)?, int::<8>(&mut f)?);
  for _ in 0..kvs {
    let key = string(&mut f)?;
    let ty = int::<4>(&mut f)?;
    if key == b"general.architecture" && ty == 8 {
      return String::from_utf8(string(&mut f)?).ok();
    }
    skip(&mut f, ty)?;
  }
  None
}

/// A little-endian unsigned integer of `N` bytes.
fn int<const N: usize>(f: &mut impl Read) -> Option<u64> {
  let mut b = [0; 8];
  f.read_exact(&mut b[..N]).ok()?;
  Some(u64::from_le_bytes(b))
}

fn string(f: &mut impl Read) -> Option<Vec<u8>> {
  let mut s = vec![0; int::<8>(f)? as usize];
  f.read_exact(&mut s).ok()?;
  Some(s)
}

/// Skips one GGUF value of type `ty`: scalars 0–7 and 10–12, a string 8, an array 9.
fn skip(f: &mut impl Read, ty: u64) -> Option<()> {
  match ty {
    0 | 1 | 7 => int::<1>(f).map(drop),
    2 | 3 => int::<2>(f).map(drop),
    4..=6 => int::<4>(f).map(drop),
    10..=12 => int::<8>(f).map(drop),
    8 => string(f).map(drop),
    9 => {
      let (ty, n) = (int::<4>(f)?, int::<8>(f)?);
      (0..n).try_for_each(|_| skip(f, ty))
    }
    _ => None,
  }
}

pub fn gb(bytes: u64) -> String {
  format!("{:.2} GB", bytes as f64 / 1e9)
}

#[cfg(test)]
mod tests {
  use std::path::Path;

  use super::*;

  fn name(arg: &str) -> &'static str {
    match resolve(arg).unwrap() {
      Source::Model(m) => m.name,
      Source::Path(p) => panic!("{arg} resolved to the path {p:?}"),
    }
  }

  fn error(arg: &str) -> String {
    resolve(arg).err().expect("an error").to_string()
  }

  #[test]
  fn architecture_from_the_header() {
    let mut gguf = b"GGUF\x03\0\0\0".to_vec();
    gguf.extend(0u64.to_le_bytes()); // tensors
    gguf.extend(2u64.to_le_bytes()); // keys
    // A description that mentions the key comes first and must not match.
    gguf.extend(19u64.to_le_bytes());
    gguf.extend(b"general.description");
    gguf.extend(8u32.to_le_bytes());
    gguf.extend(27u64.to_le_bytes());
    gguf.extend(b"has a general.architecture!");
    gguf.extend(20u64.to_le_bytes());
    gguf.extend(b"general.architecture");
    gguf.extend(8u32.to_le_bytes());
    gguf.extend(7u64.to_le_bytes());
    gguf.extend(b"whisper");
    let path = std::env::temp_dir().join(format!("wavo-arch-{}.gguf", std::process::id()));
    std::fs::write(&path, &gguf).unwrap();
    assert_eq!(architecture(&path).as_deref(), Some("whisper"));
    std::fs::write(&path, b"GGUF").unwrap();
    assert_eq!(architecture(&path), None);
    std::fs::remove_file(path).unwrap();
  }

  #[test]
  fn short_and_full_names() {
    assert_eq!(name("parakeet-v3"), "parakeet-v3");
    assert_eq!(name("parakeet-tdt-0.6b-v3"), "parakeet-v3");
    assert_eq!(name("gigaam-v3"), "gigaam-v3");
    assert_eq!(name("gigaam-v3-e2e-rnnt"), "gigaam-v3");
    assert_eq!(name("gigaam-v3-ctc"), "gigaam-v3-ctc");
    assert_eq!(find(DEFAULT).unwrap().variant, "parakeet-tdt-0.6b-v3");
    let m = find("gigaam-v3").unwrap();
    assert_eq!(m.repo(), "handy-computer/gigaam-v3-e2e-rnnt-gguf");
    assert_eq!(m.file(), "gigaam-v3-e2e-rnnt-Q8_0.gguf");
    assert_eq!(name("whisper-large-v3-turbo"), "whisper-turbo");
    let m = find("whisper-turbo").unwrap();
    assert_eq!(m.repo(), "handy-computer/whisper-large-v3-turbo-gguf");
    assert_eq!(m.file(), "whisper-large-v3-turbo-Q8_0.gguf");
  }

  #[test]
  fn names_are_unambiguous() {
    for (i, a) in MODELS.iter().enumerate() {
      for b in &MODELS[i + 1..] {
        for n in [b.name, b.variant] {
          assert!(a.name != n && a.variant != n, "{} and {} share {n}", a.variant, b.variant);
        }
      }
    }
  }

  #[test]
  fn paths() {
    for arg in ["model.gguf", "./model", "dir/x", r"C:\models\x.GGUF", "a\\b"] {
      assert!(matches!(resolve(arg), Ok(Source::Path(p)) if p == Path::new(arg)), "{arg}");
    }
  }

  #[test]
  fn unknown_names() {
    assert!(error("parakeet3").contains("did you mean parakeet-v3?"));
    assert!(error("gigam-v3").contains("did you mean gigaam-v3?"));
    assert!(error("parakeet-tdt-06b-v3").contains("did you mean parakeet-tdt-0.6b-v3?"));
    let e = error("whisper");
    assert!(!e.contains("did you mean") && e.contains("Known models: parakeet-v3, "), "{e}");
    assert_eq!(distance("kitten", "sitting"), 3);
    assert_eq!(distance("", "abc"), 3);
  }
}