Wrap offline ASR APIs to dart (#961)

+// Copyright (c)  2024  Xiaomi Corporation
+import 'package:path/path.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:flutter/services.dart' show rootBundle;
+import 'dart:typed_data';
+import "dart:io";
+
+import 'package:sherpa_onnx/sherpa_onnx.dart' as sherpa_onnx;
+import './utils.dart';
+
+Future<void> testNonStreamingParaformerAsr() async {
+  var model = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/model.int8.onnx';
+  var tokens = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/tokens.txt';
+  var testWave = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/test_wavs/0.wav';
+
+  model = await copyAssetFile(src: model, dst: 'model.int8.onnx');
+  tokens = await copyAssetFile(src: tokens, dst: 'tokens.txt');
+  testWave = await copyAssetFile(src: testWave, dst: '0.wav');
+
+  final paraformer = sherpa_onnx.OfflineParaformerModelConfig(
+    model: model,
+  );
+
+  final modelConfig = sherpa_onnx.OfflineModelConfig(
+    paraformer: paraformer,
+    tokens: tokens,
+    modelType: 'paraformer',
+  );
+
+  final config = sherpa_onnx.OfflineRecognizerConfig(model: modelConfig);
+  print(config);
+  final recognizer = sherpa_onnx.OfflineRecognizer(config);
+
+  final waveData = sherpa_onnx.readWave(testWave);
+  final stream = recognizer.createStream();
+
+  stream.acceptWaveform(
+      samples: waveData.samples, sampleRate: waveData.sampleRate);
+  recognizer.decode(stream);
+
+  final result = recognizer.getResult(stream);
+  print('result is: ${result}');
+
+  print('recognizer: ${recognizer.ptr}');
+  stream.free();
+  recognizer.free();
+}

@@ -74,6 +74,8 @@ flutter:
   assets:
     - assets/
     - assets/sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/
+    # - assets/sherpa-onnx-paraformer-zh-2023-03-28/
+    # - assets/sherpa-onnx-paraformer-zh-2023-03-28/test_wavs/
   #   - assets/sr-data/enroll/
   #   - assets/sr-data/test/
   #   - images/a_dot_ham.jpeg

@@ -2,12 +2,16 @@
 import 'dart:io';
 import 'dart:ffi';
 
+export 'src/feature_config.dart';
+export 'src/offline_recognizer.dart';
+export 'src/offline_stream.dart';
 export 'src/online_recognizer.dart';
 export 'src/online_stream.dart';
 export 'src/speaker_identification.dart';
 export 'src/vad.dart';
 export 'src/wave_reader.dart';
 export 'src/wave_writer.dart';
+
 import 'src/sherpa_onnx_bindings.dart';
 
 final DynamicLibrary _dylib = () {

+// Copyright (c)  2024  Xiaomi Corporation
+
+class FeatureConfig {
+  const FeatureConfig({this.sampleRate = 16000, this.featureDim = 80});
+
+  @override
+  String toString() {
+    return 'FeatureConfig(sampleRate: $sampleRate, featureDim: $featureDim)';
+  }
+
+  final int sampleRate;
+  final int featureDim;
+}

