Synthesizing speech using AWS CLI commands

To synthesize speech use the `synthesize-speech` command.
aws polly synthesize-speech \
    --output-format mp3 \
    --voice-id Joanna \
    --text 'Hello, This is a sample text recorded using AWS Polly.' \
    hello.mp3

This command generates a file named hello.mp3. In addition to the MP3 file, the operation sends the following output to the console.

The –voice-id is the voice that should be used in the audio file. There are many voices available in AWS Polly for each of the language. You can get a list of voice id using the aws polly synthesize-speech help command and look in the –voice-id section or the describe-voices command.

To generate a speech in another language use the –language-code option. This command produces audio in Indian English with the voice id as Aditi. You can get the list of the language codes with the help command.

aws polly synthesize-speech \
    --output-format mp3 \
    --voice-id Aditi \
    --text 'Hello, This is a sample text recorded using AWS Polly.' \
    --language-code en-IN \
    hello2.mp3

Find the voice ids related to a specific language. This command prints all the available voices for Indian English.

aws polly describe-voices --language-code en-IN

AWS Polly has three kinds of text to speech engines: standard, neural and long-form. Use the –engine option to configure the engine used to produce speech. This command uses the neural engine with Kajal voice id to produce speech.

aws polly synthesize-speech \
    --output-format mp3 \
    --voice-id Kajal \
    --engine neural \
    --text 'Hello, This is a sample text recorded using AWS Polly.' \
    --language-code en-IN \
    hello3.mp3

Not all voices supports the neural engine. If you use an unsupported voice id for neural engine then it will cause an error.

The synthesize-speech command has many options available that supports multiple languages, file formats, voices, engines, SSML etc. which can be found in the AWS documentation or aws polly synthesize-speech help command.

Speech synthesis tasks

A speech synthesis task is an asynchronous operation that allows you to create speech synthesis tasks. These are suitable for long texts which can take a while to produce the results. The generated audio files are stored in an S3 bucket. Once the task is created you will get a SpeechSynthesisTask object, which includes id of the task and other details. This object is available for 72 hours after starting the task.

This command starts a speech synthesis task that gets its input from the input.txt (input.txt should be in the same directory) file and stores the file in `my-s3-bucket`. (Make sure you have created a bucket and use that bucket name in –output-s3-bucket-name option.)

aws polly start-speech-synthesis-task \
              --output-format mp3 \
              --output-s3-bucket-name my-s3-bucket \
              --text  file://input.txt \
              --voice-id Joanna

Output:

• TaskId: the id of the task you just created.
• TaskStatus: Current status of the task.
• OutputUri: Pathway of the output speech file.
• CreationTime: Timestamp for the time the synthesis task was started.
• RequestCharacters: Number of billable characters synthesized.
• OutputFormat: Format in which the output file will be encoded.
• TextType: Specifies whether the input text is plain text or SSML.
• VoiceId: Voice ID used for the synthesis.

To list all the speech synthesis tasks use the `list-speech-synthesis-tasks` command.

aws polly list-speech-synthesis-tasks

Output:

To get a specific speech synthesis task based on its TaskId use the `get-speech-synthesis-task` command.

aws polly get-speech-synthesis-task \
        --task-id <Enter SPEECH_SYNTHESIS_TASK_ID here>

Output:

Amazon Polly is a managed service provided by AWS that makes it easy to synthesize speech from text. In this article, we will learn how to use Polly through the AWS CLI. We will learn how to use all the commands available in Polly along with some examples.