Read audio metadata

using OneAudio;
using OneAudio.Flac;
using OneAudio.Vorbis;
 
// Format, length and tags of every file in the folder, without decoding
// the audio.
foreach (string path in Directory.GetFiles(".").Order())
{
    try
    {
        using IAudioDecoder d = Audio.Open(path);
        AudioFormat f = d.Format;
        string length = d.LengthFrames >= 0
            ? $"{d.LengthFrames / (double)f.SampleRate:F2} s"
            : "unknown length";
        string name = Path.GetFileName(path);
        Console.WriteLine($"{name,-19}{d.GetType().Name,-18}{f.SampleRate,6} Hz " +
                          $"{f.Channels} ch  {f.NativeType,-12}{length}");
 
        IReadOnlyList<string>? tags = d switch
        {
            VorbisDecoder v => v.Comments,
            FlacDecoder fl => fl.Comments,
            _ => null,                  // Opus and MP3 tags aren't exposed in 1.2.1
        };
        foreach (string tag in tags ?? [])
        {
            int eq = tag.IndexOf('=');  // NAME=value, in any case
            Console.WriteLine($"{"",19}{tag[..eq].ToUpperInvariant()}: {tag[(eq + 1)..]}");
        }
    }
    catch (UnsupportedAudioFormatException)
    {
        Console.WriteLine($"{Path.GetFileName(path),-19}not an audio format oneaudio reads");
    }
}

chained.ogg        VorbisDecoder      44100 Hz 2 ch  Lossy       38.03 s
                   ENCODER: Lavc62.11.100 libvorbis
                   ARTIST: Test signal
                   TITLE: Four chords
game-mix.wav       WavDecoder         48000 Hz 2 ch  PcmSigned16 16.00 s
hit.wav            WavDecoder         48000 Hz 1 ch  PcmSigned16 0.40 s
music-noheader.mp3 Mp3Decoder         44100 Hz 2 ch  Lossy       32.03 s
music.flac         FlacDecoder        44100 Hz 2 ch  PcmSigned16 32.00 s
                   DATE: 2026
                   TITLE: Four chords
                   ARTIST: Test signal
                   ENCODER: Lavf62.3.100
music.mp3          Mp3Decoder         44100 Hz 2 ch  Lossy       32.00 s
music.ogg          VorbisDecoder      44100 Hz 2 ch  Lossy       32.00 s
                   ENCODER: Lavc62.11.100 libvorbis
                   ARTIST: Test signal
                   TITLE: Four chords
music.opus         OpusStreamDecoder  48000 Hz 2 ch  Lossy       32.00 s
music.wav          WavDecoder         44100 Hz 2 ch  PcmSigned16 32.00 s
voice.wav          WavDecoder         16000 Hz 1 ch  PcmSigned16 6.03 s