using NAudio.Wave;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace XXX.util
{
    public static class WavFileUtils
    {
        /// <summary>
        /// 基于NAudio工具對Wav音頻文件剪切（限PCM格式）
        /// </summary>
        /// <param name="inPath">目標文件</param>
        /// <param name="outPath">輸出文件</param>
        /// <param name="cutFromStart">開始時間</param>
        /// <param name="cutFromEnd">結(jié)束時間</param>
        public static void TrimWavFile(string inPath, string outPath, TimeSpan cutFromStart, TimeSpan cutFromEnd)
        {
            using (WaveFileReader reader = new WaveFileReader(inPath))
            {
                int fileLength = (int)reader.Length;using (WaveFileWriter writer = new WaveFileWriter(outPath, reader.WaveFormat))
                {
                    float bytesPerMillisecond = reader.WaveFormat.AverageBytesPerSecond / 1000f;
                    int startPos = (int)Math.Round(cutFromStart.TotalMilliseconds * bytesPerMillisecond);
                    startPos = startPos - startPos % reader.WaveFormat.BlockAlign;
                    int endPos = (int)Math.Round(cutFromEnd.TotalMilliseconds * bytesPerMillisecond);
                    endPos = endPos - endPos % reader.WaveFormat.BlockAlign;
                    //判斷結(jié)束位置是否越界
                    endPos = endPos > fileLength ? fileLength : endPos;
                    TrimWavFile(reader, writer, startPos, endPos);
                }
            }
        }

        /// <summary>
        /// 重新合并wav文件
        /// </summary>
        /// <param name="reader">讀取流</param>
        /// <param name="writer">寫入流</param>
        /// <param name="startPos">開始流</param>
        /// <param name="endPos">結(jié)束流</param>
        private static void TrimWavFile(WaveFileReader reader, WaveFileWriter writer, int startPos, int endPos)
        {
            reader.Position = startPos;
            byte[] buffer = new byte[1024];
            while (reader.Position < endPos)
            {
                int bytesRequired = (int)(endPos - reader.Position);
                if (bytesRequired > 0)
                {
                    int bytesToRead = Math.Min(bytesRequired, buffer.Length);
                    int bytesRead = reader.Read(buffer, 0, bytesToRead);
                    if (bytesRead > 0)
                    {
                        writer.Write(buffer, 0, bytesRead);
                    }
                }
            }
        }
    }
}

調(diào)用：

string filePath = "D:\\wav\\test.wav";//需要切割的文件路徑
int cutTimeSpan = 20;//切割的時間片段時間（秒）
FileInfo fi = new FileInfo(filePath);
//獲取錄音文件時長（秒）
int fileTime = (int)Util.Cover(Util.GetVoiceTime(filePath)) / 1000;
//計算文件需要切割多少等份
decimal fileNum = Math.Ceiling((decimal)fileTime / cutTimeSpan);
int i = 0;
while (i < fileNum)
{
    string nowTime = Util.GetTimeStamp();//當前時間戳
    //切割后保存的文件絕對地址
    var outputPath = System.IO.Path.Combine(fi.Directory.FullName, string.Format("{0}_{1}{2}", fi.Name.Replace(fi.Extension, ""), nowTime, fi.Extension));
    //切割的開始時間
    TimeSpan cutFromStart = TimeSpan.FromSeconds(i * cutTimeSpan);
    //切割的結(jié)束時間
    TimeSpan cutFromEnd = cutFromStart + TimeSpan.FromSeconds(cutTimeSpan);
    //音頻切割
    WavFileUtils.TrimWavFile(recordFile.FilePath, outputPath, cutFromStart, cutFromEnd);
    i++;
}

Util 類：

using Shell32;
using System;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
using System.Threading;
using System.Windows.Forms;

namespace XXX.util
{
    class Util
    {
        /// <summary>
        /// 獲取時間戳
        /// </summary>
        /// <returns></returns>
        public static string GetTimeStamp()
        {
            TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
            return Convert.ToInt64(ts.TotalMilliseconds).ToString();
        }

        /// <summary>
        /// 返回音頻時長
        /// </summary>
        /// <param name="SongPath">音頻文件路徑</param>
        /// <returns></returns>
        public static string GetVoiceTime(string SongPath)
        {
            string dirName = Path.GetDirectoryName(SongPath);
            string SongName = Path.GetFileName(SongPath);
            ShellClass sh = new ShellClass();
            Folder dir = sh.NameSpace(dirName);
            FolderItem item = dir.ParseName(SongName);
            string SongTime = Regex.Match(dir.GetDetailsOf(item, -1), "\\d:\\d{2}:\\d{2}").Value;//返回音頻時長
            return SongTime;
        }

　　　   /// <summary>
        /// 時間格式轉(zhuǎn)毫秒值
        /// </summary>
        /// <param name="time">時間字符串</param>
        /// <returns></returns>
        public static long Cover(string time)
        {
            string[] a = time.Split(':');
            if (long.Parse(a[0]) == 0 && long.Parse(a[1]) == 0)
            {
                return long.Parse(a[2]) * 1000;
            }
            else if (long.Parse(a[0]) == 0 && long.Parse(a[1]) != 0)
            {
                return (long.Parse(a[1]) * 60 + long.Parse(a[2])) * 1000;
            }
            else if (long.Parse(a[0]) != 0 && long.Parse(a[1]) == 0)
            {
                return ((long.Parse(a[0]) * 60 * 60) + long.Parse(a[2])) * 1000;
            }
            else if (long.Parse(a[0]) != 0 && long.Parse(a[1]) != 0)
            {
                return (((long.Parse(a[0]) * 60) + long.Parse(a[1])) * 60) * 1000;
            }
            return 0;
        }
    }
}