mlxrs 0.1.0

Safe Rust bindings for Apple's MLX array framework, with LM, VLM, audio, and embeddings support
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//! STT per-domain load entry points, ported from
//! [`mlx_audio.stt.utils`][stt-utils].
//!
//! Faithful 1:1 of mlx-audio's two-tier shape:
//!
//! - [`load_model`] ([stt-utils.py:64-89][stt-utils-loadmodel]) — the
//!   inner factory call mlx-audio funnels into
//!   `base_load_model(model_path=…, category="stt",
//!   model_remapping=MODEL_REMAPPING, …)`.
//! - [`load`] ([stt-utils.py:92-115][stt-utils-load]) — the **main
//!   entry point**; thin alias over [`load_model`]. Carried for parity
//!   with `from mlx_audio.stt import load`.
//!
//! mlx-audio's `MODEL_REMAPPING` table ([stt-utils.py:12-26][stt-utils-remap])
//! routes per-architecture aliases (`cohere_asr`, `fireredasr2`, `glm`
//! → `glmasr`, `sensevoice`, `voxtral`, `voxtral_realtime`, `vibevoice`
//! → `vibevoice_asr`, `qwen3_asr`, `canary`, `moonshine`, `mms`,
//! `granite_speech`, `qwen2_audio`) into
//! `mlx_audio.stt.models.<arch>`; per the no-per-model-arch rule
//! mlxrs returns a [`crate::audio::stt::model::Model`] trait object the
//! per-architecture loader's caller constructs.
//!
//! [stt-utils]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py
//! [stt-utils-loadmodel]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L64-L89
//! [stt-utils-load]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L92-L115
//! [stt-utils-remap]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L12-L26

use crate::{
  audio::{
    load::{LoadedAudioModel, base_load_model},
    stt::model::Model as SttModel,
  },
  error::Result,
};

/// mlx-audio's documented sample rate for every STT architecture —
/// [stt-utils.py:10][stt-utils-sr] (`SAMPLE_RATE = 16000`).
///
/// Exposed here so a caller wiring a per-architecture STT model can
/// resample input audio to the model's expected rate without restating
/// the constant.
///
/// [stt-utils-sr]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L10
pub const STT_SAMPLE_RATE: u32 = 16_000;

/// The mlx-audio `MODEL_REMAPPING` table for STT architectures
/// ([stt-utils.py:12-26][stt-utils-remap]) — `(alias,
/// canonical_module_name)` pairs.
///
/// **Reference-only**: per the no per-model arch porting
/// rule, mlxrs does NOT import per-architecture crates from this table.
///
/// [stt-utils-remap]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L12-L26
pub const MODEL_REMAPPING: &[(&str, &str)] = &[
  ("cohere_asr", "cohere_asr"),
  ("fireredasr2", "fireredasr2"),
  ("glm", "glmasr"),
  ("sensevoice", "sensevoice"),
  ("voxtral", "voxtral"),
  ("voxtral_realtime", "voxtral_realtime"),
  ("vibevoice", "vibevoice_asr"),
  ("qwen3_asr", "qwen3_asr"),
  ("canary", "canary"),
  ("moonshine", "moonshine"),
  ("mms", "mms"),
  ("granite_speech", "granite_speech"),
  ("qwen2_audio", "qwen2_audio"),
];

