Transcribe audio from streaming input

This section demonstrates how to transcribe streaming audio, like the input from a microphone, to text.

Streaming speech recognition allows you to stream audio to Speech-to-Text and receive a stream speech recognition results in real time as the audio is processed. See also the audio limits for streaming speech recognition requests. Streaming speech recognition is available through gRPC only.

Before you begin

  1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get 300ドル in free credits to run, test, and deploy workloads.

  2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

    Go to project selector

  3. Verify that billing is enabled for your Google Cloud project.

  4. Enable the Speech-to-Text APIs.

    Roles required to enable APIs

    To enable APIs, you need the Service Usage Admin IAM role (roles/serviceusage.serviceUsageAdmin), which contains the serviceusage.services.enable permission. Learn how to grant roles.

    Enable the APIs

  5. Make sure that you have the following role or roles on the project: Cloud Speech Administrator

    Check for the roles

    1. In the Google Cloud console, go to the IAM page.

      Go to IAM
    2. Select the project.

    3. In the Principal column, find all rows that identify you or a group that you're included in. To learn which groups you're included in, contact your administrator.

    4. For all rows that specify or include you, check the Role column to see whether the list of roles includes the required roles.

    Grant the roles

    1. In the Google Cloud console, go to the IAM page.

      Go to IAM
    2. Select the project.
    3. Click Grant access.

    4. In the New principals field, enter your user identifier. This is typically the email address for a Google Account.

    5. In the Select a role list, select a role.
    6. To grant additional roles, click Add another role and add each additional role.
    7. Click Save.

  6. Install the Google Cloud CLI.

  7. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  8. To initialize the gcloud CLI, run the following command: 

    gcloudinit

  9. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

    Go to project selector

  10. Verify that billing is enabled for your Google Cloud project.

  11. Enable the Speech-to-Text APIs.

    Roles required to enable APIs

    To enable APIs, you need the Service Usage Admin IAM role (roles/serviceusage.serviceUsageAdmin), which contains the serviceusage.services.enable permission. Learn how to grant roles.

    Enable the APIs

  12. Make sure that you have the following role or roles on the project: Cloud Speech Administrator

    Check for the roles

    1. In the Google Cloud console, go to the IAM page.

      Go to IAM
    2. Select the project.

    3. In the Principal column, find all rows that identify you or a group that you're included in. To learn which groups you're included in, contact your administrator.

    4. For all rows that specify or include you, check the Role column to see whether the list of roles includes the required roles.

    Grant the roles

    1. In the Google Cloud console, go to the IAM page.

      Go to IAM
    2. Select the project.
    3. Click Grant access.

    4. In the New principals field, enter your user identifier. This is typically the email address for a Google Account.

    5. In the Select a role list, select a role.
    6. To grant additional roles, click Add another role and add each additional role.
    7. Click Save.

  13. Install the Google Cloud CLI.

  14. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  15. To initialize the gcloud CLI, run the following command: 

    gcloudinit

    16. Client libraries can use Application Default Credentials to easily authenticate with Google APIs and send requests to those APIs. With Application Default Credentials, you can test your application locally and deploy it without changing the underlying code. For more information, see Authenticate for using client libraries.

  16. If you're using a local shell, then create local authentication credentials for your user account: 

    gcloudauthapplication-defaultlogin

    You don't need to do this if you're using Cloud Shell.

    If an authentication error is returned, and you are using an external identity provider (IdP), confirm that you have signed in to the gcloud CLI with your federated identity.

Also ensure you have installed the client library.

Perform streaming speech recognition on a local file

Below is an example of performing streaming speech recognition on a local audio file. There is a 25 KB limit on audio sent in the requests of a stream. This limit applies to to both the initial StreamingRecognize request and the size of each individual message in the stream. Exceeding this limit will throw an error.

Python

importos
fromgoogle.cloud.speech_v2import SpeechClient
fromgoogle.cloud.speech_v2.typesimport cloud_speech as cloud_speech_types
PROJECT_ID = os.getenv("GOOGLE_CLOUD_PROJECT")
deftranscribe_streaming_v2(
 stream_file: str,
) -> cloud_speech_types.StreamingRecognizeResponse:
"""Transcribes audio from an audio file stream using Google Cloud Speech-to-Text API.
 Args:
 stream_file (str): Path to the local audio file to be transcribed.
 Example: "resources/audio.wav"
 Returns:
 list[cloud_speech_types.StreamingRecognizeResponse]: A list of objects.
 Each response includes the transcription results for the corresponding audio segment.
 """
 # Instantiates a client
 client = SpeechClient()
 # Reads a file as bytes
 with open(stream_file, "rb") as f:
 audio_content = f.read()
 # In practice, stream should be a generator yielding chunks of audio data
 chunk_length = len(audio_content) // 5
 stream = [
 audio_content[start : start + chunk_length]
 for start in range(0, len(audio_content), chunk_length)
 ]
 audio_requests = (
 cloud_speech_types.StreamingRecognizeRequest(audio=audio) for audio in stream
 )
 recognition_config = cloud_speech_types.RecognitionConfig(
 auto_decoding_config=cloud_speech_types.AutoDetectDecodingConfig(),
 language_codes=["en-US"],
 model="chirp_3",
 )
 streaming_config = cloud_speech_types.StreamingRecognitionConfig(
 config=recognition_config
 )
 config_request = cloud_speech_types.StreamingRecognizeRequest(
 recognizer=f"projects/{PROJECT_ID}/locations/global/recognizers/_",
 streaming_config=streaming_config,
 )
 defrequests(config: cloud_speech_types.RecognitionConfig, audio: list) -> list:
 yield config
 yield from audio
 # Transcribes the audio into text
 responses_iterator = client.streaming_recognize(
 requests=requests(config_request, audio_requests)
 )
 responses = []
 for response in responses_iterator:
 responses.append(response)
 for result in response.results:
 print(f"Transcript: {result.alternatives[0].transcript}")
 return responses

While you can stream a local audio file to the Speech-to-Text API, it is recommended that you perform synchronous audio recognition.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used on this page, follow these steps.

  1. Optional: Revoke the authentication credentials that you created, and delete the local credential file. 

    gcloudauthapplication-defaultrevoke

  2. Optional: Revoke credentials from the gcloud CLI. 

    gcloudauthrevoke

Console

  • In the Google Cloud console, go to the Manage resources page.

    Go to Manage resources

  • In the project list, select the project that you want to delete, and then click Delete.
  • In the dialog, type the project ID, and then click Shut down to delete the project.

    • gcloud

  • In the Google Cloud console, go to the Manage resources page.

    Go to Manage resources

  • In the project list, select the project that you want to delete, and then click Delete.
  • In the dialog, type the project ID, and then click Shut down to delete the project.

    • What's next

    Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

    Last updated 2025年11月04日 UTC.