avioflow 0.3.5

High-performance audio decoding with FFmpeg and C++

AvioFlow

AvioFlow is a high-performance and easy-to-use streaming audio decoding library.

Features

• Audio format: mp3, opus, flac, ogg, wav, m4a, acc. Anything.
• Flexible Input: Files, URLs, memory buffers, and real-time streams
• Hardware Capture: WASAPI loopback (system audio) and DirectShow (microphones)
• Resampling: Built-in sample rate conversion
• Zero-copy API: Direct buffer access via FrameData for maximum performance
• Cross-platform: Windows, Linux, macOS

Supported language

C++
python	pybind11	pip install avioflow
JavaScript	node-add-api	npm install avioflow
Java	JNI	Gradle/Maven
	wasm
	vsix

Installation

Python

pip install avioflow

Java

Gradle users need the main Java API jar plus one native classifier for the target platform:

dependencies {
    implementation("io.github.lxp3:avioflow:0.3.5")
    runtimeOnly("io.github.lxp3:avioflow:0.3.5:linux-x86_64")
}

Maven:

<dependency>
  <groupId>io.github.lxp3</groupId>
  <artifactId>avioflow</artifactId>
  <version>0.3.2</version>
</dependency>
<dependency>
  <groupId>io.github.lxp3</groupId>
  <artifactId>avioflow</artifactId>
  <version>0.3.2</version>
  <classifier>linux-x86_64</classifier>
  <scope>runtime</scope>
</dependency>

Native classifiers: linux-x86_64, linux-aarch64, macos-x86_64, macos-aarch64, windows-x86_64, windows-aarch64.

C++ (CMake)

Download the C++ package for your platform and linkage, then point CMake at the extracted package root with CMAKE_PREFIX_PATH.

find_package(avioflow CONFIG REQUIRED)
target_link_libraries(your_target PRIVATE avioflow::avioflow)

Release packages are split by linkage and platform:

• avioflow-shared-linux-x64, avioflow-static-linux-x64
• avioflow-shared-linux-arm64, avioflow-static-linux-arm64
• avioflow-shared-macos-x64, avioflow-static-macos-x64
• avioflow-shared-macos-arm64, avioflow-static-macos-arm64
• avioflow-shared-win-x64, avioflow-static-win-x64
• avioflow-shared-win-arm64, avioflow-static-win-arm64

Shared packages include the FFmpeg dynamic libraries needed at runtime. Static packages include FFmpeg static libraries, transitive static dependency metadata, and the bundled FFmpeg CMake package, so consumers do not need to configure FFmpeg separately.

---

C++ API

Core Classes

AudioDecoder

Main class for audio decoding.

#include "avioflow-cxx-api.h"
using namespace avioflow;

// Constructor options
AudioStreamOptions options;
options.output_sample_rate = 16000;    // Target sample rate
options.input_format = "s16le";        // For streaming: source format
options.input_sample_rate = 48000;     // For streaming: source rate
options.input_channels = 2;            // For streaming: source channels

AudioDecoder decoder(options);

Methods

Method	Description
open(source)	Open file path, URL, or device
push(data, size)	Push raw bytes for streaming decode
read()	Decode next frame, returns FrameData. (Formerly decode_next)
get_samples()	Decode all currently available samples. (Formerly get_samples)
get_metadata()	Get audio metadata
is_finished()	Check if EOF reached

FrameData

Zero-copy frame data structure returned by read().

struct FrameData {
    float** data;        // Planar channel pointers: data[channel][sample]
    int num_channels;    // Number of channels
    int num_samples;     // Samples per channel

    operator bool();     // True if valid data
};

⚠️ Warning: FrameData.data points to internal buffer, valid only until next read() call.

Examples

File Decoding (Offline)

AudioDecoder decoder({.output_sample_rate = 16000});
decoder.open("audio.mp3");

auto samples = decoder.get_samples();  // vector<vector<float>>
std::cout << "Channels: " << samples.size() << std::endl;
std::cout << "Samples: " << samples[0].size() << std::endl;

Frame-by-Frame Decoding

AudioDecoder decoder;
decoder.open("audio.mp3");

while (auto frame = decoder.read()) {
    // frame.data[channel][sample]
    for (int c = 0; c < frame.num_channels; c++) {
        process(frame.data[c], frame.num_samples);
    }
}

Streaming Decode (Push-based)

AudioStreamOptions opts;
opts.input_format = "s16le";
opts.input_sample_rate = 48000;
opts.input_channels = 2;

AudioDecoder decoder(opts);
decoder.push(raw_bytes, size);  // Auto-initializes on first call

auto samples = decoder.get_samples(); // Decode all buffered data
// Or frame-by-frame:
while (auto frame = decoder.read()) {
    // Process decoded audio...
}

---

Python API

AudioDecoder

import avioflow

# Constructor with keyword arguments
decoder = avioflow.AudioDecoder(
    output_sample_rate=16000,    # Optional: target sample rate
    input_format="s16le",        # For streaming: source format
    input_sample_rate=48000,     # For streaming: source rate
    input_channels=2             # For streaming: source channels
)

Methods

Method	Returns	Description
load(source)	Metadata	Load file, URL, pathlib.Path, or bytes-like input
decoder(data)	ndarray	Push bytes-like data and decode (streaming)
read()	ndarray	Decode next frame
get_samples()	ndarray	Decode all available samples
is_finished()	bool	Check if EOF

