Speech Recognition with Keyword Spotting in C#

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This sample demonstrates how to use the Azure Cognitive Services Speech SDK to recognize speech with keyword spotting in a C# console application.

Program.cs

How to generate this sample

Command

ai dev new speech-to-text-with-keyword --csharp

Output

AI - Azure AI CLI, Version 1.0.0
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This PUBLIC PREVIEW version may change at any time.
See: https://aka.ms/azure-ai-cli-public-preview

Generating 'speech-to-text-with-keyword' in 'speech-to-text-with-keyword-cs' (3 files)...

Program.cs

Generating 'speech-to-text-with-keyword' in 'speech-to-text-with-keyword-cs' (1 files)... DONE!

Program.cs

STEP 1: Read the connection and configuration details from environment variables.

Program.cs

var speechKey = Environment.GetEnvironmentVariable("AZURE_AI_SPEECH_KEY") ?? "<insert your Speech Service API key here>";
var speechRegion = Environment.GetEnvironmentVariable("AZURE_AI_SPEECH_REGION") ?? "<insert your Speech Service region here>";
var speechLanguage = "en-US"; // BCP-47 language code
var inputFileName = args.Length == 1 ? args[0] : null;
var keywordFileName = "keyword.table";

STEP 2: Check if the input file and keyword file exist.

Program.cs

if (inputFileName != null && !File.Exists(inputFileName))
{
    Console.WriteLine($"ERROR: Cannot find audio input file: {inputFileName}");
    return 1;
}

if (!File.Exists(keywordFileName))
{
    Console.WriteLine($"ERROR: Cannot find keyword file: {keywordFileName}");
    return 1;
}

STEP 3: Create instances of a speech config, source language config, and audio config.

Program.cs

var config = SpeechConfig.FromSubscription(speechKey, speechRegion);
var sourceLanguageConfig = SourceLanguageConfig.FromLanguage(speechLanguage);
var audioConfig = inputFileName != null
    ? AudioConfig.FromWavFileInput(inputFileName)
    : AudioConfig.FromDefaultMicrophoneInput();

STEP 4: Create the speech recognizer and subscribe to events.

Program.cs

using (var recognizer = new SpeechRecognizer(config, sourceLanguageConfig, audioConfig))
{
    recognizer.Recognizing += (s, e) => HandleRecognizingEvent(e);
    recognizer.Recognized += (s, e) => HandleRecognizedEvent(e);

    var sessionStoppedNoError = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
    recognizer.SessionStarted += (s, e) => HandleSessionStartedEvent(e);
    recognizer.SessionStopped += (s, e) => HandleSessionStoppedEvent(e);
    recognizer.Canceled += (s, e) => HandleCanceledEvent(e, sessionStoppedNoError);

    Task.Run(() =>
    {
        while (Console.ReadKey().Key != ConsoleKey.Enter) { }
        recognizer.StopContinuousRecognitionAsync();
    });

    var keywordModel = KeywordRecognitionModel.FromFile(keywordFileName);

    await recognizer.StartKeywordRecognitionAsync(keywordModel);
    Console.WriteLine("Listening for keyword; press ENTER to stop ...\n");

    return await sessionStoppedNoError.Task ? 0 : 1;
}

STEP 5: Define the event handlers.

Program.cs

private static void HandleRecognizingEvent(SpeechRecognitionEventArgs e)
{
    Console.WriteLine($"RECOGNIZING: {e.Result.Text}");
}

private static void HandleRecognizedEvent(SpeechRecognitionEventArgs e)
{
    if (e.Result.Reason == ResultReason.RecognizedKeyword && !string.IsNullOrEmpty(e.Result.Text))
    {
        Console.WriteLine($"RECOGNIZED: {e.Result.Text}\n");
    }
    else if (e.Result.Reason == ResultReason.RecognizedSpeech && !string.IsNullOrEmpty(e.Result.Text))
    {
        Console.WriteLine($"RECOGNIZED: {e.Result.Text}\n");
    }
    else if (e.Result.Reason == ResultReason.NoMatch)
    {
        Console.WriteLine($"NOMATCH: Speech could not be recognized.\n");
    }
}

private static void HandleSessionStartedEvent(SessionEventArgs e)
{
    Console.WriteLine($"SESSION STARTED: {e.SessionId}.\n");
}

private static void HandleSessionStoppedEvent(SessionEventArgs e)
{
    Console.WriteLine($"SESSION STOPPED: {e.SessionId}.");
}

private static void HandleCanceledEvent(SpeechRecognitionCanceledEventArgs e, TaskCompletionSource<bool> sessionStoppedNoError)
{
    Console.WriteLine($"CANCELED: Reason={e.Reason}");

    if (e.Reason == CancellationReason.EndOfStream)
    {
        Console.WriteLine($"CANCELED: End of the audio stream was reached.");
    }
    else if (e.Reason == CancellationReason.Error)
    {
        Console.WriteLine($"CANCELED: ErrorCode={e.ErrorCode}");
        Console.WriteLine($"CANCELED: ErrorDetails={e.ErrorDetails}");
        Console.WriteLine($"CANCELED: Did you update the subscription info?");
    }

    sessionStoppedNoError.TrySetResult(e.Reason != CancellationReason.Error);
}