+// Copyright (c)  2024  Xiaomi Corporation
+import 'dart:convert';
+import 'dart:ffi';
+import 'dart:typed_data';
+
+import 'package:ffi/ffi.dart';
+
+import './feature_config.dart';
+import './offline_stream.dart';
+import './sherpa_onnx_bindings.dart';
+
+class OfflineTransducerModelConfig {
+  const OfflineTransducerModelConfig({
+    this.encoder = '',
+    this.decoder = '',
+    this.joiner = '',
+  });
+
+  @override
+  String toString() {
+    return 'OfflineTransducerModelConfig(encoder: $encoder, decoder: $decoder, joiner: $joiner)';
+  }
+
+  final String encoder;
+  final String decoder;
+  final String joiner;
+}
+
+class OfflineParaformerModelConfig {
+  const OfflineParaformerModelConfig({this.model = ''});
+
+  @override
+  String toString() {
+    return 'OfflineParaformerModelConfig(model: $model)';
+  }
+
+  final String model;
+}
+
+class OfflineNemoEncDecCtcModelConfig {
+  const OfflineNemoEncDecCtcModelConfig({this.model = ''});
+
+  @override
+  String toString() {
+    return 'OfflineNemoEncDecCtcModelConfig(model: $model)';
+  }
+
+  final String model;
+}
+
+class OfflineWhisperModelConfig {
+  const OfflineWhisperModelConfig(
+      {this.encoder = '',
+      this.decoder = '',
+      this.language = '',
+      this.task = '',
+      this.tailPaddings = -1});
+
+  @override
+  String toString() {
+    return 'OfflineWhisperModelConfig(encoder: $encoder, decoder: $decoder, language: $language, task: $task, tailPaddings: $tailPaddings)';
+  }
+
+  final String encoder;
+  final String decoder;
+  final String language;
+  final String task;
+  final int tailPaddings;
+}
+
+class OfflineTdnnModelConfig {
+  const OfflineTdnnModelConfig({this.model = ''});
+
+  @override
+  String toString() {
+    return 'OfflineTdnnModelConfig(model: $model)';
+  }
+
+  final String model;
+}
+
+class OfflineLMConfig {
+  const OfflineLMConfig({this.model = '', this.scale = 1.0});
+
+  @override
+  String toString() {
+    return 'OfflineLMConfig(model: $model, scale: $scale)';
+  }
+
+  final String model;
+  final double scale;
+}
+
+class OfflineModelConfig {
+  const OfflineModelConfig({
+    this.transducer = const OfflineTransducerModelConfig(),
+    this.paraformer = const OfflineParaformerModelConfig(),
+    this.nemoCtc = const OfflineNemoEncDecCtcModelConfig(),
+    this.whisper = const OfflineWhisperModelConfig(),
+    this.tdnn = const OfflineTdnnModelConfig(),
+    required this.tokens,
+    this.numThreads = 1,
+    this.debug = true,
+    this.provider = 'cpu',
+    this.modelType = '',
+  });
+
+  @override
+  String toString() {
+    return 'OfflineModelConfig(transducer: $transducer, paraformer: $paraformer, nemoCtc: $nemoCtc, whisper: $whisper, tdnn: $tdnn, tokens: $tokens, numThreads: $numThreads, debug: $debug, provider: $provider, modelType: $modelType)';
+  }
+
+  final OfflineTransducerModelConfig transducer;
+  final OfflineParaformerModelConfig paraformer;
+  final OfflineNemoEncDecCtcModelConfig nemoCtc;
+  final OfflineWhisperModelConfig whisper;
+  final OfflineTdnnModelConfig tdnn;
+
+  final String tokens;
+  final int numThreads;
+  final bool debug;
+  final String provider;
+  final String modelType;
+}
+
+class OfflineRecognizerConfig {
+  const OfflineRecognizerConfig({
+    this.feat = const FeatureConfig(),
+    required this.model,
+    this.lm = const OfflineLMConfig(),
+    this.decodingMethod = 'greedy_search',
+    this.maxActivePaths = 4,
+    this.hotwordsFile = '',
+    this.hotwordsScore = 1.5,
+  });
+
+  @override
+  String toString() {
+    return 'OfflineRecognizerConfig(feat: $feat, model: $model, lm: $lm, decodingMethod: $decodingMethod, maxActivePaths: $maxActivePaths, hotwordsFile: $hotwordsFile, hotwordsScore: $hotwordsScore)';
+  }
+
+  final FeatureConfig feat;
+  final OfflineModelConfig model;
+  final OfflineLMConfig lm;
+  final String decodingMethod;
+
+  final int maxActivePaths;
+
+  final String hotwordsFile;
+
+  final double hotwordsScore;
+}
+
+class OfflineRecognizerResult {
+  OfflineRecognizerResult(
+      {required this.text, required this.tokens, required this.timestamps});
+
+  @override
+  String toString() {
