Receive speech-to-text for different languages
This example describes how to use the Symbl.ai Streaming API to receive a speech-to-text transcription of a conversation in many different languages. This example uses both the JavaScript SDK and native JavaScript.
Connect
When we're connected to the Web Socket, we can define which language we use in the configuration. Here we set the languageCode
key to Spanish (es-ES
). For the full list, see Supported languages.
Configuration Snippet
{
config: {
meetingTitle: 'My Test Meeting',
confidenceThreshold: 0.7,
timezoneOffset: 480, // Offset in minutes from UTC
languageCode: 'es-ES',
sampleRateHertz: 44100,
}
}
Node.js Code Snippet
const {sdk} = require('symbl-node');
const uuid = require('uuid').v4;
(async () => {
try {
// Initialize the SDK. You can find the appId and appSecret at https://platform.symbl.ai.
await sdk.init({
appId: appId,
appSecret: appSecret,
basePath: 'https://api.symbl.ai',
})
// Need unique Id
const id = uuid()
// Start Real-time Request (Uses Real-time WebSocket API behind the scenes)
const connection = await sdk.startRealtimeRequest({
id,
insightTypes: ['action_item', 'question'],
config: {
meetingTitle: 'My Test Meeting',
confidenceThreshold: 0.7,
timezoneOffset: 480, // Offset in minutes from UTC
languageCode: 'es-ES',
sampleRateHertz: 44100,
},
speaker: {
// Optional, if not specified, will simply not send an email in the end.
userId: 'emailAddress', // Update with valid email
name: 'My name'
},
handlers: {
/**
* This will return live speech-to-text transcription of the call.
*/
onSpeechDetected: (data) => {
console.log(JSON.stringify(data))
if (data) {
const {punctuated} = data
console.log('Live: ', punctuated && punctuated.transcript)
}
},
/**
* When processed messages are available, this callback will be called.
*/
onMessageResponse: (data) => {
console.log('onMessageResponse', JSON.stringify(data, null, 2))
},
}
});
} catch (e) {
console.error(e);
}
})();
Connect Mic
After you connect, you want to connect to your device's microphone. This code is inserted after the connection
and before the closing of the try...catch
const micInputStream = micInstance.getAudioStream()
/** Raw audio stream */
micInputStream.on('data', (data) => {
// Push audio from Microphone to websocket connection
connection.sendAudio(data)
})
micInputStream.on('error', function (err) {
console.log('Error in Input Stream: ' + err)
})
micInputStream.on('startComplete', function () {
console.log('Started listening to Microphone.')
})
micInputStream.on('silence', function () {
console.log('Got SIGNAL silence')
})
micInstance.start()
setTimeout(async () => {
// Stop listening to microphone
micInstance.stop()
console.log('Stopped listening to Microphone.')
try {
// Stop connection
await connection.stop()
console.log('Connection Stopped.')
} catch (e) {
console.error('Error while stopping the connection.', e)
}
}, 60 * 1000) // Stop connection after 1 minute i.e. 60 secs
Testing
Create a JavaScript file named app.js
and copy this code into the file. Fill in the placeholder values with the proper values. Use NPM to install the required libraries: npm install symbl-node uuid
.
In a terminal window, run:
$ node app.js
Check the console for a success message.
Native JavaScript Code Snippet
const accessToken = accessToken;
// Refer to the Authentication section for how to generate the accessToken: https://docs.symbl.ai/docs/authenticate
const uuid = require('uuid').v4;
const connectionId = uuid();
const symblEndpoint = `wss://api.symbl.ai/v1/streaming/${connectionId}?access_token=${accessToken}`;
const ws = new WebSocket(symblEndpoint);
ws.onmessage = (event) => {
// You can find the conversationId in event.message.data.conversationId;
const data = JSON.parse(event.data);
if (data.type === 'message' && data.message.hasOwnProperty('data')) {
console.log('conversationId', data.message.data.conversationId);
}
console.log('onmessage event', event);
};
// Fired when the WebSocket closes unexpectedly due to an error or lost connetion
ws.onerror = (err) => {
console.error(err);
};
// Fired when the WebSocket connection has been closed
ws.onclose = (event) => {
console.info('Connection to websocket closed');
};
// Fired when the connection succeeds.
ws.onopen = (event) => {
ws.send(JSON.stringify({
type: 'start_request',
meetingTitle: 'Websockets How-to', // Conversation name
insightTypes: ['question', 'action_item'], // Will enable insight generation
config: {
confidenceThreshold: 0.5,
languageCode: 'es-ES',
speechRecognition: {
encoding: 'LINEAR16',
sampleRateHertz: 44100,
}
},
speaker: {
userId: '[email protected]',
name: 'Example Sample',
}
}));
};
Backward Compatibility
The previous endpoint
wss://api.symbl.ai/v1/realtime/insights/
is now updated towss://api.symbl.ai/v1/streaming/
to standardize our API nomenclature. This change is backward compatible. However, we recommend you to use the new endpoint.
