Redesign as a complete STFT/ISTFT toolkit (0.4, breaking)

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: cargo
+    directory: "/"
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 5
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly

.github/workflows/ci.yml

@@ -0,0 +1,95 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "-D warnings"
+
+jobs:
+  fmt:
+    name: rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - run: cargo fmt --all --check
+
+  clippy:
+    name: clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo clippy --all-targets --all-features
+      # The FFT processors (and thus examples/tests/benches) need `std`, so
+      # lint only the library for the no_std subsets.
+      - run: cargo clippy --lib --no-default-features
+      - run: cargo clippy --lib --no-default-features --features mel,serde
+
+  test:
+    name: test (${{ matrix.rust }})
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust: [stable, "1.85"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ matrix.rust }}
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo test --all-features
+      - run: cargo test # default features
+
+  no_std:
+    name: no_std build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: thumbv7em-none-eabihf
+      - run: cargo build --no-default-features --features mel,serde --target thumbv7em-none-eabihf
+
+  docs:
+    name: doc
+    runs-on: ubuntu-latest
+    env:
+      RUSTDOCFLAGS: "-D warnings --cfg docsrs"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cargo doc --all-features --no-deps
+
+  deny:
+    name: cargo-deny
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: EmbarkStudios/cargo-deny-action@v2
+
+  coverage:
+    name: coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: llvm-tools-preview
+      - uses: taiki-e/install-action@cargo-llvm-cov
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo llvm-cov --all-features --lcov --output-path lcov.info
+      - uses: codecov/codecov-action@v4
+        with:
+          files: lcov.info
+          fail_ci_if_error: false

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project are documented here. The format is based
+on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project
+adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.4.0]
+
+This is a ground-up redesign with a clean, encapsulated API. The old `STFT`
+type, `WindowType` enum, `FromF64` trait and `log10_positive` free function
+have been removed.
+
+### Added
+
+- `Istft` / `IstftBuilder`: inverse STFT with weighted overlap-add for perfect
+  reconstruction, plus `Stft::inverse()` to mirror a forward transform.
+- One-shot batch processing: `Stft::spectrogram()` returning a `Spectrogram`,
+  with optional centered framing (`reflect`/`edge`/`zero` padding) and optional
+  `rayon` parallelism.
+- A full window library (`Window`, `WindowFunction`, `Symmetry`): rectangular,
+  Hann, Hamming, Blackman, Blackman-Harris, Nuttall, flat-top, Bartlett,
+  triangular, Welch, cosine, Tukey, Kaiser and Gaussian, in periodic and
+  symmetric variants.
+- Coefficient scaling modes (`Scaling`: none, magnitude, density).
+- `spectrum` helpers: magnitude, power, phase, and decibel conversions.
+- `mel` feature: mel filterbank, mel scale conversions, and an orthonormal
+  DCT-II for MFCCs (librosa-compatible defaults).
+- Optional integrations: `ndarray` (`Array2` output), `rayon` (parallel batch),
+  `serde` (config (de)serialization).
+- `no_std` support (with `alloc`) for the window, spectrum and mel math.
+- `#![forbid(unsafe_code)]` across the crate.
+
+### Changed
+
+- Switched the FFT backend to `realfft`, roughly halving time and memory for
+  real-valued input.
+
+### Fixed
+
+- The number of frequency bins is now `fft_size / 2 + 1`, correctly including
+  the Nyquist bin (previously `fft_size / 2`, which dropped it).
+- Bin center frequencies are now `k · fs / fft_size` (previously
+  `k · fs / (2·(n_freqs − 1))`, which was off).
+
+[Unreleased]: https://github.com/sunsided/stft/compare/v0.4.0...HEAD
+[0.4.0]: https://github.com/sunsided/stft/compare/v0.3.1...v0.4.0

Cargo.toml

@@ -1,26 +1,65 @@
 [package]
-authors = ["Maximilian Krüger <kruemaxi@gmail.com>", "Markus Mayer <widemeadows@gmail.com>"]
-description = "computes the short-time fourier transform on streaming data"
+authors = [
+    "Maximilian Krüger <kruemaxi@gmail.com>",
+    "Markus Mayer <widemeadows@gmail.com>",
+]
+categories = ["science", "multimedia::audio", "mathematics", "no-std"]
+description = "Short-time Fourier transform (STFT) and inverse STFT: streaming and batch spectrograms, a rich window library, mel spectrograms and MFCCs."
 documentation = "https://docs.rs/ruststft"
+edition = "2021"
 homepage = "https://github.com/sunsided/stft"
-keywords = ["dsp", "fft", "stream", "data", "fourier"]
+keywords = ["dsp", "fft", "stft", "spectrogram", "mfcc"]
 license = "MIT OR Apache-2.0"
 name = "ruststft"
 readme = "README.md"
 repository = "https://github.com/sunsided/stft.git"
-version = "0.3.1"
-edition = "2021"
+rust-version = "1.85"
+version = "0.4.0"
+
+[features]
+default = ["std"]
+# Enables the FFT-backed processors (forward/inverse STFT, batch spectrograms).
+# Required because the `realfft`/`rustfft` backend depends on `std`.
+std = ["dep:realfft", "num-traits/std", "num-complex/std"]
+# Mel filterbank, (log-)mel spectrogram and MFCC. Pure math, `no_std`-capable.
+mel = []
+# `Array2` input/output for batch spectrograms. Pulls in `std`.
+ndarray = ["dep:ndarray", "std"]
+# Parallel per-frame batch STFT. Pulls in `std`.
+rayon = ["dep:rayon", "std"]
+# `serde` derives on the configuration and window-specification types.
+serde = ["dep:serde"]
+# Enable the WASM SIMD (`simd128`) FFT kernels. Implies `std`. Only takes
+# effect on `wasm32` targets built with `-C target-feature=+simd128`.
+wasm_simd = ["std", "realfft/wasm_simd"]
 
 [dependencies]
-apodize = "1.0.0"
-num = "0.4.0"
-rustfft = "6.1.0"
-strider = "0.1.3"
+num-complex = { version = "0.4.6", default-features = false, features = ["libm"] }
+num-traits = { version = "0.2.19", default-features = false, features = ["libm"] }
+realfft = { version = "3.4.0", optional = true }
+ndarray = { version = "0.16.1", optional = true, default-features = false, features = ["std"] }
+rayon = { version = "1.10.0", optional = true }
+serde = { version = "1.0", optional = true, default-features = false, features = ["derive", "alloc"] }
 
 [dev-dependencies]
-criterion = "0.5.1"
 approx = "0.5.1"
+criterion = "0.5.1"
+proptest = "1.6.0"
 
 [[bench]]
 name = "lib"
 harness = false
+
+[[example]]
+name = "mfcc"
+required-features = ["mel"]
+
+[lints.rust]
+unsafe_code = "forbid"
+
+[lints.clippy]
+all = "deny"
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]