NAudio.SoundFile

Cross-platform audio file reading and writing for NAudio, backed by libsndfile.

This is the first cross-platform FLAC/Vorbis/Opus encoder in NAudio, and on Linux/macOS the first general-purpose decoder (there is no Media Foundation off Windows).

Platform

Truly cross-platform — net9.0, no [SupportedOSPlatform]. It P/Invokes a system libsndfile, resolved automatically per OS (libsndfile.so.1 / libsndfile.1.dylib / sndfile.dll / libsndfile-1.dll). You must provide it:

sudo apt install libsndfile1     # Debian/Ubuntu
brew install libsndfile          # macOS
vcpkg install libsndfile         # Windows (or the official binaries)

Not pulled in by the NAudio meta-package — reference it explicitly:

dotnet add package NAudio.SoundFile

Supported formats

Codec availability depends on how libsndfile was built — query it:

foreach (var f in SoundFileCapabilities.GetSupportedMajorFormats())
    Console.WriteLine(f);
bool canFlac = SoundFileCapabilities.IsFormatSupported(SoundFileMajorFormat.Flac);

AAC / M4A / ALAC / WMA are out of scope (the MPEG-4 family is FFmpeg territory).

Read any file

SoundFileReader decodes to 32-bit float, so it is both a WaveStream and an ISampleProvider:

using NAudio.SoundFile;
using NAudio.Wave;

using var reader = new SoundFileReader("song.flac");
Console.WriteLine($"{reader.WaveFormat} {reader.TotalTime}");
// feed it into any NAudio output, mixer or sample pipeline

Write FLAC / Ogg / Opus

using (var source = new SoundFileReader("in.wav"))
    SoundFileWriter.CreateSoundFile("out.flac", source,
        SoundFileMajorFormat.Flac,
        new SoundFileWriterOptions { CompressionLevel = 0.8 });

// Ogg Vorbis at VBR quality 0.6, with tags
using (var source = new SoundFileReader("in.wav"))
    SoundFileWriter.CreateSoundFile("out.ogg", source,
        SoundFileMajorFormat.OggVorbis,
        new SoundFileWriterOptions
        {
            VbrQuality = 0.6,
            Tags = new SoundFileTags { Title = "Demo", Artist = "NAudio" }
        });

Read embedded metadata back:

using var reader = new SoundFileReader("song.flac");
Console.WriteLine($"{reader.Tags.Artist} – {reader.Tags.Title}");
Console.WriteLine(SoundFileCapabilities.LibraryVersion);

The output format is also inferred from the extension:

SoundFileWriter.CreateSoundFile("out.flac", source); // → FLAC

Streams

Both ends work over a System.IO.Stream (via libsndfile virtual I/O):

using var ms = new MemoryStream();
SoundFileWriter.WriteSoundFileToStream(ms, source, SoundFileMajorFormat.OggVorbis, null);
ms.Position = 0;
using var reader = new SoundFileReader(ms);   // stream not disposed by the reader

FLAC/Ogg/Opus/MP3 stream fine to a forward-only target; WAV/AIFF back-patch their header at close and require a seekable stream (the writer throws early if you pair a non-seekable stream with such a format).

Notes

• The writer accepts 16-bit PCM or 32-bit IEEE float input — the two container types NAudio pipelines naturally produce. Convert other formats with SampleToWaveProvider16 or .ToSampleProvider() first.
• AOT-compatible: source-generated [LibraryImport], SafeHandle lifetime, and [UnmanagedCallersOnly] virtual-I/O callbacks.
• The wrapper is MIT; libsndfile itself is LGPL-2.1+ and supplied by the user as a system library (no binary is shipped) — the same model as NAudio.Alsa.

Tutorial

For a worked walkthrough (reading, encoding, format conversion, streams, tags, capability detection) see Cross-platform audio file reading and writing with NAudio.SoundFile.

Documentation

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

License

MIT.