Connect Mic
After you connect, you want to connect to your device's microphone. This code is inserted after the ws.onopen
function:
const stream = await navigator.mediaDevices.getUserMedia({ audio: true, video: false });
/**
* The callback function which fires after a user gives the browser permission to use
* the computer's microphone. Starts a recording session which sends the audio stream to
* the WebSocket endpoint for processing.
*/
const handleSuccess = (stream) => {
const AudioContext = window.AudioContext;
const context = new AudioContext();
const source = context.createMediaStreamSource(stream);
const processor = context.createScriptProcessor(1024, 1, 1);
const gainNode = context.createGain();
source.connect(gainNode);
gainNode.connect(processor);
processor.connect(context.destination);
processor.onaudioprocess = (e) => {
// convert to 16-bit payload
const inputData = e.inputBuffer.getChannelData(0) || new Float32Array(this.bufferSize);
const targetBuffer = new Int16Array(inputData.length);
for (let index = inputData.length; index > 0; index--) {
targetBuffer[index] = 32767 * Math.min(1, inputData[index]);
}
// Send audio stream to websocket.
if (ws.readyState === WebSocket.OPEN) {
ws.send(targetBuffer.buffer);
}
};
};
handleSuccess(stream);
Testing
Open up your browser's development environment and copy this code into the console. Replace the placeholder values with the proper values.
If successful you should receive a response in the console.
Handlers Reference (Symbl SDK)
-
handlers
: This object has the callback functions for different eventsonSpeechDetected
: To retrieve the real-time transcription results as soon as they are detected. You can use this callback to render live transcription which is specific to the speaker of this audio stream.
onSpeechDetected JSON Response Example{ "type": "recognition_result", "isFinal": true, "payload": { "raw": { "alternatives": [{ "words": [{ "word": "Hello", "startTime": { "seconds": "3", "nanos": "800000000" }, "endTime": { "seconds": "4", "nanos": "200000000" } }, { "word": "world.", "startTime": { "seconds": "4", "nanos": "200000000" }, "endTime": { "seconds": "4", "nanos": "800000000" } }], "transcript": "Hello world.", "confidence": 0.9128385782241821 }] } }, "punctuated": { "transcript": "Hello world." }, "user": { "userId": "emailAddress", "name": "John Doe", "id": "23681108-355b-4fc3-9d94-ed47dd39fa56" } }
onMessageResponse
: This callback function contains the "finalized" transcription data for this speaker and if used with multiple streams with other speakers this callback would also provide their messages.
The "finalized" messages mean that the automatic speech recognition has finalized the state of this part of transcription and has declared it "final". Therefore, this transcription will be more accurate thanonSpeechDetected
.
onMessageResponse JSON Response Example[{ "from": { "id": "0a7a36b1-047d-4d8c-8958-910317ed9edc", "name": "John Doe", "userId": "emailAddress" }, "payload": { "content": "Hello world.", "contentType": "text/plain" }, "id": "59c224c2-54c5-4762-9582-961bf250b478", "channel": { "id": "realtime-api" }, "metadata": { "disablePunctuation": true, "timezoneOffset": 480, "originalContent": "Hello world.", "words": "[{\"word\":\"Hello\",\"startTime\":\"2021-02-04T20:34:59.029Z\",\"endTime\":\"2021-02-04T20:34:59.429Z\"},{\"word\":\"world.\",\"startTime\":\"2021-02-04T20:34:59.429Z\",\"endTime\":\"2021-02-04T20:35:00.029Z\"}]", "originalMessageId": "59c224c2-54c5-4762-9582-961bf250b478" }, "dismissed": false, "duration": { "startTime": "2021-02-04T20:34:59.029Z", "endTime": "2021-02-04T20:35:00.029Z" } }]
Updated over 1 year ago