Add Dart API for speech enhancement GTCRN models (#1993)

flutter/sherpa_onnx/lib/src/offline_speech_denoiser.dart

@@ -0,0 +1,169 @@
+// Copyright (c)  2025  Xiaomi Corporation
+import 'dart:ffi';
+import 'dart:typed_data';
+
+import 'package:ffi/ffi.dart';
+import './sherpa_onnx_bindings.dart';
+
+class OfflineSpeechDenoiserGtcrnModelConfig {
+  const OfflineSpeechDenoiserGtcrnModelConfig({
+    this.model = '',
+  });
+
+  factory OfflineSpeechDenoiserGtcrnModelConfig.fromJson(
+      Map<String, dynamic> json) {
+    return OfflineSpeechDenoiserGtcrnModelConfig(
+      model: json['model'] as String? ?? '',
+    );
+  }
+
+  @override
+  String toString() {
+    return 'OfflineSpeechDenoiserGtcrnModelConfig(model: $model)';
+  }
+
+  Map<String, dynamic> toJson() => {
+        'model': model,
+      };
+
+  final String model;
+}
+
+class OfflineSpeechDenoiserModelConfig {
+  const OfflineSpeechDenoiserModelConfig({
+    this.gtcrn = const OfflineSpeechDenoiserGtcrnModelConfig(),
+    this.numThreads = 1,
+    this.debug = true,
+    this.provider = 'cpu',
+  });
+
+  factory OfflineSpeechDenoiserModelConfig.fromJson(Map<String, dynamic> json) {
+    return OfflineSpeechDenoiserModelConfig(
+      gtcrn: json['gtcrn'] != null
+          ? OfflineSpeechDenoiserGtcrnModelConfig.fromJson(
+              json['gtcrn'] as Map<String, dynamic>)
+          : const OfflineSpeechDenoiserGtcrnModelConfig(),
+      numThreads: json['numThreads'] as int? ?? 1,
+      debug: json['debug'] as bool? ?? true,
+      provider: json['provider'] as String? ?? 'cpu',
+    );
+  }
+
+  @override
+  String toString() {
+    return 'OfflineSpeechDenoiserModelConfig(gtcrn: $gtcrn, numThreads: $numThreads, debug: $debug, provider: $provider)';
+  }
+
+  Map<String, dynamic> toJson() => {
+        'gtcrn': gtcrn.toJson(),
+        'numThreads': numThreads,
+        'debug': debug,
+        'provider': provider,
+      };
+
+  final OfflineSpeechDenoiserGtcrnModelConfig gtcrn;
+  final int numThreads;
+  final bool debug;
+  final String provider;
+}
+
+class OfflineSpeechDenoiserConfig {
+  const OfflineSpeechDenoiserConfig({
+    this.model = const OfflineSpeechDenoiserModelConfig(),
+  });
+
+  factory OfflineSpeechDenoiserConfig.fromJson(Map<String, dynamic> json) {
+    return OfflineSpeechDenoiserConfig(
+      model: json['model'] != null
+          ? OfflineSpeechDenoiserModelConfig.fromJson(
+              json['model'] as Map<String, dynamic>)
+          : const OfflineSpeechDenoiserModelConfig(),
+    );
+  }
+
+  @override
+  String toString() {
+    return 'OfflineSpeechDenoiserConfig(model: $model)';
+  }
+
+  Map<String, dynamic> toJson() => {
+        'model': model.toJson(),
+      };
+
+  final OfflineSpeechDenoiserModelConfig model;
+}
+
+class DenoisedAudio {
+  DenoisedAudio({
+    required this.samples,
+    required this.sampleRate,
+  });
+
+  final Float32List samples;
+  final int sampleRate;
+}
+
+class OfflineSpeechDenoiser {
+  OfflineSpeechDenoiser.fromPtr({required this.ptr, required this.config});
+
+  OfflineSpeechDenoiser._({required this.ptr, required this.config});
+
+  /// The user is responsible to call the OfflineSpeechDenoiser.free()
+  /// method of the returned instance to avoid memory leak.
+  factory OfflineSpeechDenoiser(OfflineSpeechDenoiserConfig config) {
+    final c = calloc<SherpaOnnxOfflineSpeechDenoiserConfig>();
+    c.ref.model.gtcrn.model = config.model.gtcrn.model.toNativeUtf8();
+
+    c.ref.model.numThreads = config.model.numThreads;
+    c.ref.model.debug = config.model.debug ? 1 : 0;
+    c.ref.model.provider = config.model.provider.toNativeUtf8();
+
+    final ptr =
+        SherpaOnnxBindings.sherpaOnnxCreateOfflineSpeechDenoiser?.call(c) ??
+            nullptr;
+
+    calloc.free(c.ref.model.provider);
+    calloc.free(c.ref.model.gtcrn.model);
+
+    return OfflineSpeechDenoiser._(ptr: ptr, config: config);
+  }
+
+  void free() {
+    SherpaOnnxBindings.sherpaOnnxDestroyOfflineSpeechDenoiser?.call(ptr);
+    ptr = nullptr;
+  }
+
+  DenoisedAudio run({required Float32List samples, required int sampleRate}) {
+    final n = samples.length;
+    final Pointer<Float> psamples = calloc<Float>(n);
+
+    final pList = psamples.asTypedList(n);
+    pList.setAll(0, samples);
+
+    final p = SherpaOnnxBindings.sherpaOnnxOfflineSpeechDenoiserRun
+            ?.call(ptr, psamples, n, sampleRate) ??
+        nullptr;
+
+    calloc.free(psamples);
+
+    if (p == nullptr) {
+      return DenoisedAudio(samples: Float32List(0), sampleRate: 0);
+    }
+
+    final denoisedSamples = p.ref.samples.asTypedList(p.ref.n);
+    final denoisedSampleRate = p.ref.sampleRate;
+    final newSamples = Float32List.fromList(denoisedSamples);
+
+    SherpaOnnxBindings.sherpaOnnxDestroyDenoisedAudio?.call(p);
+
+    return DenoisedAudio(samples: newSamples, sampleRate: denoisedSampleRate);
+  }
+
+  int get sampleRate =>
+      SherpaOnnxBindings.sherpaOnnxOfflineSpeechDenoiserGetSampleRate
+          ?.call(ptr) ??
+      0;
+
+  Pointer<SherpaOnnxOfflineSpeechDenoiser> ptr;
+  OfflineSpeechDenoiserConfig config;
+}