音频文件解析(一)：WAV格式文件头部解析

简介

　　WAV 为微软开发的一种声音文件格式，它符合 RIFF（Resource Interchange File Format）文件规范，用于保存 Windows 平台的音频信息资源。

第一节 文件头部格式

　　文件头（Header）是位于文件开头的一段承担一定任务的数据，通常是对主体数据的描述。

　　WAV 文件头由哪几部分构成

　　RIFF块（RIFF-Chunk）

　　格式化块（Format-Chunk）

　　附加块（Fact-Chunk）块偏移地址需要根据实际数据变更

　　数据块（Data-Chunk）块偏移地址需要根据实际数据变更

偏移地址	字节数	数据类型	内容
&H00	4	String	'RIFF'文件标志
&H04	4	UInteger	文件总长
&H08	4	String	'WAVE'文件标志

表1-1 RIFF块（RIFF-Chunk）

偏移地址	字节数	数据类型	内容
&H0C	4	String	'fmt'标志
&H10	4	UInteger	块长度
&H12	2	UShort	PCM格式类别
&H14	2	UShort	声道数目
&H18	4	UInteger	采样率
&H1C	4	UInteger	传输速率
&H1E	2	UShort	数据块对齐
&H20	2	UShort	每样本bit数
&H22	2	UShort	可选

表1-2 格式化块（Format-Chunk）

偏移地址	字节数	数据类型	内容
&H26	4	String	'fact'标志
&H2A	4	UInteger	块长度
&H2E	4	UInteger	附加信息

表1-3 附加块（Fact-Chunk）

偏移地址	字节数	数据类型	内容
&H32	4	String	'data'文件标志
&H36	4	UInteger	数据块总长

表1-4 数据块（Data-Chunk）

第二节 代码实现

　　1. 构建一个 WaveHeader 结构体

''' <summary>
''' wav音频头部信息
''' </summary>
Public Structure WaveHeader
#Region "RiffChunk"
    ''' <summary>
    ''' RIFF标志
    ''' </summary>
    Dim RIFF As String
    ''' <summary>
    ''' 文件长度
    ''' </summary>
    Dim FileSize As UInteger
    ''' <summary>
    ''' WAVE标志
    ''' </summary>
    Dim WAVE As String
#End Region
#Region "FormatChunk"
    ''' <summary>
    ''' FORMAT标志
    ''' </summary>
    Dim FORMAT As String
    ''' <summary>
    ''' Format长度
    ''' </summary>
    Dim FormatSize As UInteger
    ''' <summary>
    ''' 编码方式
    ''' </summary>
    Dim FilePadding As UShort
    ''' <summary>
    ''' 声道数目
    ''' </summary>
    Dim FormatChannels As UShort
    ''' <summary>
    ''' 采样频率
    ''' </summary>
    Dim SamplesPerSecond As UInteger
    ''' <summary>
    ''' 每秒所需字节数
    ''' </summary>
    Dim AverageBytesPerSecond As UInteger
    ''' <summary>
    ''' 数据块对齐单位
    ''' </summary>
    Dim BytesPerSample As UShort
    ''' <summary>
    ''' 单个采样所需Bit数
    ''' </summary>
    Dim BitsPerSample As UShort
    ''' <summary>
    ''' 附加信息
    ''' </summary>
    Dim FormatExtra As UShort
#End Region
#Region "FactChunk"
    ''' <summary>
    ''' FACT标志
    ''' </summary>
    Dim FACT As String
    ''' <summary>
    ''' Fact长度
    ''' </summary>
    Dim FactSize As UInteger
    ''' <summary>
    ''' Fact信息
    ''' </summary>
    Dim FactInf As UInteger
#End Region
#Region "DataChunk"
    ''' <summary>
    ''' DATA标志
    ''' </summary>
    Dim DATA As String
    ''' <summary>
    ''' Data长度
    ''' </summary>
    Dim DataSize As UInteger
#End Region
End Structure

VB.NET-WaveHeader

/// <summary>
/// wav音频头部信息
/// </summary>
public struct WaveHeader
{
    #region "RiffChunk"
    /// <summary>
    /// RIFF标志
    /// </summary>
    public string RIFF;
    /// <summary>
    /// 文件长度
    /// </summary>
    public uint FileSize;
    /// <summary>
    /// WAVE标志
    /// </summary>
        #endregion
    public string WAVE;
    #region "FormatChunk"
    /// <summary>
    /// FORMAT标志
    /// </summary>
    public string FORMAT;
    /// <summary>
    /// Format长度
    /// </summary>
    public uint FormatSize;
    /// <summary>
    /// 编码方式
    /// </summary>
    public ushort FilePadding;
    /// <summary>
    /// 声道数目
    /// </summary>
    public ushort FormatChannels;
    /// <summary>
    /// 采样频率
    /// </summary>
    public uint SamplesPerSecond;
    /// <summary>
    /// 每秒所需字节数
    /// </summary>
    public uint AverageBytesPerSecond;
    /// <summary>
    /// 数据块对齐单位
    /// </summary>
    public ushort BytesPerSample;
    /// <summary>
    /// 单个采样所需Bit数
    /// </summary>
    public ushort BitsPerSample;
    /// <summary>
    /// 附加信息
    /// </summary>
        #endregion
    public ushort FormatExtra;
    #region "FactChunk"
    /// <summary>
    /// FACT标志
    /// </summary>
    public string FACT;
    /// <summary>
    /// Fact长度
    /// </summary>
    public uint FactSize;
    /// <summary>
    /// Fact信息
    /// </summary>
        #endregion
    public uint FactInf;
    #region "DataChunk"
    /// <summary>
    /// DATA标志
    /// </summary>
    public string DATA;
    /// <summary>
    /// Data长度
    /// </summary>
        #endregion
    public uint DataSize;
}

