Add a C# api for offline-recognizer of sherpa-onnx (#129)

csharp-api-examples/Utils/AudioHelper.cs

@@ -0,0 +1,67 @@
+using NAudio.Wave;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+/// <summary>
+/// audio processing
+/// Copyright (c)  2023 by manyeyes
+/// </summary>
+public class AudioHelper
+{
+    public static float[] GetFileSamples(string wavFilePath, ref TimeSpan duration)
+    {
+        if (!File.Exists(wavFilePath))
+        {
+            Trace.Assert(File.Exists(wavFilePath), "file does not exist:" + wavFilePath);
+            return new float[1];
+        }
+        AudioFileReader _audioFileReader = new AudioFileReader(wavFilePath);
+        byte[] datas = new byte[_audioFileReader.Length];
+        _audioFileReader.Read(datas, 0, datas.Length);
+        duration = _audioFileReader.TotalTime;
+        float[] wavdata = new float[datas.Length / sizeof(float)];
+        Buffer.BlockCopy(datas, 0, wavdata, 0, datas.Length);
+        return wavdata;
+    }
+
+    public static List<float[]> GetChunkSamplesList(string wavFilePath, ref TimeSpan duration)
+    {
+        List<float[]> wavdatas = new List<float[]>();
+        if (!File.Exists(wavFilePath))
+        {
+            Trace.Assert(File.Exists(wavFilePath), "file does not exist:" + wavFilePath);
+            wavdatas.Add(new float[1]);
+            return wavdatas;
+        }
+        AudioFileReader _audioFileReader = new AudioFileReader(wavFilePath);
+        byte[] datas = new byte[_audioFileReader.Length];
+        int chunkSize = 16000;// datas.Length / sizeof(float);
+        int chunkNum = (int)Math.Ceiling((double)datas.Length / chunkSize);
+        for (int i = 0; i < chunkNum; i++)
+        {
+            int offset = 0;
+            int dataCount = 0;
+            if (Math.Abs(datas.Length - i * chunkSize) > chunkSize)
+            {
+                offset = i * chunkSize;
+                dataCount = chunkSize;
+            }
+            else
+            {
+                offset = i * chunkSize;
+                dataCount = datas.Length - i * chunkSize;
+            }
+            _audioFileReader.Read(datas, offset, dataCount);
+            duration += _audioFileReader.TotalTime;
+            float[] wavdata = new float[chunkSize / sizeof(float)];
+            Buffer.BlockCopy(datas, offset, wavdata, 0, dataCount);
+            wavdatas.Add(wavdata);
+
+        }
+        return wavdatas;
+    }
+}