Metadata

# Quick metadata inspection without full decoding
meta = avioflow.info("audio.mp3")
print(f"Duration: {meta.duration}s")
print(f"Sample Rate: {meta.sample_rate}Hz")
print(f"Codec: {meta.codec}")

# Encoded audio bytes also work
with open("audio.mp3", "rb") as f:
    meta = avioflow.info(f.read())

Examples

File Decoding

decoder = avioflow.AudioDecoder(output_sample_rate=16000)
meta = decoder.load("speech.wav")
samples = decoder.get_samples()      # numpy array (channels, samples)
print(f"Shape: {samples.shape}")     # e.g., (1, 160000)

Streaming Decode

decoder = avioflow.AudioDecoder(
    input_format="s16le",
    input_sample_rate=48000,
    input_channels=2
)

while True:
    data = socket.recv(4096)
    samples = decoder(data)  # Push & get samples in one call
    if samples.size > 0:
        process_audio(samples)

Device Discovery

devices = avioflow.DeviceManager.list_audio_devices()
for dev in devices:
    print(f"{dev.name}: {dev.description}")

Logging

avioflow.set_log_level("debug")  # quiet, error, warning, info, debug, trace

---

Node.js API

Compatibility

Runtime	Version	Support
Node.js	16, 18, 20, 22+	✅ Native (N-API)
Electron	All versions	✅ Supported (requires rebuild)
Architectures	x64	✅ Linux, Windows

Installation

npm install avioflow

ESM Import

import avioflow from 'avioflow';

Module-level Functions

Function	Returns	Description
load(path, options?)	{metadata, samples}	Convenience: Opens, decodes all samples, and returns both in one call.
listAudioDevices()	DeviceInfo[]	List available system audio devices.
setLogLevel(level)	void	Set FFmpeg log level ("quiet", "info", "debug", etc.).

AudioDecoder

// Constructor with options object
const decoder = new avioflow.AudioDecoder({
    outputSampleRate: 16000,    // Optional: target sample rate
    outputNumChannels: 1,       // Optional: target channels
    inputFormat: 's16le',       // For streaming: source format
    inputSampleRate: 48000,     // For streaming: source rate
    inputChannels: 2            // For streaming: source channels
});

Methods

Method	Returns	Description
load(source)	Metadata	Load file, URL, or device name. Returns metadata.
push(buffer)	void	Push raw encoded bytes for streaming.
read()	Float32Array[] | null	Decode next frame. Returns array of channel data.
getSamples()	Float32Array[]	Decode all available samples at once.
isFinished()	boolean	Check if end of stream reached.

Examples

Quick File Loading (Recommended)

// Opens file, resamples to 16kHz mono, and decodes everything
const { metadata, samples } = avioflow.load("audio.mp3", {
    outputSampleRate: 16000,
    outputNumChannels: 1
});

console.log(`Duration: ${metadata.duration}s`);
console.log(`Channels: ${samples.length}, Samples: ${samples[0].length}`);

Batch Decoding with Decoder Instance

const decoder = new avioflow.AudioDecoder({ outputSampleRate: 44100 });
const meta = decoder.load("audio.wav");

// Decodes the entire file into memory
const allSamples = decoder.getSamples();
process(allSamples);

Streaming Decode (Real-time)

const decoder = new avioflow.AudioDecoder({
    inputFormat: 's16le',
    inputSampleRate: 48000,
    inputChannels: 2
});

socket.on('data', (chunk) => {
    decoder.push(chunk);

    // Get all samples decoded from this chunk
    const samples = decoder.getSamples();
    if (samples.length > 0) {
        processAudio(samples);
    }
});

Device Discovery

const devices = avioflow.listAudioDevices();
devices.forEach(dev => {
    console.log(`${dev.isOutput ? 'Output' : 'Input'}: ${dev.name} (${dev.description})`);
});

---

Java API

File Decoding

import io.github.lxp3.avioflow.AudioDecoder;
import io.github.lxp3.avioflow.AudioStreamOptions;

try (AudioDecoder decoder = new AudioDecoder(
        new AudioStreamOptions().outputSampleRate(16000))) {
    decoder.open("audio.mp3");
    float[][] samples = decoder.getSamples();
    System.out.println(samples.length + " channels");
}

Encoding

import io.github.lxp3.avioflow.AudioEncoder;
import io.github.lxp3.avioflow.AudioWriteOptions;

AudioEncoder.saveAudio(
    "out.wav",
    samples,
    new AudioWriteOptions()
        .containerFormat("wav")
        .codecName("pcm_s16le")
        .sampleRate(16000)
);

---

Build from Source

Prerequisites

• CMake 3.20+
• Visual Studio 2022+ (Windows) or GCC 11+ (Linux)
• Python 3.8+ with pybind11 (for Python bindings)
• Node.js 16+ (for Node.js bindings)

C++ & Python Build

./build.sh

This will configure and build the C++ library and Python bindings.

Node.js Build

./build-nodejs.sh

This will build the Node.js bindings using cmake-js and run compatibility tests.

Java Build

./build-java.sh linux-x86_64

This builds the JNI library and creates a platform classifier jar.

---

Supported Formats

AvioFlow supports a wide range of audio formats, codecs, and devices through FFmpeg.

For a complete and detailed list of supported decoders, encoders, and input formats, please refer to the Supported Formats Reference.

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License

MIT License