Flutter Config toJson/fromJson (#1893)

flutter/sherpa_onnx/lib/src/vad.dart

@@ -14,11 +14,33 @@ class SileroVadModelConfig {
       this.windowSize = 512,
       this.maxSpeechDuration = 5.0});
 
+  factory SileroVadModelConfig.fromJson(Map<String, dynamic> json) {
+    return SileroVadModelConfig(
+      model: json['model'] as String? ?? '',
+      threshold: (json['threshold'] as num?)?.toDouble() ?? 0.5,
+      minSilenceDuration:
+          (json['minSilenceDuration'] as num?)?.toDouble() ?? 0.5,
+      minSpeechDuration:
+          (json['minSpeechDuration'] as num?)?.toDouble() ?? 0.25,
+      windowSize: json['windowSize'] as int? ?? 512,
+      maxSpeechDuration: (json['maxSpeechDuration'] as num?)?.toDouble() ?? 5.0,
+    );
+  }
+
   @override
   String toString() {
     return 'SileroVadModelConfig(model: $model, threshold: $threshold, minSilenceDuration: $minSilenceDuration, minSpeechDuration: $minSpeechDuration, windowSize: $windowSize, maxSpeechDuration: $maxSpeechDuration)';
   }
 
+  Map<String, dynamic> toJson() => {
+        'model': model,
+        'threshold': threshold,
+        'minSilenceDuration': minSilenceDuration,
+        'minSpeechDuration': minSpeechDuration,
+        'windowSize': windowSize,
+        'maxSpeechDuration': maxSpeechDuration,
+      };
+
   final String model;
   final double threshold;
   final double minSilenceDuration;
@@ -28,23 +50,43 @@ class SileroVadModelConfig {
 }
 
 class VadModelConfig {
-  VadModelConfig(
-      {this.sileroVad = const SileroVadModelConfig(),
-      this.sampleRate = 16000,
-      this.numThreads = 1,
-      this.provider = 'cpu',
-      this.debug = true});
-
-  @override
-  String toString() {
-    return 'VadModelConfig(sileroVad: $sileroVad, sampleRate: $sampleRate, numThreads: $numThreads, provider: $provider, debug: $debug)';
-  }
+  VadModelConfig({
+    this.sileroVad = const SileroVadModelConfig(),
+    this.sampleRate = 16000,
+    this.numThreads = 1,
+    this.provider = 'cpu',
+    this.debug = true,
+  });
 
   final SileroVadModelConfig sileroVad;
   final int sampleRate;
   final int numThreads;
   final String provider;
   final bool debug;
+
+  factory VadModelConfig.fromJson(Map<String, dynamic> json) {
+    return VadModelConfig(
+      sileroVad: SileroVadModelConfig.fromJson(
+          json['sileroVad'] as Map<String, dynamic>? ?? const {}),
+      sampleRate: json['sampleRate'] as int? ?? 16000,
+      numThreads: json['numThreads'] as int? ?? 1,
+      provider: json['provider'] as String? ?? 'cpu',
+      debug: json['debug'] as bool? ?? true,
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'sileroVad': sileroVad.toJson(),
+        'sampleRate': sampleRate,
+        'numThreads': numThreads,
+        'provider': provider,
+        'debug': debug,
+      };
+
+  @override
+  String toString() {
+    return 'VadModelConfig(sileroVad: $sileroVad, sampleRate: $sampleRate, numThreads: $numThreads, provider: $provider, debug: $debug)';
+  }
 }
 
 class SpeechSegment {