Cheetah Binding for Web
Cheetah Speech-to-Text Engine
Made in Vancouver, Canada by Picovoice
Cheetah is an on-device streaming speech-to-text engine. Cheetah is:
- Private; All voice processing runs locally.
- Accurate
- Compact and Computationally-Efficient
- Cross-Platform:
- Linux (x86_64), macOS (x86_64, arm64), and Windows (x86_64)
- Android and iOS
- Chrome, Safari, Firefox, and Edge
- Raspberry Pi (4, 3) and NVIDIA Jetson Nano
Compatibility
- Chrome / Edge
- Firefox
- Safari
Restrictions
IndexedDB is required to use Cheetah
in a worker thread. Browsers without IndexedDB support
(i.e. Firefox Incognito Mode) should use Cheetah
in the main thread.
Installation
Package
Using Yarn
:
yarn add @picovoice/cheetah-web
or using npm
:
npm install --save @picovoice/cheetah-web
AccessKey
Cheetah requires a valid Picovoice AccessKey
at initialization. AccessKey
acts as your credentials when using Cheetah SDKs.
You can get your AccessKey
for free. Make sure to keep your AccessKey
secret.
Signup or Login to Picovoice Console to get your AccessKey
.
Usage
Create a model in Picovoice Console or use the default model.
For the web packages, there are two methods to initialize Cheetah.
Public Directory
NOTE: Due to modern browser limitations of using a file URL, this method does not work if used without hosting a server.
This method fetches the model file from the public directory and feeds it to Cheetah. Copy the model file into the public directory:
cp ${CHEETAH_MODEL_FILE} ${PATH_TO_PUBLIC_DIRECTORY}
Base64
NOTE: This method works without hosting a server, but increases the size of the model file roughly by 33%.
This method uses a base64 string of the model file and feeds it to Cheetah. Use the built-in script pvbase64
to
base64 your model file:
npx pvbase64 -i ${CHEETAH_MODEL_FILE} -o ${OUTPUT_DIRECTORY}/${MODEL_NAME}.js
The output will be a js file which you can import into any file of your project. For detailed information about pvbase64
,
run:
npx pvbase64 -h
Cheetah Model
Cheetah saves and caches your model file in IndexedDB to be used by WebAssembly. Use a different customWritePath
variable
to hold multiple models and set the forceWrite
value to true to force re-save a model file.
Either base64
or publicPath
must be set to instantiate Cheetah. If both are set, Cheetah will use the base64
model.
const cheetahModel = {
publicPath: ${MODEL_RELATIVE_PATH},
base64: ${MODEL_BASE64_STRING},
customWritePath: "cheetah_model",
forceWrite: false,
version: 1,
}
Init options
Set endpointDurationSec
value to 0 if you do not wish to detect endpoint (moment of silence). Set enableAutomaticPunctuation
to
true to enable punctuation in transcript. Set processErrorCallback
to handle errors if an error occurs while transcribing.
const options = {
endpointDurationSec: 1.0,
enableAutomaticPunctuation: false,
processErrorCallback: (error) => {}
}
Initialize Cheetah
Create a transcriptCallback
function to get the streaming results
from the engine:
let transcript = "";
function transcriptCallback(cheetahTranscript: CheetahTranscript) {
transcript += cheetahTranscript.transcript;
if (cheetahTranscript.isEndpoint) {
transcript += ". ";
}
if (cheetahTranscript.isFlushed) {
transcript += "\n"
}
}
Create an instance of Cheetah
on the main thread:
const handle = await Cheetah.create(
${ACCESS_KEY},
transcriptCallback,
cheetahModel,
options
);
Or create an instance of Cheetah
in a worker thread:
const handle = await CheetahWorker.create(
${ACCESS_KEY},
transcriptCallback,
cheetahModel,
options
);
Process Audio Frames
The process
function will send the input frames to the engine.
The transcript is received from transcriptCallback
as mentioned above.
function getAudioData(): Int16Array {
...
return new Int16Array();
}
for (;;) {
handle.process(getAudioData());
}
handle.flush();
Clean Up
Clean up used resources by Cheetah
or CheetahWorker
:
await handle.release();
Terminate (Worker only)
Terminate CheetahWorker
instance:
await handle.terminate();
Demo
For example usage refer to our Web demo application.