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Transcribe Live

Connect to the AssemblyAI v3 real-time streaming API for live speech-to-text transcription.

This example assumes using AssemblyAI; is in scope and apiKey contains your AssemblyAI API key.

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var apiKey =
    Environment.GetEnvironmentVariable("ASSEMBLYAI_API_KEY") is { Length: > 0 } apiKeyValue
        ? apiKeyValue
        : throw new AssertInconclusiveException("ASSEMBLYAI_API_KEY environment variable is not found.");

// Create the realtime client and connect.
using var client = new AssemblyAIRealtimeClient();
await client.ConnectAsync(
    new Uri($"wss://streaming.assemblyai.com/v3/ws?api_key={apiKey}"));

// Receive the session started event.
using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
var receivedSessionBegins = false;

await foreach (var serverEvent in client.ReceiveUpdatesAsync(cts.Token))
{
    if (serverEvent.IsBegin)
    {
        receivedSessionBegins = true;
        Console.WriteLine($"Session started: {serverEvent.Begin?.Id}");
        Console.WriteLine($"Expires at: {serverEvent.Begin?.ExpiresAt}");

        // After session starts, send audio data.
        // In a real application, you would stream microphone PCM16 audio:
        // await client.SendAsync(audioBytes, WebSocketMessageType.Binary, true, cts.Token);

        // Update configuration for turn detection sensitivity.
        await client.SendUpdateConfigurationAsync(new UpdateConfigurationPayload
        {
            EndOfTurnConfidenceThreshold = 0.5,
            MaxTurnSilence = 2000,
        });

        // For this example, manually force an endpoint to get results.
        await client.SendForceEndpointAsync(new ForceEndpointPayload());
    }
    else if (serverEvent.IsTurn)
    {
        var turn = serverEvent.Turn!;
        Console.WriteLine($"Turn {turn.TurnOrder}: {turn.Transcript}");
        Console.WriteLine($"  End of turn: {turn.EndOfTurn}");
        Console.WriteLine($"  Confidence: {turn.EndOfTurnConfidence}");

        if (turn.EndOfTurn == true)
        {
            break;
        }
    }
    else if (serverEvent.IsTermination)
    {
        var termination = serverEvent.Termination!;
        Console.WriteLine($"Session terminated. Audio: {termination.AudioDurationSeconds}s, Session: {termination.SessionDurationSeconds}s");
        break;
    }
}

// Gracefully terminate the session.
await client.SendSessionTerminationAsync(new SessionTerminationPayload());