const DEFAULT_SPEECH_RMS_THRESHOLD = 0.02;

const DEFAULT_REQUIRED_LOUD_CHUNKS = 2;

const DEFAULT_REQUIRED_QUIET_CHUNKS = 10;

const DEFAULT_MAX_QUEUED_AUDIO_BYTES = TELEPHONY_SAMPLE_RATE * 120;

const PCM16_MAX_AMPLITUDE = 32768;

const MULAW_LINEAR_SAMPLES = new Int16Array(256);

export class RealtimeTwilioAudioPacer {

private queue: RealtimeTwilioAudioQueueItem[] = [];

private timer: ReturnType<typeof setTimeout> | null = null;

private queuedAudioBytes = 0;

private closed = false;

constructor(

private readonly params: {

maxQueuedAudioBytes?: number;

onBackpressure?: () => void;

sendJson: RealtimeTwilioAudioPacerSendJson;

streamSid: string;

},

if (this.closed || muLaw.length === 0) {

return;

}

const maxQueuedAudioBytes = this.params.maxQueuedAudioBytes ?? DEFAULT_MAX_QUEUED_AUDIO_BYTES;

for (let offset = 0; offset < muLaw.length; offset += TELEPHONY_CHUNK_BYTES) {

const chunk = Buffer.from(muLaw.subarray(offset, offset + TELEPHONY_CHUNK_BYTES));

if (this.queuedAudioBytes + chunk.length > maxQueuedAudioBytes) {

this.failBackpressure();

return;

}

this.queue.push({

type: "audio",

chunk,

durationMs: Math.max(1, Math.round((chunk.length / TELEPHONY_SAMPLE_RATE) * 1000)),

});

this.queuedAudioBytes += chunk.length;

}

this.ensurePump();

}

}

this.clearTimer();

this.queue = [];

this.queuedAudioBytes = 0;

this.params.sendJson({ event: "clear", streamSid: this.params.streamSid });

}

close(): void {

this.closed = true;

this.clearTimer();

this.queue = [];

this.queuedAudioBytes = 0;

}

private clearTimer(): void {

}

}

private failBackpressure(): void {

this.close();

this.params.onBackpressure?.();

}

private pump(): void {

this.timer = null;

if (this.closed) {

let delayMs = 0;

let sent = true;

if (item.type === "audio") {

this.queuedAudioBytes = Math.max(0, this.queuedAudioBytes - item.chunk.length);

sent = this.params.sendJson({

event: "media",

streamSid: this.params.streamSid,

if (!sent) {

this.queue = [];

this.queuedAudioBytes = 0;

return;

}

if (this.queue.length > 0) {