C#使用Vosk进行语音识别

最近进行语音识别的项目，由于受网络等因素的影响，找了下找到一个离线版本的语音识别Vosk，系统自带的语音识别效果比较差，百度和讯飞之类的需要通过网络进行识别，也需要费用

由于Vosk只有netstandard2.0版本，所以至少使用Framework4.6.1及以上版本兼容，

从https://alphacephei.com/vosk/models 下载模型，中文识别的，也可以通过自己训练模型得到

以下具体示例代码：

using NAudio.Wave;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Vosk;

namespace NAudioTest
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private Model model = new Model("modelcn");//程序根目录下

        private WaveIn waveIn;//WasapiLoopbackCapture 系统音频卡输出语音，我们使用外部输入语音

        private VoskRecognizer rec;

        private void InitRec()
        {
            waveIn = new WaveIn();//WasapiLoopbackCapture
            waveIn.WaveFormat = new WaveFormat(16000,16, 1);//44100 采样率16K就可以，太高会导致识别率下降，百度也使用16K
            waveIn.DataAvailable += WaveIn_DataAvailable;

            rec = new VoskRecognizer(model, waveIn.WaveFormat.SampleRate);//加载模型
            rec.SetMaxAlternatives(0);//设置备选项
            rec.SetWords(false);//设置是否显示时间
        }

        private void btnStart_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                if(waveIn != null)
                {
                    waveIn.StartRecording();
                }
                else
                {
                    InitRec();
                }
            }
            catch
            {
            }
        }

        private void WaveIn_DataAvailable(object sender, WaveInEventArgs e)
        {
            //int recLen = e.BytesRecorded;
            //byte[] data = new byte[recLen];
            //Array.Copy(e.Buffer, data, recLen);
            if (rec.AcceptWaveform(e.Buffer, e.BytesRecorded))
            {
                Console.WriteLine(rec.Result());
            }
            else
            {
                //Console.WriteLine(rec.FinalResult());//不要片段去分析，不然因为语义太少分析不出来
                //Console.WriteLine("---------");
            }
        }

        private void btnStop_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                if (waveIn != null)
                {
                    waveIn.StopRecording();
                }
            }
            catch
            {
            }
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            InitRec();
        }
    }
}

前面部分识别错误，后面都是正确的，还进行了语义分割

第二种方法

using System;
using System.IO;
using Vosk;

public class VoskDemo
{
   public static void DemoBytes(Model model)
   {
        // Demo byte buffer
        VoskRecognizer rec = new VoskRecognizer(model, 16000.0f);
        rec.SetMaxAlternatives(0);
        rec.SetWords(true);
        using(Stream source = File.OpenRead("test.wav")) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0) {
                if (rec.AcceptWaveform(buffer, bytesRead)) {
                    Console.WriteLine(rec.Result());
                } else {
                    Console.WriteLine(rec.PartialResult());
                }
            }
        }
        Console.WriteLine(rec.FinalResult());
   }

   public static void DemoFloats(Model model)
   {
        // Demo float array
        VoskRecognizer rec = new VoskRecognizer(model, 16000.0f);
        using(Stream source = File.OpenRead("test.wav")) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0) {
                float[] fbuffer = new float[bytesRead / 2];
                for (int i = 0, n = 0; i < fbuffer.Length; i++, n+=2) {
                    fbuffer[i] = BitConverter.ToInt16(buffer, n);
                }
                if (rec.AcceptWaveform(fbuffer, fbuffer.Length)) {
                    Console.WriteLine(rec.Result());
                } else {
                    Console.WriteLine(rec.PartialResult());
                }
            }
        }
        Console.WriteLine(rec.FinalResult());
   }

   public static void DemoSpeaker(Model model)
   {
        // Output speakers
        SpkModel spkModel = new SpkModel("model-spk");
        VoskRecognizer rec = new VoskRecognizer(model, 16000.0f);
        rec.SetSpkModel(spkModel);

        using(Stream source = File.OpenRead("test.wav")) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0) {
                if (rec.AcceptWaveform(buffer, bytesRead)) {
                    Console.WriteLine(rec.Result());
                } else {
                    Console.WriteLine(rec.PartialResult());
                }
            }
        }
        Console.WriteLine(rec.FinalResult());
   }

   public static void Main()
   {
        // You can set to -1 to disable logging messages
        Vosk.Vosk.SetLogLevel(0);

        Model model = new Model("model");
        DemoBytes(model);
        DemoFloats(model);
        DemoSpeaker(model);
   }
}