+    return 'OfflineRecognizerResult(text: $text, tokens: $tokens, timestamps: $timestamps)';
+  }
+
+  final String text;
+  final List<String> tokens;
+  final List<double> timestamps;
+}
+
+class OfflineRecognizer {
+  OfflineRecognizer._({required this.ptr, required this.config});
+
+  void free() {
+    SherpaOnnxBindings.destroyOfflineRecognizer?.call(ptr);
+    ptr = nullptr;
+  }
+
+  /// The user is responsible to call the OfflineRecognizer.free()
+  /// method of the returned instance to avoid memory leak.
+  factory OfflineRecognizer(OfflineRecognizerConfig config) {
+    final c = calloc<SherpaOnnxOfflineRecognizerConfig>();
+
+    c.ref.feat.sampleRate = config.feat.sampleRate;
+    c.ref.feat.featureDim = config.feat.featureDim;
+
+    // transducer
+    c.ref.model.transducer.encoder =
+        config.model.transducer.encoder.toNativeUtf8();
+    c.ref.model.transducer.decoder =
+        config.model.transducer.decoder.toNativeUtf8();
+    c.ref.model.transducer.joiner =
+        config.model.transducer.joiner.toNativeUtf8();
+
+    // paraformer
+    c.ref.model.paraformer.model = config.model.paraformer.model.toNativeUtf8();
+
+    // nemoCtc
+    c.ref.model.nemoCtc.model = config.model.nemoCtc.model.toNativeUtf8();
+
+    // whisper
+    c.ref.model.whisper.encoder = config.model.whisper.encoder.toNativeUtf8();
+
+    c.ref.model.whisper.decoder = config.model.whisper.decoder.toNativeUtf8();
+
+    c.ref.model.whisper.language = config.model.whisper.language.toNativeUtf8();
+
+    c.ref.model.whisper.task = config.model.whisper.task.toNativeUtf8();
+
+    c.ref.model.whisper.tailPaddings = config.model.whisper.tailPaddings;
+
+    c.ref.model.tdnn.model = config.model.tdnn.model.toNativeUtf8();
+
+    c.ref.model.tokens = config.model.tokens.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();
+    c.ref.model.modelType = config.model.modelType.toNativeUtf8();
+
+    c.ref.lm.model = config.lm.model.toNativeUtf8();
+    c.ref.lm.scale = config.lm.scale;
+
+    c.ref.decodingMethod = config.decodingMethod.toNativeUtf8();
+    c.ref.maxActivePaths = config.maxActivePaths;
+
+    c.ref.hotwordsFile = config.hotwordsFile.toNativeUtf8();
+    c.ref.hotwordsScore = config.hotwordsScore;
+
+    final ptr = SherpaOnnxBindings.createOfflineRecognizer?.call(c) ?? nullptr;
+
+    calloc.free(c.ref.hotwordsFile);
+    calloc.free(c.ref.decodingMethod);
+    calloc.free(c.ref.lm.model);
+    calloc.free(c.ref.model.modelType);
+    calloc.free(c.ref.model.provider);
+    calloc.free(c.ref.model.tokens);
+    calloc.free(c.ref.model.tdnn.model);
+    calloc.free(c.ref.model.whisper.task);
+    calloc.free(c.ref.model.whisper.language);
+    calloc.free(c.ref.model.whisper.decoder);
+    calloc.free(c.ref.model.whisper.encoder);
+    calloc.free(c.ref.model.nemoCtc.model);
+    calloc.free(c.ref.model.paraformer.model);
+    calloc.free(c.ref.model.transducer.encoder);
+    calloc.free(c.ref.model.transducer.decoder);
+    calloc.free(c.ref.model.transducer.joiner);
+    calloc.free(c);
+
+    return OfflineRecognizer._(ptr: ptr, config: config);
+  }
+
+  /// The user has to invoke stream.free() on the returned instance
+  /// to avoid memory leak
+  OfflineStream createStream() {
+    final p = SherpaOnnxBindings.createOfflineStream?.call(ptr) ?? nullptr;
+    return OfflineStream(ptr: p);
+  }
+
+  void decode(OfflineStream stream) {
+    SherpaOnnxBindings.decodeOfflineStream?.call(ptr, stream.ptr);
+  }
+
+  OfflineRecognizerResult getResult(OfflineStream stream) {
+    final json =
+        SherpaOnnxBindings.getOfflineStreamResultAsJson?.call(stream.ptr) ??
+            nullptr;
+    if (json == null) {
+      return OfflineRecognizerResult(text: '', tokens: [], timestamps: []);
+    }
+
+    final parsedJson = jsonDecode(json.toDartString());
+
+    SherpaOnnxBindings.destroyOfflineStreamResultJson?.call(json);
+
+    return OfflineRecognizerResult(
+        text: parsedJson['text'],
+        tokens: List<String>.from(parsedJson['tokens']),
+        timestamps: List<double>.from(parsedJson['timestamps']));
+  }
+
+  Pointer<SherpaOnnxOfflineRecognizer> ptr;
+  OfflineRecognizerConfig config;
+}

