Joe Horn 的啟示錄

前陣子，在工作上剛好需要對 wav 檔案格式進行判定，可是 NAudio 製作出來的格式用來作判斷又有錯誤，所以土法煉鋼寫了一個小 class：

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

class WavInfo
{
    private String _Error;
    public String Error
    {
        get
        {
            return this._Error;
        }
    }

    private Boolean _PCM;
    public Boolean PCM
    {
        get
        {
            return this._PCM;
        }
    }

    private uint _Channel;
    public uint Channel
    {
        get
        {
            return this._Channel;
        }
    }

    private uint _SampleRate;
    public uint SampleRate
    {
        get
        {
            return this._SampleRate;
        }
    }

    private uint _BitsPerSample;
    public uint BitsPerSample
    {
        get
        {
            return this._BitsPerSample;
        }
    }

    private uint _ByteRate;
    public uint ByteRate
    {
        get
        {
            return this._ByteRate;
        }
    }

    private uint _BlockAlign;
    public uint BlockAlign
    {
        get
        {
            return this._BlockAlign;
        }
    }

    public WavInfo(String FileName)
    {
        try
        {
            FileStream FS = File.OpenRead(@FileName);
            Byte[] ReadTmp = new Byte[36];

            FS.Read(ReadTmp, 0, 36);
            FS.Close();

            if (BitConverter.ToUInt16(ReadTmp, 20) == 1)
            {
                this._PCM = true;
            }

            this._Channel = BitConverter.ToUInt16(ReadTmp, 22);
            this._SampleRate = BitConverter.ToUInt32(ReadTmp, 24);
            this._BitsPerSample = BitConverter.ToUInt16(ReadTmp, 34);

            this._ByteRate = this._Channel * this._SampleRate * this._BitsPerSample / 8;
            this._BlockAlign = this._Channel * this._BitsPerSample / 8;

            this._Error = String.Empty;
        }
        catch (Exception e)
        {
             this._Error = e.ToString();
        }
    }
}

• 檢查 Error 是否為空字串，就知道是否成功取得 wav 檔案資訊。
• 檢查 PCM 是否為 true，就知道該檔案是不是 PCM 格式的 wav 檔。
• wav 檔播放的時間會等於 ByteRate。

Technorati Tags: .NET, Audio, C#, file, NAudio, PCM, wav

(Visited 4839 times)

剛剛弄出來的東西.

DsExport.vb :

Public Class DsExport

  Public Shared Function Export(ByVal ds As DataSet, _
                                ByVal dtName As String, _
                                ByVal colList() As String, _
                                ByVal colValue() As Integer) As String
    Dim header As String = ""
    Dim body As String = ""
    Dim record As String = ""

    For Each col As String In colList
      header = header & Chr(34) & col & Chr(34) & ","
    Next
      header = header.Substring(0, header.Length - 1)

    For Each row As DataRow In ds.Tables(dtName).Rows
      Dim arr() As Object = row.ItemArray()

      For Each i As Integer In colValue
        If arr(i).ToString().IndexOf(",") > 0 Then
          record = record & Chr(34) & arr(i).ToString() & Chr(34) & ","
        Else
          record = record & arr(i).ToString() & ","
        End If
      Next

      body = body & record.Substring(0, record.Length - 1) & vbCrLf
      record = ""
    Next

    Return header & vbCrLf & body

  End Function

End Class

呼叫方式:

  Private Sub BtnExport_Click(ByVal sender As System.Object, _
                              ByVal e As System.EventArgs) Handles BtnExport.Click
    Dim colList() As String = {"CSV表頭1", "CSV表頭2", "CSV表頭3"}

    "顯示順序: SQL query 刮出來的欄位0, 4, 2
    Dim colValue() As Integer = {0, 4, 2}

    Dim strData As String = _
      DsExport.Export(DataSet 變數名稱, _
                      "DataSet 變數中的 DataTabel 名稱", _
                      colList, colValue)

    Dim binData() As Byte = System.Text.Encoding.Default.GetBytes(strData)

    Response.Clear()
    Response.AddHeader("Content-Type", "application/vnd.ms-access")
    Response.AddHeader("Content-Disposition", "inline;filename=檔案名稱.csv")
    Response.BinaryWrite(binData)
    Response.End()
  End Sub

Technorati Tags: .NET, CSV, DataSet, Visual Basic

(Visited 7639 times)