C#-WaveHeader

　　2. 打开 *.wav 二进制文件

  Dim data() As Byte = My.Computer.FileSystem.ReadAllBytes(wavFileName)　

VB.NET-OpenFile

    byte[] data = System.IO.File.ReadAllBytes(wavFileName);

C#-OpenFile

　　3. 文件头部信息解析

    ''' <summary>
    ''' 返回指定字节数组包含的Wave头部信息
    ''' </summary>
    Public Function GetWaveHeaderFromBytes(data As Byte()) As WaveHeader
        Dim header As New WaveHeader
        Dim tempIndex As UShort =
        header.RIFF = CType(System.Text.Encoding.ASCII.GetChars(data, , ), String)
        header.FileSize = System.BitConverter.ToUInt32(data, )
        header.WAVE = CType(System.Text.Encoding.ASCII.GetChars(data, , ), String)
        'FormatChunk
        header.FORMAT = CType(System.Text.Encoding.ASCII.GetChars(data, , ), String)
        header.FormatSize = System.BitConverter.ToUInt32(data, )
        header.FilePadding = System.BitConverter.ToUInt16(data, )
        header.FormatChannels = System.BitConverter.ToUInt16(data, )
        header.SamplesPerSecond = System.BitConverter.ToUInt32(data, )
        header.AverageBytesPerSecond = System.BitConverter.ToUInt32(data, )
        header.BytesPerSample = System.BitConverter.ToUInt16(data, )
        header.BitsPerSample = System.BitConverter.ToUInt16(data, )
        If header.FormatSize =  Then
            header.FormatExtra = System.BitConverter.ToUInt16(data, )
        Else
            header.FormatExtra =
        End If
        tempIndex =  + header.FormatSize
        'FactChunk
        header.FACT = CType(System.Text.Encoding.ASCII.GetChars(data, tempIndex, ), String)
        If header.FACT = "fact" Then
            header.FactSize = System.BitConverter.ToUInt32(data, tempIndex + )
            header.FactInf = IIf(header.FactSize = , System.BitConverter.ToUInt16(data, tempIndex + ), System.BitConverter.ToUInt32(data, tempIndex + ))
            tempIndex = tempIndex + header.FactSize +
        Else
            header.FACT = "NULL"
            header.FactSize =
            header.FactInf =
        End If
        'DataChunk
        header.DATA = CType(System.Text.Encoding.ASCII.GetChars(data, tempIndex, ), String)
        header.DataSize = System.BitConverter.ToUInt32(data, tempIndex + )
        Return header
    End Function

VB.NET-GetWaveHeaderFromBytes

/// <summary>
/// 返回指定字节数组包含的Wave头部信息
/// </summary>
public WaveHeader GetWaveHeaderFromBytes(byte[] data)
{
    WaveHeader header = new WaveHeader();
    ushort tempIndex = ;
    header.RIFF = Convert.ToString(System.Text.Encoding.ASCII.GetChars(data, , ));
    header.FileSize = System.BitConverter.ToUInt32(data, );
    header.WAVE = Convert.ToString(System.Text.Encoding.ASCII.GetChars(data, , ));
    //FormatChunk
    header.FORMAT = Convert.ToString(System.Text.Encoding.ASCII.GetChars(data, , ));
    header.FormatSize = System.BitConverter.ToUInt32(data, );
    header.FilePadding = System.BitConverter.ToUInt16(data, );
    header.FormatChannels = System.BitConverter.ToUInt16(data, );
    header.SamplesPerSecond = System.BitConverter.ToUInt32(data, );
    header.AverageBytesPerSecond = System.BitConverter.ToUInt32(data, );
    header.BytesPerSample = System.BitConverter.ToUInt16(data, );
    header.BitsPerSample = System.BitConverter.ToUInt16(data, );
    if (header.FormatSize == ) {
        header.FormatExtra = System.BitConverter.ToUInt16(data, );
    } else {
        header.FormatExtra = ;
    }
    tempIndex =  + header.FormatSize;
    //FactChunk
    header.FACT = Convert.ToString(System.Text.Encoding.ASCII.GetChars(data, tempIndex, ));
    if (header.FACT == "fact") {
        header.FactSize = System.BitConverter.ToUInt32(data, tempIndex + );
        header.FactInf = (header.FactSize ==  ? System.BitConverter.ToUInt16(data, tempIndex + ) : System.BitConverter.ToUInt32(data, tempIndex + ));
        tempIndex = tempIndex + header.FactSize + ;
    } else {
        header.FACT = "NULL";
        header.FactSize = ;
        header.FactInf = ;
    }
    //DataChunk
    header.DATA = Convert.ToString(System.Text.Encoding.ASCII.GetChars(data, tempIndex, ));
    header.DataSize = System.BitConverter.ToUInt32(data, tempIndex + );
    return header;
}

C#-GetWaveHeaderFromBytes

附录

　　SoundPlayer 类 - MSDN