+// Copyright (c)  2024  Xiaomi Corporation
+import 'dart:ffi';
+import 'dart:typed_data';
+import 'package:ffi/ffi.dart';
+
+import './sherpa_onnx_bindings.dart';
+
+class OfflineStream {
+  /// The user has to call OfflineStream.free() to avoid memory leak.
+  OfflineStream({required this.ptr});
+
+  void free() {
+    SherpaOnnxBindings.destroyOfflineStream?.call(ptr);
+    ptr = nullptr;
+  }
+
+  /// If you have List<double> data, then you can use
+  /// Float32List.fromList(data) to convert data to Float32List
+  ///
+  /// See
+  ///  https://api.flutter.dev/flutter/dart-core/List-class.html
+  /// and
+  ///  https://api.flutter.dev/flutter/dart-typed_data/Float32List-class.html
+  void acceptWaveform({required Float32List samples, required int sampleRate}) {
+    final n = samples.length;
+    final Pointer<Float> p = calloc<Float>(n);
+
+    final pList = p.asTypedList(n);
+    pList.setAll(0, samples);
+
+    SherpaOnnxBindings.acceptWaveformOffline?.call(this.ptr, sampleRate, p, n);
+
+    calloc.free(p);
+  }
+
+  Pointer<SherpaOnnxOfflineStream> ptr;
+}

