tflite_flutter 0.1.0

TensorFlow Lite dart API for Flutter.

TensorFlow Lite Flutter Plugin

TensorFlow Lite plugin provides a dart API for accessing TensorFlow Lite interpreter and performing inference. It binds to TensorFlow Lite C API using dart:ffi.

Initial setup

Add dynamic libraries to your app

The pre-built binaries can be found in release assets.

Place the script install.sh at the root of your project.

Run

sh install.sh

at the root of your project to automatically download and place binaries at appropriate folders.

The binaries installed will not include support for GpuDelegateV2 and NnApiDelegate however InterpreterOptions().useNnApiForAndroid can still be used.

Use install.sh -d instead if you wish to use these GpuDelegateV2 and NnApiDelegate.

The pre-built binaries are updated with each stable tensorflow release. However, you many want to use latest unstable tf releases or older tf versions, for that proceed to build locally.

How to build locally ?

Make sure you have required version of bazel installed. (Check TF_MIN_BAZEL_VERSION, TF_MAX_BAZEL_VERSION in configure.py)

• Android

Configure your workspace for android builds as per these instructions.

For TensorFlow >= v2.2

    bazel build -c opt --cxxopt=--std=c++11 --config=android_arm //tensorflow/lite/c:tensorflowlite_c
    
    // similarily for arm64 use --config=android_arm64

For TensorFlow <= v2.1

    bazel build -c opt --cxxopt=--std=c++11 --config=android_arm //tensorflow/lite/experimental/c:libtensorflowlite_c.so
    
    // similarily for arm64 use --config=android_arm64

• iOS

Refer instructions on TensorFlow Lite website to build locally for iOS.

Note: You must use macOS for building iOS.

Dependency

tflite_flutter: ^0.1.0

Import

import 'package:tflite_flutter_plugin/tflite.dart' as tfl;

Usage instructions

Creating the Interpreter

Interpreter can be created in three ways:

• directly from asset (easiest)

  Place your_model.tflite in assets directory. Make sure to include assets in pubspec.yaml.

  final interpreter = await tfl.Interpreter.fromAsset('your_model.tflite');
  

• from buffer

    final buffer = await getBuffer('assets/your_model.tflite');
    final interpreter = tfl.Interpreter.fromBuffer(buffer);
  
  Future<Uint8List> getBuffer(String filePath) async {  
   final rawAssetFile = await rootBundle.load(filePath);  
   final rawBytes = rawAssetFile.buffer.asUint8List();  
   return rawBytes;  
  }
  

• from file

  final dataFile = await getFile('assets/your_model.tflite');
  final interpreter = tfl.Interpreter.fromFile(dataFile);
    
  Future<File> getFile(String fileName) async {
    final appDir = await getTemporaryDirectory();
    final appPath = appDir.path;
    final fileOnDevice = File('$appPath/$fileName');
    final rawAssetFile = await rootBundle.load(fileName);
    final rawBytes = rawAssetFile.buffer.asUint8List();
    await fileOnDevice.writeAsBytes(rawBytes, flush: true);
    return fileOnDevice;
  }
  

Performing inference

• For single input and output

  Use void run(Object input, Object output).

  // For ex: if input tensor shape [1,5] and type is float32
  var input = [[1.23, 6.54, 7.81. 3.21, 2.22]];
  	
  // if output tensor shape [1,2] and type is float32
  var output = List(1*2).reshape([1,2]);
  
  // inference
  interpreter.run(input, output);
  	
  // print the output
  print(output);
  

• For multiple inputs and outputs

  Use void runForMultipleInputs(List<Object> inputs, Map<int, Object> outputs).

  var input0 = [1.23];  
  var input1 = [2.43];  
  	
  // input: List<Object>
  var inputs = [input0, input1, input0, input1];  
  	
  var output0 = List<double>(1);  
  var output1 = List<double>(1);
  	
  // output: Map<int, Object>   
  var outputs = {0: output0, 1: output1};
  	
  // inference  
  interpreter.runForMultipleInputs(inputs, outputs);
  	
  // print outputs
  print(outputs)
  

Closing the interpreter

interpreter.close();

Improve performance using delegate support

Note: This feature is under testing and could be unstable with some builds and on some devices.

• NNAPI delegate for Android

  var interpreterOptions = tfl.InterpreterOptions()..useNnApiForAndroid = true;
  final interpreter = await tfl.Interpreter.fromAsset('your_model.tflite',
      options: interpreterOptions);
    
  

  or

  var interpreterOptions = tfl.InterpreterOptions()..addDelegate(tfl.NnApiDelegate());
  final interpreter = await tfl.Interpreter.fromAsset('your_model.tflite',
      options: interpreterOptions);
        
  

• GPU delegate for Android and iOS

Refer Tests to see more example code for each method.

Refer Text Classification Flutter Example App for demo.

Credits

• Tian LIN, Jared Duke, Andrew Selle, YoungSeok Yoon, Shuangfeng Li from the TensorFlow Lite Team for their invaluable guidance.
• Authors of dart-lang/tflite_native.