/// Construct a [`SttModel`] from a local on-disk model directory —
/// faithful 1:1 of `mlx_audio.stt.utils.load_model`
/// ([stt-utils.py:64-89][stt-utils-loadmodel]).
///
/// Routes through the shared
/// [`crate::audio::load::base_load_model`] factory. The returned bundle
/// is handed to the caller-supplied `constructor` closure (per the
/// no per-model arch porting rule mlxrs does not bundle a
/// built-in registry).
///
/// `path` is the local on-disk path (a `hf://…` / `org/name` repo id is
/// rejected by [`crate::audio::load::get_model_path`] with a clear
/// no-network message).
///
/// Failures are typed: missing dir →
/// [`Error::MissingKey`](crate::error::Error::MissingKey), hub path →
/// [`Error::OutOfRange`](crate::error::Error::OutOfRange), malformed JSON →
/// [`Error::Parse`](crate::error::Error::Parse), constructor
/// error → caller-defined.
///
/// [stt-utils-loadmodel]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L64-L89
pub fn load_model<F>(path: &str, constructor: F) -> Result<Box<dyn SttModel>>
where
  F: FnOnce(LoadedAudioModel) -> Result<Box<dyn SttModel>>,
{
  let bundle = base_load_model(path)?;
  constructor(bundle)
}

/// The **main entry point** for loading an STT model — faithful 1:1 of
/// `mlx_audio.stt.utils.load` ([stt-utils.py:92-115][stt-utils-load]).
/// Thin alias over [`load_model`].
///
/// [stt-utils-load]: https://github.com/Blaizzy/mlx-audio/blob/main/mlx_audio/stt/utils.py#L92-L115
pub fn load<F>(path: &str, constructor: F) -> Result<Box<dyn SttModel>>
where
  F: FnOnce(LoadedAudioModel) -> Result<Box<dyn SttModel>>,
{
  load_model(path, constructor)
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::{
    array::Array,
    audio::stt::model::MelConfig,
    error::{Error, InvariantViolationPayload},
    lm::{cache::KvCache, model::Model as LmModel},
  };
  use std::{fs, path::PathBuf};

  /// A fake STT model. The `Model` super-trait (`crate::lm::model::Model`)
  /// is impl'd minimally so the test can construct one.
  struct FakeStt;

  impl LmModel for FakeStt {
    fn forward(&self, _tokens: &Array, _cache: &mut [Box<dyn KvCache>]) -> Result<Array> {
      Err(Error::InvariantViolation(InvariantViolationPayload::new(
        "FakeStt::forward",
        "test stub — unreachable in this test",
      )))
    }
  }

  impl SttModel for FakeStt {
    fn encode_audio(&self, _mel: &Array) -> Result<Array> {
      Array::from_slice::<f32>(&[0.0_f32; 4], &(1, 4))
    }
    fn mel_config(&self) -> MelConfig {
      MelConfig::whisper_default()
    }
    fn bos_token(&self) -> u32 {
      50258 // whisper's <|startoftranscript|>
    }
    fn eos_token(&self) -> u32 {
      50257 // whisper's <|endoftext|>
    }
  }

  fn temp_dir(name: &str) -> PathBuf {
    let dir = std::env::temp_dir().join(format!(
      "mlxrs_audio_stt_load_{}_{}",
      std::process::id(),
      name
    ));
    let _ = fs::remove_dir_all(&dir);
    fs::create_dir_all(&dir).unwrap();
    dir
  }

  /// Factory + smoke test: constructor receives the resolved bundle;
  /// trait object's metadata is functional (the per-model decode
  /// branches stay per-arch).
  #[test]
  fn load_stt_constructs_via_factory() {
    let dir = temp_dir("constructs_via_factory");
    let body = r#"{ "model_type": "whisper", "n_mels": 80 }"#;
    fs::write(dir.join("config.json"), body).unwrap();

    let captured: std::cell::RefCell<Option<PathBuf>> = std::cell::RefCell::new(None);
    let model = load(&dir.to_string_lossy(), |bundle| {
      *captured.borrow_mut() = Some(bundle.model_path().to_path_buf());
      Ok(Box::new(FakeStt))
    })
    .expect("load constructs via the supplied factory");

    assert_eq!(captured.into_inner().unwrap(), dir);
    assert_eq!(model.bos_token(), 50258);
    assert_eq!(model.eos_token(), 50257);
    assert_eq!(model.mel_config().sample_rate(), 16_000);
  }
}