Developers

1// Buffer to hold incoming audio chunks before the upstream session is ready
2const audioBuffer: Buffer[] = [];
3let sessionReady = false;
4
5// Open a streaming ASR session with the UltraSafe API
6const session = usf.audio.stream.connect({
7  model: 'usf-mini-asr',
8  sampleRate: 16000,
9  audioFormat: 'pcm_s16le',
10  enableVad: false,
11  partialResults: true,
12  interimMinDurationMs: 500,
13  fullContextRetranscription: true,
14});
15
16// Once the upstream session is open, flush any buffered audio
17session.onopen = () => {
18  sessionReady = true;
19  for (const chunk of audioBuffer) session.sendAudio(chunk);
20  audioBuffer.length = 0;
21};
22
23// Forward transcript events to the client WebSocket
24session.ontranscript = (event) => {
25  if (socket.readyState === 1) socket.send(JSON.stringify(event));
26};
27
28// Propagate upstream session close to the client
29session.onclose = (code, reason) => {
30  if (socket.readyState === 1) socket.close(code, reason);
31};
32
33// On upstream error, notify the client and close
34session.onerror = (err) => {
35  if (socket.readyState === 1) {
36    socket.send(JSON.stringify({ error: err.message }));
37    socket.close();
38  }
39};
40
41// Relay incoming audio from the client to the upstream ASR session
42socket.on('message', (data: Buffer) => {
43  if (sessionReady) {
44    session.sendAudio(data);
45  } else {
46    audioBuffer.push(data);
47  }
48});
49
50// When the client disconnects, close the upstream ASR session
51socket.on('close', () => {
52  if (session.readyState === 1) session.close();
53});