audio-codec

A collection of VoIP audio codecs implemented for Rust. This crate provides a unified interface for encoding and decoding various audio formats commonly used in SIP, VoIP, and WebRTC applications.

Supported Codecs

Codec	Implementation	Feature
G.711 (PCMA/PCMU)	Pure Rust	Built-in
G.722	Pure Rust	Built-in
G.729	Pure Rust (g729-sys)	Built-in
Opus	Pure Rust (opus-rs)	opus (default)
Telephone Event	RFC 4733	Built-in

Features

• Unified API: Simple Encoder and Decoder traits for all codecs.
• Resampler: Built-in audio resampling utility.
• Lightweight: Minimal dependencies for core codecs.

Performance

Measured on Apple M2 Pro (processing 20ms audio frames):

Codec	Encode (20ms)	Decode (20ms)	Rate
PCMU	~50.09 ns	~59.73 ns	8kHz
PCMA	~50.23 ns	~59.63 ns	8kHz
G.722	~5.02 µs	~3.82 µs	16kHz
G.729	~20.50 µs	~6.16 µs	8kHz
Opus	~52.34 µs	~23.19 µs	48kHz

Note: Benchmarks were run with cargo bench --bench codec_bench (Criterion). create_encoder(CodecType::Opus) currently uses the default Opus profile: 48kHz, stereo, Application::Audio, bitrate 64kbps, complexity 5.

Usage

Add this to your Cargo.toml:

[dependencies]
audio-codec = "0.3"

Example: Decoding PCMA

use audio_codec::{create_decoder, CodecType};

fn main() {
    let mut decoder = create_decoder(CodecType::PCMA);
    let encoded_data: Vec<u8> = vec![/* ... */];
    let pcm_samples = decoder.decode(&encoded_data);
    
    println!("Decoded {} samples", pcm_samples.len());
}

Example: Encoding G.722

use audio_codec::{create_encoder, CodecType, Encoder};

fn main() {
    let mut encoder = create_encoder(CodecType::G722);
    let pcm_samples: Vec<i16> = vec![0; 320]; // 20ms @ 16kHz mono
    let encoded_data = encoder.encode(&pcm_samples);
    
    println!("Encoded into {} bytes", encoded_data.len());
}

Example: Configuring Opus (Factory API)

use audio_codec::{
    create_opus_decoder, create_opus_encoder, Decoder, Encoder,
    opus::OpusApplication,
};

fn main() {
    // Explicit Opus encoder/decoder creation
    // 48kHz stereo, Audio mode
    let mut encoder = create_opus_encoder(48_000, 2, OpusApplication::Audio);
    let mut decoder = create_opus_decoder(48_000, 2);

    let pcm_samples: Vec<i16> = vec![0; 960 * 2]; // 20ms @ 48kHz, interleaved stereo
    let encoded_data = encoder.encode(&pcm_samples);
    let decoded_pcm = decoder.decode(&encoded_data);

    println!("Encoded into {} bytes", encoded_data.len());
    println!("Decoded {} samples", decoded_pcm.len());
}

License

This project is licensed under the MIT License.