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

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 in free credits to run, test, and deploy workloads.

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

Go to project selector

Verify that billing is enabled for your Google Cloud project .

Enable the Speech-to-Text APIs.

Enable the APIs

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 person_add 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 Add another role and add each additional role.
7. Click Save .

Install the Google Cloud CLI.

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

To initialize the gcloud CLI, run the following command:

gcloud  
init

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

Go to project selector

Verify that billing is enabled for your Google Cloud project .

Enable the Speech-to-Text APIs.

Enable the APIs

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 person_add 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 Add another role and add each additional role.
7. Click Save .

Install the Google Cloud CLI.

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

To initialize the gcloud CLI, run the following command:

gcloud  
init

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 .

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

   gcloud  
   auth  
   application-default  
   login

   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.

  import 
  
 os 
 from 
  
 google.cloud.speech_v2 
  
 import 
 SpeechClient 
 from 
  
 google.cloud.speech_v2.types 
  
 import 
 cloud_speech 
 as 
 cloud_speech_types 
 PROJECT_ID 
 = 
 os 
 . 
 getenv 
 ( 
 "GOOGLE_CLOUD_PROJECT" 
 ) 
 def 
  
 transcribe_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 
 = 
 "long" 
 , 
 ) 
 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 
 , 
 ) 
 def 
  
 requests 
 ( 
 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.

   gcloud  
   auth  
   application-default  
   revoke

2. Optional: Revoke credentials from the gcloud CLI.

   gcloud  
   auth  
   revoke

What's next

• See the reference documentation for streaming recognition.
• Practice transcribing short audio files .
• Learn how to transcribe long audio files .
• Transcribe audio files using Chirp .
• For best performance, accuracy, and other tips, see the best practices documentation.