Overview

The Speech-to-Text API enables easy integration of Google speech recognition technologies into developer applications. The Speech-to-Text API allows you to send audio and receive a text transcription from the service.

What you'll learn

In this lab, you learn how to:

• Create an API key

• Create a Speech-to-Text API request

• Call the Speech-to-Text API

Task 1. Create an API key

Since you'll be using curl to send a request to the Speech-to-Text API, you need to generate an API key to pass in our request URL.

1. To create an API key, click Navigation menu > APIs & services > Credentials.

2. Then click Create credentials.

3. In the drop down menu, select API key.

4. Copy the key you just generated and click Close.

Click Check my progress to verify the objective.

Create an API Key

Check my progress

Now that you have an API key, save it as an environment variable to avoid having to insert the value of your API key in each request.

To perform the next steps, connect using SSH to the instance provisioned for you.

1. In the Navigation menu, select Compute Engine. You should see a linux-instance listed in the VM instances window.

2. Click on the SSH button in line with the linux-instance. You will be brought to an interactive shell.

3. In the command line, enter in the following, replacing <YOUR_API_KEY> with the API key you copied from previously generated:

export API_KEY=<YOUR_API_KEY>

You remain in this SSH session for the rest of the lab.

Task 2. Create your Speech-to-Text API request

Note: You will use a pre-recorded file that's available on Cloud Storage: gs://cloud-samples-tests/speech/brooklyn.flac. Listen to the audio file before sending it to the Speech-to-Text API.

1. Create request.json in the SSH command line. You'll use this to build your request to the Speech-to-Text API:

touch request.json

Copied!content_copy

2. Open the request.json:

nano request.json

Copied!content_copy

Note: You can use your preferred command line editor (nano, vim, emacs) or gcloud. This lab will provide instructions for nano.

3. Add the following to your request.json file, using the uri value of the sample raw audio file:

{
  "config": {
      "encoding":"FLAC",
      "languageCode": "en-US"
  },
  "audio": {
      "uri":"gs://cloud-samples-tests/speech/brooklyn.flac"
  }
}

4. Press control + x and then y to save and click Enter to close the request.json file.

The request body has a config and audio object.

In config, you tell the Speech-to-Text API how to process the request. The encoding parameter tells the API which type of audio encoding you're using while the file is being sent to the API. FLAC is the encoding type for .raw files. Learn more about encoding types in the RecognitionConfig Guide.

There are other parameters you can add to your config object, but encoding is the only required one.

In the audio object, you pass the API the uri of the audio file in Cloud Storage.

Click Check my progress to verify the objective.

Create your Speech-to-Text API request

Check my progress

Now you're ready to call the Speech-to-Text API!

Task 3. Call the Speech-to-Text API

1. Pass your request body, along with the API key environment variable, to the Speech-to-Text API with the following curl command (all in one single command line):

curl -s -X POST -H "Content-Type: application/json" --data-binary @request.json \
"https://speech.googleapis.com/v1/speech:recognize?key=${API_KEY}"

Your response should look something like this:

{
  "results": [
    {
      "alternatives": [
        {
          "transcript": "how old is the Brooklyn Bridge",
          "confidence": 0.98267895
        }
      ]
    }
  ]
}

The transcript value will return the Speech-to-Text API's text transcription of your audio file, and the confidence value indicates how sure the API is that it has accurately transcribed your audio.

You'll notice that you called the syncrecognize method in the request above. The Speech-to-Text API supports both synchronous and asynchronous speech to text transcription. In this example you sent it a complete audio file, but you can also use the syncrecognize method to perform streaming speech to text transcription while the user is still speaking.

You created a Speech-to-Text API request then called the Speech-to-Text API.

2. Run the following command to save the response in a result.json file:

curl -s -X POST -H "Content-Type: application/json" --data-binary @request.json \
"https://speech.googleapis.com/v1/speech:recognize?key=${API_KEY}" > result.json

Click Check my progress to verify the objective.

Call the Speech-to-Text API

---

Solution of Lab

export API_KEY=

curl -LO raw.githubusercontent.com/quiccklabs/Labs_solutions/master/Google%20Cloud%20Speech%20to%20Text%20API%20Qwik%20Start/quicklabgsp119.sh
sudo chmod +x quicklabgsp119.sh
./quicklabgsp119.sh