# oximedia-audio
Audio codec implementations and DSP tools for the OxiMedia multimedia framework.
Part of the [oximedia](https://github.com/cool-japan/oximedia) workspace — a comprehensive pure-Rust media processing framework.
Version: 0.2.1 — 2026-08-12 — extensively tested
## Overview
`oximedia-audio` provides encoding and decoding for royalty-free audio codecs, plus a comprehensive suite of DSP, effects, metering, spatial audio, and analysis tools.
| Opus | Yes | Yes | Modern, high-quality codec for speech and music |
| Vorbis | Yes | — | Ogg Vorbis lossy codec |
| FLAC | Yes | — | Free Lossless Audio Codec |
| MP3 | Yes | — | MPEG-1/2 Layer III (patents expired 2017) |
| PCM | Yes | Yes | Uncompressed audio |
## Features
### Codec Support
Enable specific codecs via Cargo features (all enabled by default):
```toml
[dependencies]
oximedia-audio = { version = "0.2.0", features = ["opus", "vorbis", "flac", "mp3"] }
```
### DSP
The `dsp` module provides standalone digital signal processing:
- Biquad Filters — Second-order IIR filters
- Parametric Equalizer — Multi-band EQ
- Dynamics Compressor — Full-featured compressor
- Reverb — Schroeder reverb algorithm
### Effects
The `effects` module provides modulation effects:
- Chorus — Multi-voice chorus with LFO modulation
- Flanger — Short delay with feedback and sweeping
- Phaser — All-pass filter cascade for phase shifting
### Spectrum Analysis
The `spectrum` module provides frequency-domain analysis:
- FFT Analysis — Fast Fourier Transform with window functions
- Spectrum Analyzer — Real-time frequency analysis
- Spectrogram — Time-frequency visualization
- Waveform Display — Time-domain rendering
- Feature Extraction — Spectral features and characteristics
### Audio Fingerprinting
The `fingerprint` module provides audio identification:
- Fingerprint Generation — Extract robust audio signatures
- Hash-based Matching — Fast database lookup
- Duplicate Detection — Find similar audio content
### Loudness Normalization
The `loudness` module provides broadcast-standard measurement:
- EBU R128 — European Broadcasting Union standard (-23 LUFS)
- ATSC A/85 — Advanced Television Systems Committee standard (-24 LKFS)
- ITU-R BS.1770-4 — International loudness measurement algorithm
- True Peak Detection — Prevents inter-sample clipping
- Loudness Range (LRA) — Dynamic range measurement
- K-Weighting Filter — Perceptually accurate filtering
### Audio Metering
The `meters` module provides professional metering tools:
- VU Meter — IEC 60268-10 standard with 300ms ballistics
- PPM — Peak Programme Meters (BBC, EBU, Nordic, DIN standards)
- Digital Peak Meter — Sample-accurate dBFS peak detection
- RMS Level Meter — Root mean square level measurement
- Correlation Meter — Stereo phase correlation analysis
- Goniometer — Stereo field visualization (L/R and M/S)
- LUFS Integration — Broadcast loudness metering
### Spatial Audio
The `spatial` module provides 3D spatial audio processing (binaural, ambisonics, HRTF-based panning).
### Resampling
High-quality sample rate conversion via a Pure-Rust band-limited
windowed-sinc polyphase interpolator (Blackman-Harris windowed, per-phase
DC-normalized, exact rational position tracking — no C/C++ dependencies):
```rust
use oximedia_audio::{Resampler, ResamplerQuality};
let mut resampler = Resampler::new(44100, 48000, 2, ResamplerQuality::High)?;
let output = resampler.resample(&input_frame)?;
let tail = resampler.flush()?; // drain stream tail at end of input
```
## Usage
### Opus Decoding
```rust
use oximedia_audio::OpusDecoder;
let mut decoder = OpusDecoder::new(48000, 2)?;
let frame = decoder.decode(&packet)?;
```
### Opus Encoding
```rust
use oximedia_audio::OpusEncoder;
let mut encoder = OpusEncoder::new(48000, 2, 128_000)?;
let packet = encoder.encode(&frame)?;
```
### FLAC Decoding
```rust
use oximedia_audio::FlacDecoder;
let mut decoder = FlacDecoder::new(&stream_info)?;
let frame = decoder.decode(&packet)?;
```
### Audio Frame
```rust
use oximedia_audio::{AudioFrame, ChannelLayout};
let frame = AudioFrame::new(
48000, // sample rate
1024, // samples per channel
ChannelLayout::Stereo,
);
```
## Channel Layouts
| Mono | 1 | Single channel |
| Stereo | 2 | Left, Right |
| Surround5_1 | 6 | FL, FR, FC, LFE, BL, BR |
| Surround7_1 | 8 | FL, FR, FC, LFE, BL, BR, SL, SR |
## Module Structure (115 source files, 2266 public items)
```
src/
├── lib.rs # Crate root with re-exports
├── error.rs # AudioError and AudioResult
├── frame.rs # AudioFrame, AudioBuffer
├── traits.rs # AudioDecoder, AudioEncoder traits
├── resample.rs # Sample rate conversion (Pure-Rust windowed-sinc)
├── dsp/ # Digital signal processing
├── effects/ # Modulation effects
├── spectrum/ # Frequency-domain analysis
├── fingerprint/ # Audio fingerprinting
├── loudness/ # EBU R128 / ATSC A/85 / ITU-R BS.1770
├── meters/ # Professional audio metering
├── spatial/ # 3D spatial audio processing
├── opus/ # Opus codec (feature: opus)
├── vorbis/ # Vorbis codec (feature: vorbis)
├── flac/ # FLAC codec (feature: flac)
├── mp3/ # MP3 codec (feature: mp3)
└── pcm/ # PCM codec (feature: pcm)
```
## Codec Traits
```rust
pub trait AudioDecoder {
fn decode(&mut self, packet: &[u8]) -> AudioResult<AudioFrame>;
fn flush(&mut self) -> AudioResult<Vec<AudioFrame>>;
}
pub trait AudioEncoder {
fn encode(&mut self, frame: &AudioFrame) -> AudioResult<Vec<u8>>;
fn flush(&mut self) -> AudioResult<Vec<Vec<u8>>>;
}
```
## Policy
- No unsafe code (`#![forbid(unsafe_code)]`)
- Apache-2.0 license
## License
Apache-2.0 — Copyright 2024-2026 COOLJAPAN OU (Team Kitasan)