@@ -5,21 +5,10 @@ import 'dart:typed_data';
 
 import 'package:ffi/ffi.dart';
 
+import './feature_config.dart';
 import './online_stream.dart';
 import './sherpa_onnx_bindings.dart';
 
-class FeatureConfig {
-  const FeatureConfig({this.sampleRate = 16000, this.featureDim = 80});
-
-  @override
-  String toString() {
-    return 'FeatureConfig(sampleRate: $sampleRate, featureDim: $featureDim)';
-  }
-
-  final int sampleRate;
-  final int featureDim;
-}
-
 class OnlineTransducerModelConfig {
   const OnlineTransducerModelConfig({
     this.encoder = '',

@@ -10,6 +10,76 @@ final class SherpaOnnxFeatureConfig extends Struct {
   external int featureDim;
 }
 
+final class SherpaOnnxOfflineTransducerModelConfig extends Struct {
+  external Pointer<Utf8> encoder;
+  external Pointer<Utf8> decoder;
+  external Pointer<Utf8> joiner;
+}
+
+final class SherpaOnnxOfflineParaformerModelConfig extends Struct {
+  external Pointer<Utf8> model;
+}
+
+final class SherpaOnnxOfflineNemoEncDecCtcModelConfig extends Struct {
+  external Pointer<Utf8> model;
+}
+
+final class SherpaOnnxOfflineWhisperModelConfig extends Struct {
+  external Pointer<Utf8> encoder;
+  external Pointer<Utf8> decoder;
+  external Pointer<Utf8> language;
+  external Pointer<Utf8> task;
+
+  @Int32()
+  external int tailPaddings;
+}
+
+final class SherpaOnnxOfflineTdnnModelConfig extends Struct {
+  external Pointer<Utf8> model;
+}
+
+final class SherpaOnnxOfflineLMConfig extends Struct {
+  external Pointer<Utf8> model;
+
+  @Float()
+  external double scale;
+}
+
+final class SherpaOnnxOfflineModelConfig extends Struct {
+  external SherpaOnnxOfflineTransducerModelConfig transducer;
+  external SherpaOnnxOfflineParaformerModelConfig paraformer;
+  external SherpaOnnxOfflineNemoEncDecCtcModelConfig nemoCtc;
+  external SherpaOnnxOfflineWhisperModelConfig whisper;
+  external SherpaOnnxOfflineTdnnModelConfig tdnn;
+
+  external Pointer<Utf8> tokens;
+
+  @Int32()
+  external int numThreads;
+
+  @Int32()
+  external int debug;
+
+  external Pointer<Utf8> provider;
+
+  external Pointer<Utf8> modelType;
+}
+
+final class SherpaOnnxOfflineRecognizerConfig extends Struct {
+  external SherpaOnnxFeatureConfig feat;
+  external SherpaOnnxOfflineModelConfig model;
+  external SherpaOnnxOfflineLMConfig lm;
+  external Pointer<Utf8> decodingMethod;
+
+  @Int32()
+  external int maxActivePaths;
+
+  external Pointer<Utf8> hotwordsFile;
+
+  @Float()
+  external double hotwordsScore;
+}
+
 final class SherpaOnnxOnlineTransducerModelConfig extends Struct {
   external Pointer<Utf8> encoder;
   external Pointer<Utf8> decoder;
@@ -149,10 +219,56 @@ final class SherpaOnnxOnlineStream extends Opaque {}
 
 final class SherpaOnnxOnlineRecognizer extends Opaque {}
 
+final class SherpaOnnxOfflineRecognizer extends Opaque {}
+
+final class SherpaOnnxOfflineStream extends Opaque {}
+
 final class SherpaOnnxSpeakerEmbeddingExtractor extends Opaque {}
 
 final class SherpaOnnxSpeakerEmbeddingManager extends Opaque {}
 
+typedef CreateOfflineRecognizerNative = Pointer<SherpaOnnxOfflineRecognizer>
+    Function(Pointer<SherpaOnnxOfflineRecognizerConfig>);
+
+typedef CreateOfflineRecognizer = CreateOfflineRecognizerNative;
+
+typedef DestroyOfflineRecognizerNative = Void Function(
+    Pointer<SherpaOnnxOfflineRecognizer>);
+
+typedef DestroyOfflineRecognizer = void Function(
+    Pointer<SherpaOnnxOfflineRecognizer>);
+
+typedef CreateOfflineStreamNative = Pointer<SherpaOnnxOfflineStream> Function(
+    Pointer<SherpaOnnxOfflineRecognizer>);
+
+typedef CreateOfflineStream = CreateOfflineStreamNative;
+
+typedef DestroyOfflineStreamNative = Void Function(
+    Pointer<SherpaOnnxOfflineStream>);
+
+typedef DestroyOfflineStream = void Function(Pointer<SherpaOnnxOfflineStream>);
+
+typedef AcceptWaveformOfflineNative = Void Function(
+    Pointer<SherpaOnnxOfflineStream>, Int32, Pointer<Float>, Int32);
+
+typedef AcceptWaveformOffline = void Function(
+    Pointer<SherpaOnnxOfflineStream>, int, Pointer<Float>, int);
+
+typedef DecodeOfflineStreamNative = Void Function(
+    Pointer<SherpaOnnxOfflineRecognizer>, Pointer<SherpaOnnxOfflineStream>);
+
+typedef DecodeOfflineStream = void Function(
+    Pointer<SherpaOnnxOfflineRecognizer>, Pointer<SherpaOnnxOfflineStream>);
+
+typedef GetOfflineStreamResultAsJsonNative = Pointer<Utf8> Function(
+    Pointer<SherpaOnnxOfflineStream>);
+
+typedef GetOfflineStreamResultAsJson = GetOfflineStreamResultAsJsonNative;
+
+typedef DestroyOfflineStreamResultJsonNative = Void Function(Pointer<Utf8>);
+
+typedef DestroyOfflineStreamResultJson = void Function(Pointer<Utf8>);
+
 typedef CreateOnlineRecognizerNative = Pointer<SherpaOnnxOnlineRecognizer>
     Function(Pointer<SherpaOnnxOnlineRecognizerConfig>);
 
