ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

chapter6/live-audio/backend/utils/speechToText.js

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+const fs = require('fs');
+const path = require('path');
+const config = require('../config');
+const { ASRProviderFactory } = require('./providers/asrProviders');
+
+class SpeechToTextService {
+  constructor() {
+    this.tempDir = path.join(__dirname, '../temp');
+    this.ensureTempDirectory();
+    
+    // Initialize ASR provider based on configuration
+    this.initializeProvider();
+  }
+
+  /**
+   * Initialize ASR provider based on configuration
+   */
+  initializeProvider() {
+    try {
+      const providerName = config.ASR_PROVIDER || 'openai';
+      this.asrProvider = ASRProviderFactory.createProvider(providerName, config, config);
+      console.log(`ASR Provider initialized: ${providerName}`);
+    } catch (error) {
+      console.error('Failed to initialize ASR provider:', error);
+      throw error;
+    }
+  }
+
+  /**
+   * Switch ASR provider dynamically
+   * @param {string} providerName - Provider name to switch to
+   */
+  switchProvider(providerName) {
+    try {
+      this.asrProvider = ASRProviderFactory.createProvider(providerName, config, config);
+      console.log(`ASR Provider switched to: ${providerName}`);
+    } catch (error) {
+      console.error('Failed to switch ASR provider:', error);
+      throw error;
+    }
+  }
+
+  /**
+   * Ensure temp directory exists
+   */
+  ensureTempDirectory() {
+    if (!fs.existsSync(this.tempDir)) {
+      fs.mkdirSync(this.tempDir, { recursive: true });
+    }
+  }
+
+  /**
+   * Transcribe audio using the configured ASR provider
+   * @param {Buffer} audioBuffer - Raw audio data
+   * @param {Object} options - Transcription options
+   * @returns {Promise<Object>} Transcription result
+   */
+  async transcribeAudio(audioBuffer, options = {}) {
+    if (!this.asrProvider) {
+      throw new Error('ASR provider not initialized');
+    }
+
+    try {
+      const result = await this.asrProvider.transcribe(audioBuffer, this.tempDir, options);
+      return result;
+    } catch (error) {
+      console.error('Transcription error:', error);
+      return {
+        success: false,
+        text: '',
+        error: error.message,
+        timestamp: Date.now(),
+        provider: this.asrProvider.config ? 'unknown' : 'uninitialized'
+      };
+    }
+  }
+
+  /**
+   * Clean up old temporary files
+   */
+  cleanupTempFiles() {
+    try {
+      const files = fs.readdirSync(this.tempDir);
+      const now = Date.now();
+      const maxAge = 10 * 60 * 1000; // 10 minutes
+      
+      files.forEach(file => {
+        const filePath = path.join(this.tempDir, file);
+        const stats = fs.statSync(filePath);
+        
+        if (now - stats.mtime.getTime() > maxAge) {
+          try {
+            fs.unlinkSync(filePath);
+            console.log('Cleaned up old temp file:', file);
+          } catch (error) {
+            console.warn('Failed to cleanup old temp file:', file, error.message);
+          }
+        }
+      });
+    } catch (error) {
+      console.warn('Failed to cleanup temp directory:', error.message);
+    }
+  }
+
+  /**
+   * Check if audio buffer has sufficient content for transcription
+   * @param {Buffer} audioBuffer - Audio buffer to check
+   * @returns {boolean} True if buffer has sufficient content
+   */
+  hasSufficientAudio(audioBuffer) {
+    if (!audioBuffer || audioBuffer.length === 0) {
+      return false;
+    }
+
+    // Check minimum duration (at least 0.1 seconds of audio)
+    const minSamples = config.AUDIO_SAMPLE_RATE * 0.1; // 0.1 seconds
+    const minBytes = minSamples * 2; // 16-bit = 2 bytes per sample
+    
+    if (audioBuffer.length < minBytes) {
+      return false;
+    }
+
+    // Since we're using Silero VAD for speech detection, we trust its decision
+    // and only check for minimum duration. The energy check is redundant and
+    // can reject valid speech that Silero VAD correctly identified.
+    return true;
+  }
+
+  /**
+   * Get current provider information
+   * @returns {Object} Current provider information
+   */
+  getProviderInfo() {
+    if (!this.asrProvider) {
+      return { provider: 'none', status: 'not initialized' };
+    }
+
+    return {
+      provider: this.asrProvider.constructor.name,
+      model: this.asrProvider.config.model,
+      apiUrl: this.asrProvider.config.apiUrl,
+      status: 'ready'
+    };
+  }
+}
+
+module.exports = SpeechToTextService;