From 55c9dccdd3a9d04c71e8f2fc0ab25366aec3c09a Mon Sep 17 00:00:00 2001
From: Kristina <kristin.fefelova@gmail.com>
Date: Wed, 2 Apr 2025 15:14:54 +0400
Subject: [PATCH] Fix transcript score (#8434)

Signed-off-by: Kristina Fefelova <kristin.fefelova@gmail.com>
---
 services/ai-bot/love-agent/src/config.ts     |  8 ++++++-
 services/ai-bot/love-agent/src/openai/stt.ts | 25 +++++++++++++-------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/services/ai-bot/love-agent/src/config.ts b/services/ai-bot/love-agent/src/config.ts
index 3572e640c2..fec9e33149 100644
--- a/services/ai-bot/love-agent/src/config.ts
+++ b/services/ai-bot/love-agent/src/config.ts
@@ -26,6 +26,9 @@ interface Config {
   PlatformToken: string
   PlatformUrl: string
   SttProvider: SttProvider
+  VadSilenceDurationMs: number
+  VadPrefixPaddingMs: number
+  VadThreshold: number
 }
 
 const config: Config = (() => {
@@ -39,7 +42,10 @@ const config: Config = (() => {
     OpenaiProvideLanguage: (process.env.OPENAI_PROVIDE_LANGUAGE ?? 'true') === 'true',
     PlatformToken: process.env.PLATFORM_TOKEN,
     PlatformUrl: process.env.PLATFORM_URL,
-    SttProvider: (process.env.STT_PROVIDER as SttProvider) ?? 'deepgram'
+    SttProvider: (process.env.STT_PROVIDER as SttProvider) ?? 'deepgram',
+    VadSilenceDurationMs: parseInt(process.env.SILENCE_DURATION_MS ?? '1000'),
+    VadPrefixPaddingMs: parseInt(process.env.PREFIX_PADDING_MS ?? '1000'),
+    VadThreshold: parseFloat(process.env.VAD_THRESHOLD ?? '0.5')
   }
 
   const missingEnv = (Object.keys(params) as Array<keyof Config>).filter((key) => params[key] === undefined)
diff --git a/services/ai-bot/love-agent/src/openai/stt.ts b/services/ai-bot/love-agent/src/openai/stt.ts
index 297c6e031e..0f42588c93 100644
--- a/services/ai-bot/love-agent/src/openai/stt.ts
+++ b/services/ai-bot/love-agent/src/openai/stt.ts
@@ -156,9 +156,9 @@ export class STT implements Stt {
             },
             turn_detection: {
               type: 'server_vad',
-              threshold: 0.7,
-              prefix_padding_ms: 1000,
-              silence_duration_ms: 2000
+              threshold: config.VadThreshold,
+              prefix_padding_ms: config.VadPrefixPaddingMs,
+              silence_duration_ms: config.VadSilenceDurationMs
             },
             include: ['item.input_audio_transcription.logprobs']
           }
@@ -211,8 +211,12 @@ export class STT implements Stt {
 
   private onTranscriptCompleted (sid: string, data: any): void {
     if (data.transcript == null || data.transcript.trim() === '') return
-    const score = data.logprobs != null && Array.isArray(data.logprobs) ? getTranscriptProbability(data.logprobs.map((lp: any) => lp.logprob)) : undefined
-    const result = score !== undefined ? `${data.transcript} (${score.toFixed(2)})` : data.transcript
+    const logprobs: number[] =
+      data.logprobs != null && Array.isArray(data.logprobs) ? data.logprobs.map((lp: any) => lp.logprob) : []
+    const probability = getAvgProbability(logprobs)
+    const perplexity = getPerplexity(logprobs)
+
+    const result = probability !== undefined ? `${data.transcript} (${probability}, ${perplexity})` : data.transcript
 
     void this.sendToPlatform(result, sid)
   }
@@ -282,7 +286,12 @@ export class STT implements Stt {
   }
 }
 
-function getTranscriptProbability (logprobs: number[]): number {
-  const sum = logprobs.reduce((acc, lp) => acc + lp, 0)
-  return Math.exp(sum)
+function getAvgProbability (logprobs: number[]): string {
+  const avgLogProb = logprobs.reduce((acc, lp) => acc + lp, 0) / logprobs.length
+  return Math.exp(avgLogProb).toFixed(2)
+}
+
+function getPerplexity (logprobs: number[]): string {
+  const avgLogProb = logprobs.reduce((acc, lp) => acc + lp, 0) / logprobs.length
+  return Math.exp(-avgLogProb).toFixed(2)
 }