Use StartSpeechSynthesisTask with an AWS SDK or CLI

To synthesize text

The following start-speech-synthesis-task example synthesizes the text in text_file.txt and stores the resulting MP3 file in the specified bucket.

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

Output:

{
    "SynthesisTask": {
        "TaskId": "70b61c0f-57ce-4715-a247-cae8729dcce9",
        "TaskStatus": "scheduled",
        "OutputUri": "https://s3.us-east-2.amazonaws.com/my-s3-bucket/70b61c0f-57ce-4715-a247-cae8729dcce9.mp3",
        "CreationTime": 1603911042.689,
        "RequestCharacters": 1311,
        "OutputFormat": "mp3",
        "TextType": "text",
        "VoiceId": "Joanna"
    }
}

For more information, see Creating long audio files in the Amazon Polly Developer Guide.

class PollyWrapper:
    """Encapsulates Amazon Polly functions."""

    def __init__(self, polly_client, s3_resource):
        """
        :param polly_client: A Boto3 Amazon Polly client.
        :param s3_resource: A Boto3 Amazon Simple Storage Service (Amazon S3) resource.
        """
        self.polly_client = polly_client
        self.s3_resource = s3_resource
        self.voice_metadata = None


    def do_synthesis_task(
        self,
        text,
        engine,
        voice,
        audio_format,
        s3_bucket,
        lang_code=None,
        include_visemes=False,
        wait_callback=None,
    ):
        """
        Start an asynchronous task to synthesize speech or speech marks, wait for
        the task to complete, retrieve the output from Amazon S3, and return the
        data.

        An asynchronous task is required when the text is too long for near-real time
        synthesis.

        :param text: The text to synthesize.
        :param engine: The kind of engine used. Can be standard or neural.
        :param voice: The ID of the voice to use.
        :param audio_format: The audio format to return for synthesized speech. When
                             speech marks are synthesized, the output format is JSON.
        :param s3_bucket: The name of an existing Amazon S3 bucket that you have
                          write access to. Synthesis output is written to this bucket.
        :param lang_code: The language code of the voice to use. This has an effect
                          only when a bilingual voice is selected.
        :param include_visemes: When True, a second request is made to Amazon Polly
                                to synthesize a list of visemes, using the specified
                                text and voice. A viseme represents the visual position
                                of the face and mouth when saying part of a word.
        :param wait_callback: A callback function that is called periodically during
                              task processing, to give the caller an opportunity to
                              take action, such as to display status.
        :return: The audio stream that contains the synthesized speech and a list
                 of visemes that are associated with the speech audio.
        """
        try:
            kwargs = {
                "Engine": engine,
                "OutputFormat": audio_format,
                "OutputS3BucketName": s3_bucket,
                "Text": text,
                "VoiceId": voice,
            }
            if lang_code is not None:
                kwargs["LanguageCode"] = lang_code
            response = self.polly_client.start_speech_synthesis_task(**kwargs)
            speech_task = response["SynthesisTask"]
            logger.info("Started speech synthesis task %s.", speech_task["TaskId"])

            viseme_task = None
            if include_visemes:
                kwargs["OutputFormat"] = "json"
                kwargs["SpeechMarkTypes"] = ["viseme"]
                response = self.polly_client.start_speech_synthesis_task(**kwargs)
                viseme_task = response["SynthesisTask"]
                logger.info("Started viseme synthesis task %s.", viseme_task["TaskId"])
        except ClientError:
            logger.exception("Couldn't start synthesis task.")
            raise
        else:
            bucket = self.s3_resource.Bucket(s3_bucket)
            audio_stream = self._wait_for_task(
                10, speech_task["TaskId"], "speech", wait_callback, bucket
            )

            visemes = None
            if include_visemes:
                viseme_data = self._wait_for_task(
                    10, viseme_task["TaskId"], "viseme", wait_callback, bucket
                )
                visemes = [
                    json.loads(v) for v in viseme_data.read().decode().split() if v
                ]

            return audio_stream, visemes