Create voice audio files

Cloud Text-to-Speech allows you to convert words and sentences into base64 encoded audio data of natural human speech. You can then convert the audio data into a playable audio file like an MP3 by decoding the base64 data. The Cloud Text-to-Speech API accepts input as raw text or Speech Synthesis Markup Language (SSML).

This document describes how to create an audio file from either text or SSML input using Cloud TTS. You can also review the Cloud TTS basics article if you are unfamiliar with concepts like speech synthesis or SSML.

These samples require that you have installed and initialized the Google Cloud CLI. For information about setting up the gcloud CLI, see Authenticate to Cloud TTS.

Convert text to synthetic voice audio

The following code samples demonstrate how to convert a string into audio data.

You can configure the output of speech synthesis in a variety of ways, including selecting a unique voice or modulating the output in pitch, volume, speaking rate, and sample rate.

Protocol

Refer to the text:synthesize API endpoint for complete details.

To synthesize audio from text, make an HTTP POST request to the text:synthesize endpoint. In the body of your POST request, specify the type of voice to synthesize in the voice configuration section, specify the text to synthesize in the text field of the input section, and specify the type of audio to create in the audioConfig section.

The following code snippet sends a synthesis request to the text:synthesize endpoint and saves the results to a file named synthesize-text.txt. Replace PROJECT_ID with your project ID.

curl -H "Authorization: Bearer $(gcloud auth print-access-token)" \
  -H "x-goog-user-project: <var>PROJECT_ID</var>" \
  -H "Content-Type: application/json; charset=utf-8" \
  --data "{
    'input':{
      'text':'Android is a mobile operating system developed by Google,
         based on the Linux kernel and designed primarily for
         touchscreen mobile devices such as smartphones and tablets.'
    },
    'voice':{
      'languageCode':'en-gb',
      'name':'en-GB-Standard-A',
      'ssmlGender':'FEMALE'
    },
    'audioConfig':{
      'audioEncoding':'MP3'
    }
  }" "https://texttospeech.googleapis.com/v1/text:synthesize" > synthesize-text.txt

The Cloud Text-to-Speech API returns the synthesized audio as base64-encoded data contained in the JSON output. The JSON output in the synthesize-text.txt file looks similar to the following code snippet.

{
  "audioContent": "//NExAASCCIIAAhEAGAAEMW4kAYPnwwIKw/BBTpwTvB+IAxIfghUfW.."
}

To decode the results from the Cloud Text-to-Speech API as an MP3 audio file, run the following command from the same directory as the synthesize-text.txt file.

cat synthesize-text.txt | grep 'audioContent' | \
sed 's|audioContent| |' | tr -d '\n ":{},' > tmp.txt && \
base64 tmp.txt --decode > synthesize-text-audio.mp3 && \
rm tmp.txt

Go

To learn how to install and use the client library for Cloud TTS, see Cloud TTS client libraries. For more information, see the Cloud TTS Go API reference documentation.

To authenticate to Cloud TTS, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.


// SynthesizeText synthesizes plain text and saves the output to outputFile.
func SynthesizeText(w io.Writer, text, outputFile string) error {
	ctx := context.Background()

	client, err := texttospeech.NewClient(ctx)
	if err != nil {
		return err
	}
	defer client.Close()

	req := texttospeechpb.SynthesizeSpeechRequest{
		Input: &texttospeechpb.SynthesisInput{
			InputSource: &texttospeechpb.SynthesisInput_Text{Text: text},
		},
		// Note: the voice can also be specified by name.
		// Names of voices can be retrieved with client.ListVoices().
		Voice: &texttospeechpb.VoiceSelectionParams{
			LanguageCode: "en-US",
			SsmlGender:   texttospeechpb.SsmlVoiceGender_FEMALE,
		},
		AudioConfig: &texttospeechpb.AudioConfig{
			AudioEncoding: texttospeechpb.AudioEncoding_MP3,
		},
	}

	resp, err := client.SynthesizeSpeech(ctx, &req)
	if err != nil {
		return err
	}

	err = os.WriteFile(outputFile, resp.AudioContent, 0644)
	if err != nil {
		return err
	}
	fmt.Fprintf(w, "Audio content written to file: %v\n", outputFile)
	return nil
}

Java

To learn how to install and use the client library for Cloud TTS, see Cloud TTS client libraries. For more information, see the Cloud TTS Java API reference documentation.