如何使用J2ME从音频文件创建波形显示

Question

我是J2ME的初学者，希望开发一个嵌入了波形显示的移动音乐编辑器作为我的项目。

有没有人可以帮助我，或给我一些教程如何将音频文件编码为波形显示？

Answer 1

这将使用n音讯生成的音频文件波形...

using NAudio.Wave; 
using System; 
using System.Collections.Generic; 
using System.Drawing; 
using System.IO; 
using System.Linq; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

public partial class test : System.Web.UI.Page 
{ 
    protected void Page_Load(object sender, EventArgs e) 
    { 
    string strPath = Server.MapPath("audio/060.mp3"); 
    string SongID = "2"; 
    byte[] bytes = File.ReadAllBytes(strPath); 
    WriteToFile(SongID,strPath, bytes); 
    Response.Redirect("Main.aspx"); 
    } 

private void WriteToFile(string SongID, string strPath, byte[] Buffer) 
{ 
    try 
    { 
     int samplesPerPixel = 128; 
     long startPosition = 0; 
     //FileStream newFile = new FileStream(GeneralUtils.Get_SongFilePath() + "/" + strPath, FileMode.Create); 
     float[] data = FloatArrayFromByteArray(Buffer); 

     Bitmap bmp = new Bitmap(1170, 200); 

     int BORDER_WIDTH = 5; 
     int width = bmp.Width - (2 * BORDER_WIDTH); 
     int height = bmp.Height - (2 * BORDER_WIDTH); 

     NAudio.Wave.Mp3FileReader reader = new NAudio.Wave.Mp3FileReader(strPath, wf => new NAudio.FileFormats.Mp3.DmoMp3FrameDecompressor(wf)); 
     NAudio.Wave.WaveChannel32 channelStream = new NAudio.Wave.WaveChannel32(reader); 

     int bytesPerSample = (reader.WaveFormat.BitsPerSample/8) * channelStream.WaveFormat.Channels; 

     using (Graphics g = Graphics.FromImage(bmp)) 
     { 

      g.Clear(Color.White); 
      Pen pen1 = new Pen(Color.Gray); 
      int size = data.Length; 

      string hexValue1 = "#009adf"; 
      Color colour1 = System.Drawing.ColorTranslator.FromHtml(hexValue1); 
      pen1.Color = colour1; 

      Stream wavestream = new NAudio.Wave.Mp3FileReader(strPath, wf => new NAudio.FileFormats.Mp3.DmoMp3FrameDecompressor(wf)); 

      wavestream.Position = 0; 
      int bytesRead1; 
      byte[] waveData1 = new byte[samplesPerPixel * bytesPerSample]; 
      wavestream.Position = startPosition + (width * bytesPerSample * samplesPerPixel); 

      for (float x = 0; x < width; x++) 
      { 
       short low = 0; 
       short high = 0; 
       bytesRead1 = wavestream.Read(waveData1, 0, samplesPerPixel * bytesPerSample); 
       if (bytesRead1 == 0) 
        break; 
       for (int n = 0; n < bytesRead1; n += 2) 
       { 
        short sample = BitConverter.ToInt16(waveData1, n); 
        if (sample < low) low = sample; 
        if (sample > high) high = sample; 
       } 
       float lowPercent = ((((float)low) - short.MinValue)/ushort.MaxValue); 
       float highPercent = ((((float)high) - short.MinValue)/ushort.MaxValue); 
       float lowValue = height * lowPercent; 
       float highValue = height * highPercent; 
       g.DrawLine(pen1, x, lowValue, x, highValue); 

      } 
     } 

     string filename = Server.MapPath("image/060.png"); 
     bmp.Save(filename); 
     bmp.Dispose(); 

    } 
catch (Exception e) 
    { 

    } 
} 
public float[] FloatArrayFromStream(System.IO.MemoryStream stream) 
{ 
    return FloatArrayFromByteArray(stream.GetBuffer()); 
} 

public float[] FloatArrayFromByteArray(byte[] input) 
{ 
    float[] output = new float[input.Length/4]; 
    for (int i = 0; i < output.Length; i++) 
    { 
     output[i] = BitConverter.ToSingle(input, i * 4); 
    } 
    return output; 
} 

}