This document contains the current API restrictions and usage limits for Cloud Speech-to-Text. This page will be updated to reflect any changes to these restrictions and usage limits. We reserve the right to change these limits.
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Content Limits
Content to Speech-to-Text is provided as audio data, either directly within
the content
field of the request or referenced within a Google Cloud Storage
URI in the uri
field of the request. There is a limit of 10 MB on all single
requests sent to the API using local files. In the case of the
Recognize
and
LongRunningRecognize
methods, this limit applies to the size of the request sent. In the case of the
StreamingRecognize
method, the 10 MB limit applies to both the initial StreamingRecognize
request
and the size of each individual message in the stream. Exceeding this limit will
throw an error. There is no size limit on requests sent using audio data stored
in a Google Cloud Storage bucket.
The API contains the following limits on the size of this content (and are subject to change).
Content Limit | Audio Length |
---|---|
Synchronous Requests | ~1 Minute |
Asynchronous Requests | ~480 Minutes* |
Streaming Requests | ~5 Minutes** |
* Audio longer than ~1 minute must
use the uri
field to reference
an audio file in Google Cloud Storage.
** If you need to stream content for more than 5 minutes, see the
endless streaming tutorial.
For StreamingRecognize
requests, audio must be sent at a rate that
approximates real time.
Attempting to process content in excess of these content limits will produce an error. For more information, see Error messages and Troubleshooting.
Within any request, you may also supply a PhraseSet resource containing a list of phrases specific to the request. (A single word counts as a phrase in this context.) The following limits apply to such a context:
Speech Adaptation Limit | Value |
---|---|
Phrases per request | 5000 |
Total characters per request | 100,000 |
Characters per phrase | 100 |
Request Limits
The current API usage limits for Speech-to-Text are as follows (and are subject to change):
Type of Limit | Usage Limit |
---|---|
Recognition Requests per 60 seconds* | 900 |
Adaptation resource requests per 60 seconds* | 10 |
Processing per day | 480 hours of audio |
* Each StreamingRecognize
session is considered a single request even though
it includes multiple frames of StreamingRecognizeRequest
audio within the
stream.
Requests and/or attempts at audio processing in excess of these limits will produce an error. For more information, see Error messages and Troubleshooting.
These limits apply to each Speech-to-Text developer project, and are shared across all applications and IP addresses using a given a developer project.