Getting time length of a .wav song

[kataruna]

I have some songs in the resources of my application and want to get their time length so that I can set a timer to tick when the song ends. And then start the next song. I want to do that in my code, and get the time length of a song as an integer value.

I have been googling for it for many hours. I'm a beginner. So please try to explain in a simple language. Thanks in advance.

[cicatrix]

There are two ways, a hard way (path of light) and an easy way (path of darkness).

The hard way:
Parse the header of your wav using this information:
https://ccrma.stanford.edu/courses/4...ts/WaveFormat/

Now, the Dark side way (using MCI):

Imports System.Runtime.InteropServices
 
Public Class MCI
 
    <DllImport("winmm", setlasterror:=True, entrypoint:="mciSendString", CharSet:=CharSet.Auto)> _
    Private Shared Function mciSendString( _
            ByVal lpstrCommand As String, _
            ByVal lpstrReturnString As String, _
            ByRef uReturnLength As Integer, _
            ByVal hwndCallBack As IntPtr) As Integer
    End Function
 
    Public Shared Function GetMediaLength(ByVal FileName As String) As ULong
 
        Dim MediaLength As ULong
        Dim RetString As New String(" "c, 50)
        Dim CommandString As String
 
        'open the media file
        If Not IO.File.Exists(FileName) Then
            Throw New IO.FileNotFoundException(String.Format("File {0} was not found.", FileName))
            Return Nothing
        End If
 
        CommandString = "Open " & FileName & " alias MediaFile"
        mciSendString(CommandString, String.Empty, 0, IntPtr.Zero)
 
        'get the media file length
        CommandString = "Set MediaFile time format milliseconds"
        mciSendString(CommandString, String.Empty, 0, IntPtr.Zero)
        CommandString = "Status MediaFile length"
 
        mciSendString(CommandString, RetString, RetString.Length, IntPtr.Zero)
 
        RetString = RetString.Trim
 
        If Not ULong.TryParse(RetString, MediaLength) Then
            MsgBox(String.Format("Failed to retrieve the media length for '{0}'.", FileName))
            Return Nothing
        End If
 
        'close the media file
        CommandString = "Close MediaFile"
        mciSendString(CommandString, vbNullString, 0, IntPtr.Zero)
        Return MediaLength
    End Function
End Class

Usage:

MCI.GetMediaLength(filename) ' The return value will be in milliseconds.

By the way this same function also works with all media formats supported by MCI (Media Control Interface)
http://en.wikipedia.org/wiki/Media_Control_Interface

[TETYYS]

dark side is better

[kataruna]

Wow! What a complication! I didn't understand neither of the ways. I copied and pasted the dark way. And used the MCI like this:

Timer3.Interval = MCI.GetMediaLength(music(0))

It gave me an error pointing to that line and saying:

InvalidCastException was unhandled

Converting from type "UnmanagedMemoryStream" to type "String" is invalid.

What's the problem? I'm a beginner and I don't get it. Visual Basic is supposed to have easier ways for stuff like that.

[cicatrix]

You should provide a filename to it, not stream.

[kataruna]

After some struggle I got it working. Thanks. Visual Basic should have had simpler ways of doing such stuff.

[MathImagics]

Just for the record, the so-called "hard way" isn't hard at all. In the header is a value, BytesPerSecond and we just divide this into the filesize (also in the header).

The following code is VB6, but perhaps someone would be kind enough to convert it to VB.NET.

Type RIFFHEADER
   RIFFtag        As String * 4  ' "RIFF"
   Filesize       As Long
   WAVtag         As String * 4  ' "WAVE"
   FMTtag         As String * 4  ' "fmt "
   FMTsize        As Long
   CompressType   As Integer
   Channels       As Integer
   SampleRate     As Long        ' Samples per sec
   BytesPerSec    As Long        ' = SampleRate * BytesPerSample
   BytesPerSample As Integer
   BitsPerSample  As Integer
   End Type
   
Dim WAVHEADER As RIFFHEADER

Function WavLength(ByVal wName As String) As Long ' length in seconds
   Dim fv As Integer
   
   fv = FreeFile
   If Dir$(wName) = "" Then Exit Function   ' ensure we only open an existing file
   Open wName For Binary As fv
   Get #fv, 1, WAVHEADER
   Close #fv
   With WAVHEADER
      If .FMTtag <> "fmt " Then Exit Function
      WavLength = .Filesize \ .BytesPerSec
      End With
   End Function

[KrisKasprzak]

I too am trying to get the duration of a WAV file. The dark side MCI does not work for many of my WAV files. I'm not sure why, they play fine, and the Windows explorer seems to report a valid duration.

I tried the above VB6 stuff and it works perfectly. I've been trying to get it converted to vb.net but i'm struggling. I can't figure out how to create a data structure or read a data stream into that data structure.

Any one know?

[KrisKasprzak]

I got something simple working--no error checking but you get the point

Private Function GetDuration(ByVal filename As String) As Double

Dim rifftag(4) As Char
Dim Filesize As Long
Dim WAVtag(4) As Char
Dim FMTtag(4) As Char
Dim FMTsize As Long
Dim compresstype As Integer
Dim channels As Integer
Dim samplerate As Long
Dim bytespersec As Long
Dim bytespersample As Integer
Dim bitspersample As Integer
Dim wavlength As Double

Dim reader = New BinaryReader(File.Open(strFileName, FileMode.Open))


rifftag = reader.ReadChars(4)
Filesize = reader.ReadInt32
WAVtag = reader.ReadChars(4)
FMTtag = reader.ReadChars(4)
FMTsize = reader.ReadInt32
compresstype = reader.ReadInt16
channels = reader.ReadInt16
samplerate = reader.ReadInt32
bytespersec = reader.ReadInt32
bytespersample = reader.ReadInt16
bitspersample = reader.ReadInt16

wavlength = (Filesize / bytespersec) * 1000 ' return in milliseconds

reader.Close()

Return wavlength

End Function