@@ -488,6 +604,15 @@ typedef SherpaOnnxFreeWaveNative = Void Function(Pointer<SherpaOnnxWave>);
 typedef SherpaOnnxFreeWave = void Function(Pointer<SherpaOnnxWave>);
 
 class SherpaOnnxBindings {
+  static CreateOfflineRecognizer? createOfflineRecognizer;
+  static DestroyOfflineRecognizer? destroyOfflineRecognizer;
+  static CreateOfflineStream? createOfflineStream;
+  static DestroyOfflineStream? destroyOfflineStream;
+  static AcceptWaveformOffline? acceptWaveformOffline;
+  static DecodeOfflineStream? decodeOfflineStream;
+  static GetOfflineStreamResultAsJson? getOfflineStreamResultAsJson;
+  static DestroyOfflineStreamResultJson? destroyOfflineStreamResultJson;
+
   static CreateOnlineRecognizer? createOnlineRecognizer;
 
   static DestroyOnlineRecognizer? destroyOnlineRecognizer;
@@ -611,6 +736,46 @@ class SherpaOnnxBindings {
   static SherpaOnnxFreeWave? freeWave;
 
   static void init(DynamicLibrary dynamicLibrary) {
+    createOfflineRecognizer ??= dynamicLibrary
+        .lookup<NativeFunction<CreateOfflineRecognizerNative>>(
+            'CreateOfflineRecognizer')
+        .asFunction();
+
+    destroyOfflineRecognizer ??= dynamicLibrary
+        .lookup<NativeFunction<DestroyOfflineRecognizerNative>>(
+            'DestroyOfflineRecognizer')
+        .asFunction();
+
+    createOfflineStream ??= dynamicLibrary
+        .lookup<NativeFunction<CreateOfflineStreamNative>>(
+            'CreateOfflineStream')
+        .asFunction();
+
+    destroyOfflineStream ??= dynamicLibrary
+        .lookup<NativeFunction<DestroyOfflineStreamNative>>(
+            'DestroyOfflineStream')
+        .asFunction();
+
+    acceptWaveformOffline ??= dynamicLibrary
+        .lookup<NativeFunction<AcceptWaveformOfflineNative>>(
+            'AcceptWaveformOffline')
+        .asFunction();
+
+    decodeOfflineStream ??= dynamicLibrary
+        .lookup<NativeFunction<DecodeOfflineStreamNative>>(
+            'DecodeOfflineStream')
+        .asFunction();
+
+    getOfflineStreamResultAsJson ??= dynamicLibrary
+        .lookup<NativeFunction<GetOfflineStreamResultAsJsonNative>>(
+            'GetOfflineStreamResultAsJson')
+        .asFunction();
+
+    destroyOfflineStreamResultJson ??= dynamicLibrary
+        .lookup<NativeFunction<DestroyOfflineStreamResultJsonNative>>(
+            'DestroyOfflineStreamResultJson')
+        .asFunction();
+
     createOnlineRecognizer ??= dynamicLibrary
         .lookup<NativeFunction<CreateOnlineRecognizerNative>>(
             'CreateOnlineRecognizer')