Program.cs

using System.Diagnostics;
using AssemblyAI.Realtime;

// Set up the cancellation token, so we can stop the program with Ctrl+C
var cts = new CancellationTokenSource();
var ct = cts.Token;
Console.CancelKeyPress += (sender, e) => cts.Cancel();

// Set up the realtime transcriber
await using var transcriber = new RealtimeTranscriber(new RealtimeTranscriberOptions
{
    ApiKey = Environment.GetEnvironmentVariable("ASSEMBLYAI_API_KEY"),
    SampleRate = 16_000
});

transcriber.PartialTranscriptReceived.Subscribe(transcript =>
{
    if (transcript.Text == "") return;
    Console.WriteLine($"Partial transcript: {transcript.Text}");
});
transcriber.FinalTranscriptReceived.Subscribe(transcript =>
{
    Console.WriteLine($"Final transcript: {transcript.Text}");
});

await transcriber.ConnectAsync();

var soxArguments = string.Join(' ', [
    "--default-device",
    "--no-show-progress",
    "--rate 16000",
    "--channels 1",
    "--encoding signed-integer",
    "--bits 16",
    "--type wav",
    "-" // pipe
]);
Console.WriteLine($"sox {soxArguments}");
using var soxProcess = new Process
{
    StartInfo = new ProcessStartInfo
    {
        FileName = "sox",
        Arguments = soxArguments,
        RedirectStandardOutput = true,
        RedirectStandardError = true,
        UseShellExecute = false,
        CreateNoWindow = true
    }
};

soxProcess.Start();
soxProcess.BeginErrorReadLine();
var soxOutputStream = soxProcess.StandardOutput.BaseStream;
var buffer = new Memory<byte>(new byte[4096]);
while (await soxOutputStream.ReadAsync(buffer, ct) > 0)
{
    if (ct.IsCancellationRequested) break;
    await transcriber.SendAudioAsync(buffer);
}

soxProcess.Kill();
await transcriber.CloseAsync();