NAudio.Alsa 3.0.2-preview.2

NAudio.Alsa

ALSA playback and capture for NAudio on Linux.

This package provides:

Platform

Linux only — the assembly is marked [SupportedOSPlatform("linux")]. It P/Invokes libasound; the runtime SONAME libasound.so.2 is resolved automatically (you do not need the -dev package). Install the ALSA runtime if it is missing:

sudo apt install libasound2t64  # Ubuntu 24.04+ (renamed from libasound2 in the t64 transition)
sudo apt install libasound2     # older Debian/Ubuntu

This package is not pulled in by the NAudio meta-package (there is no net9.0-linux TFM). Reference it explicitly:

dotnet add package NAudio.Alsa

Supported input formats

AlsaOut plays any IWaveProvider, so it is format-agnostic — what you can play depends on which decoder you feed it. MediaFoundationReader and the bundled Mp3FileReader / AudioFileReader are Windows-only, but the cross-platform NAudio.SoundFile package (libsndfile) decodes the compressed/free codecs on Linux:

SoundFileReader is the cross-platform MediaFoundationReader-style decoder (it is a WaveStream / ISampleProvider); add the NAudio.SoundFile package and a system libsndfile to play FLAC/Ogg/Opus/ MP3 through AlsaOut. NAudio.SoundFile also encodes those formats, so it pairs with AlsaIn to capture straight to FLAC/Ogg/Opus.

Play a WAV file

using NAudio.Wave;
using NAudio.Wave.Alsa;

using (var audioFile = new WaveFileReader("test.wav"))
using (var outputDevice = new AlsaOut())          // default device
{
    outputDevice.Init(audioFile);
    outputDevice.Play();
    while (outputDevice.PlaybackState == PlaybackState.Playing)
        Thread.Sleep(200);
}

Play FLAC/Ogg/Opus/MP3 with SoundFileReader (cross-platform, needs a system libsndfile — dotnet add package NAudio.SoundFile):

using NAudio.SoundFile;

using var audioFile = new SoundFileReader("test.flac");
using var output = new AlsaOut();
output.Init(audioFile);
output.Play();

Or play MP3 by wiring a managed decompressor into Mp3FileReaderBase (no native dependency):

// using NLayer.NAudioSupport;  // dotnet add package NLayer.NAudioSupport
using var mp3 = new Mp3FileReaderBase("test.mp3",
    waveFormat => new Mp3FrameDecompressor(waveFormat));
using var output = new AlsaOut();
output.Init(mp3);
output.Play();

Record to a WAV file

using NAudio.Wave;
using NAudio.Wave.Alsa;

using var writer = new WaveFileWriter("captured.wav", new WaveFormat(44100, 16, 2));
using var input = new AlsaIn { WaveFormat = writer.WaveFormat };
input.DataAvailable += (s, a) => writer.Write(a.Buffer, 0, a.BytesRecorded);
input.StartRecording();
Thread.Sleep(5000);
input.StopRecording();

Swap WaveFileWriter for NAudio.SoundFile's SoundFileWriter to capture straight to FLAC/Ogg-Vorbis/Opus instead of WAV.

Enumerate devices

foreach (var d in AlsaDeviceEnumerator.GetPlaybackDevices())
    Console.WriteLine($"{d.Name} - {d.Description}");

AlsaDeviceInfo.Name is passed straight to new AlsaOut(name) / new AlsaIn(name).

Notes

• Output is taken through a SampleChannel, so AlsaOut.Volume is a real software gain and mono sources are handled. The device format is negotiated as IEEE float, else 16-bit, else 24-bit PCM.
• Pause() uses hardware pause where the driver supports it, otherwise it drops and re-prepares the stream on resume.
• A dedicated streaming thread does blocking I/O and recovers from xruns; it is always joined before the device handle is closed.

Documentation

See the NAudio documentation site for tutorials and the full API reference, or the GitHub repository for source, issues and demos.

License

MIT.