语音放大缩小

public class SpeakLouder
   {
       private  WavFormat _wavFormat=new WavFormat();   //文件格式
       private  byte[] _audioData;      //语音数据
       private  SpeechSynthesizer _speech; //文本转语音
       private  string _pb;//文本转语音参数

       /// <summary>
       /// 文本转语音的说话器
       /// </summary>
       public SpeechSynthesizer Speech
       {
           set { _speech = value; }
       }

       /// <summary>
       /// 说话器的帮助参数
       /// </summary>
       public string Prompt
       {
           set { _pb = value; }
       }


       /// <summary>
       /// 执行播放操作
       /// </summary>
       /// <param name="speech">文本转语音的说话对象</param>
       /// <param name="pb">文本转语音的speak参数</param>
       /// <param name="scale">语音放大倍数</param>
       public void Play(SpeechSynthesizer speech, string pb, double scale)
       {
           _speech = speech;
           _pb = pb;
           Analyze();
           WaveScale(scale);
           WriteWavFile();
       }

       #region Analyze 分析音频文件
       /// <summary>
       /// 分析音频文件
       /// </summary>
       private void Analyze()
       {
           MemoryStream _stream = null;
           BinaryReader br = null;
           try
           {
               //构造读取流
               _stream = new MemoryStream();
               _speech.SetOutputToWaveStream(_stream);
               _speech.Speak(_pb);

               br = new BinaryReader(_stream);

               _stream.Position = 22;
               _wavFormat.Channels = br.ReadInt16();
               _stream.Position = 24;
               _wavFormat.SampleRate = br.ReadInt32();
               _stream.Position = 28;
               _wavFormat.ByteRate = br.ReadInt32();
               _stream.Position = 34;
               _wavFormat.BitsPerSample = br.ReadInt16();
               _stream.Position = 44;
               int dataByteSize = (int)(_stream.Length - 44);
               _audioData = new byte[dataByteSize];
               _stream.Read(_audioData, 0, dataByteSize);
           }
           catch (Exception ex)
           {
               Akloger.Error("解析刷卡语音出错:" + ex);
           }
           finally
           {
               if (br != null)
               {
                   br.Close();
                   br.Dispose();
               }
               if (_stream != null)
               {
                   _stream.Close();
                   _stream.Dispose();
               }
           }
       }
       #endregion

       #region WriteWavFile 写文件
       /// <summary>
       /// 写文件
       /// </summary>
       /// <param name="wavFormat">文件格式</param>
       /// <param name="audioData">音频数据</param>
       /// <param name="startIndex">audioData数组开始索引位置</param>
       /// <param name="length">写入audioData数组长度</param>
       private void WriteWavFile()
       {
           MemoryStream fs = null;
           BinaryWriter bw = null;
           try
           {
               fs = new MemoryStream();
               bw = new BinaryWriter(fs);
               fs.Position = 0;
               bw.Write(new char[4] { 'R', 'I', 'F', 'F' });
               bw.Write((int)(_audioData.Length + 44 - 8));
               bw.Write(new char[8] { 'W', 'A', 'V', 'E', 'f', 'm', 't', ' ' });
               bw.Write((int)16);
               bw.Write((short)1);
               bw.Write((short)_wavFormat.Channels);
               bw.Write(_wavFormat.SampleRate);
               bw.Write((int)(_wavFormat.SampleRate * ((_wavFormat.BitsPerSample * _wavFormat.Channels) / 8)));
               bw.Write((short)((_wavFormat.BitsPerSample * _wavFormat.Channels) / 8));
               bw.Write((short)_wavFormat.BitsPerSample);
               bw.Write(new char[4] { 'd', 'a', 't', 'a' });
               bw.Write(_audioData.Length);
               bw.Write(_audioData, 0, _audioData.Length);

               //播放声音
               fs.Position = 0;
               SoundPlayer _player = new SoundPlayer();
               _player.Stream = null;
               _player.Stream = fs;
               _player.PlaySync();


           }catch (Exception ex)
           {
               Akloger.Error("保存刷卡语音出错:" + ex);
           }
           finally
           {
               if (bw != null)
               {
                   bw.Close();
                   bw.Dispose();
               }
               if (fs != null)
               {
                   fs.Close();
                   fs.Dispose();
               }
           }
       }
       #endregion

       #region WaveScale 放大音频音量
       /// <summary>
       /// 放大音频音量
       /// </summary>
       /// <param name="scale">音量放大倍数</param>
       private void WaveScale(double scale)
       {
           //总播放时间
           // long totalTime = _wavFile.PlayTime;

           //采样位数
           // 16 bit 纵坐标为采样系数 细化为 2^16= 65535份 16位二进制表示 [ 0000 0000 0000 0000 ]
           // 即为2Byte (每单位时间内产生 2Byte 的音频数据)

           int byteNumPerSample = _wavFormat.BitsPerSample / 8;

           //采样频率
           // 11025Hz 横坐标为采样频率 单位时间为: 1/11025 s
           //单位时间内产生的的音频数据大小为 2Byte * 11025Hz * 声道数

           //字节数组 音频数据
           byte[] audioDatas = _audioData;


           // i 的值为每次衰减处理时的 字节读取位置 (索引)
           for (int i = 0; i < audioDatas.Length; i += byteNumPerSample)
           {


               //单位时间内的字节数为1 即采用8bit采样位数  每次只需要对一个字节进行衰减
               if (byteNumPerSample == 1)
               {
                   //获取需要衰减的字节值
                   var audioData = (double)audioDatas[i];

                   var temp = audioData * 1;
                   if (temp < -32767.5)
                   {
                       temp = -32768;
                   }
                   else if (temp > (float)32766.5)
                   {
                       temp = 32767;
                   }
                   //进行衰减线性处理
                   byte changedAudioData = (byte)temp;

                   //对原来的值进行更改
                   audioDatas[i] = changedAudioData;
               }
               else if (byteNumPerSample == 2)
               {
                   //16bit 量化 每单位时间产生2Byte数据 因此取 2Byte 的数据进行衰减处理
                   byte[] audioData = new byte[2];
                   Array.Copy(audioDatas, i, audioData, 0, 2);

                   //单个样点幅值
                   double sample = 0;

                   //转换为整数进行线性处理
                   sample = (double)BitConverter.ToInt16(audioData, 0) * scale;
                   if (sample < -32767.5)
                   {
                       sample = -32768;
                   }
                   else if (sample > (double)32766.5)
                   {
                       sample = 32767;
                   }
                   //转换为字节存储
                   byte[] buffer = BitConverter.GetBytes(Convert.ToInt16(sample));
                   if (!BitConverter.IsLittleEndian)
                       Array.Reverse(buffer);

                   Array.Copy(buffer, 0, audioDatas, i, 2);
               }
           }
           _audioData = audioDatas;
       }
       #endregion

   }

   #region WavFormat 头文件信息
   /// <summary>
   /// WAV 文件格式
   /// </summary>
   public class WavFormat
   {
       /// <summary>
       /// 采样位数
       /// </summary>
       public int BitsPerSample;
       /// <summary>
       /// 声道数
       /// </summary>
       public int Channels;
       /// <summary>
       /// 采样率
       /// </summary>
       public int SampleRate;
       /// <summary>
       /// 传输速率(播放速率)
       /// </summary>
       public long ByteRate;
   }
   #endregion