This project requires the Ngrok library to be installed for creating a publicly-accessible webhook URL that forwards to your local machine. You'll also need to ensure you have the dotnet library installed, or another version of the .NET 8 CLI available to build and run this project.
To start, you'll need to create a publicly-accessible Webhook URL that our API can reach. Normally this would be your own Webhook server, but for the purposes of this demo, we're using Ngrok to set up forwarding to our localhost domain. Once you've installed ngrok, simply run ngrok http 8000 to start up an Ngrok server that points to your machine on port 8000.
You can verify that this is the case by looking at the "Forwarding" section of the output in your terminal window. You should see http://localhost:8000 on the right side of the arrow, while the URL on the left of the arrow is the URL you're going to need for later. Copy that now and have it ready to use.
Now you'll need to replace the placeholder variables that we've configured for this project. Under WebhookReceiver/Controllers/WebhookController.cs, you'll want to replace the "API_KEY_HERE" string with your AssemblyAI API key, which can be located on your account dashboard.
Next you'll want to replace the 3 variables API_KEY, FILE_NAME, and WEBHOOK_URL under TranscriptionSubmitter/Program.cs with your AssemblyAI API key, audio file name/path, and Ngrok URL from earlier, respectively. Make sure to retain the /api/webhook ending to your Ngrok URL, as otherwise you'll encounter a 404 error when Webhook responses are received.
For instance, your Ngrok URL should be something like https://09e2-2600-6c52-427f-a41f-1923-ce-c982-3f01.ngrok-free.app/api/webhook. Now you're ready to run these two programs!
In another terminal window (ensure that your Ngrok program from before is still running), navigate into the TranscriptionSubmitter folder. Then run dotnet run. Now you'll see in the terminal output that your Webhook server is listening on port 8000, which is where your Webhook calls will be forwarded to.
In a third terminal window, navigate into the WebhookReceiver folder. Then run dotnet run. This will submit the file you specified under FILE_NAME to our API using your Ngrok URL as your Webhook URL. You'll get back a transcript ID to confirm that your file was successfully uploaded and provided to our API.
After the file finishes processing, your Webhook server will be called with a payload containing the status of the transcript. If it's completed, we'll make a GET request to fetch the full transcript text and write it to a file named [id].txt. If it's error, we'll log an error message to the terminal letting you know that the transcript failed.
Congrats! You've now transcribed a file with the AssemblyAI API using Webhooks in C#.
If anything happens to go wrong, or you have any questions on this project, please feel free to reach out to [email protected]. Happy coding!