Basic DirectSound question

[Scott H]

I'm just starting to learn directaudio, and want to start off not with
playing a WAV, thats all too easy, I want to generate the waveform, so
to start off I'm trying to generate white noise, using the code below,
but its erroring with a "Index out of range" Exception on the line of
code inditcated:


Private DSdev As New Device
Private DSbuffer As SecondaryBuffer
Private IOstream As System.IO.Memor yStream


Now some code to make it happen:


DSdev.SetCooper ativeLevel(Me.H andle, CooperativeLeve l.Normal)
IOstream = New System.IO.Memor yStream(22000)

Dim x As Integer
For x = 1 To 20000
IOstream.WriteB yte(Int(Rnd() * 254))
Next

DSbuffer = New SecondaryBuffer (IOstream, DSdev) '<<<< ERROR

If Not DSbuffer Is Nothing Then DSbuffer.Play(0 ,
BufferPlayFlags .Default)

----------------------
Is this the right way to go about generating white noise?

Thanks in advance,
Scott

[Armin Zingler]

Re: Basic DirectSound question

"Scott H" <x@x.com> schrieb[color=blue]
> I'm just starting to learn directaudio, and want to start off not
> with playing a WAV, thats all too easy, I want to generate the
> waveform, so to start off I'm trying to generate white noise, using
> the code below, but its erroring with a "Index out of range"
> Exception on the line of code inditcated:
>
>
> Private DSdev As New Device
> Private DSbuffer As SecondaryBuffer
> Private IOstream As System.IO.Memor yStream
>
>
> Now some code to make it happen:
>
>
> DSdev.SetCooper ativeLevel(Me.H andle, CooperativeLeve l.Normal)
> IOstream = New System.IO.Memor yStream(22000)
>
> Dim x As Integer
> For x = 1 To 20000
> IOstream.WriteB yte(Int(Rnd() * 254))
> Next[/color]

IOstream.positi on = 0
[color=blue]
> DSbuffer = New SecondaryBuffer (IOstream, DSdev) '<<<< ERROR[/color]

This solves the index out of range exception. Despite, I get another
exception, here, that I can not solve with a lot debugging.

You should try the MDX group @
microsoft.publi c.win32.program mer.directx.man aged


Armin

[Scott H]

Re: Basic DirectSound question


Thanks for your help anyway, Its a step closer, I'll try the other
newsgroup.


On Sun, 19 Feb 2006 15:30:56 +0100, "Armin Zingler"
<az.nospam@free net.de> wrote:
[color=blue]
>IOstream.posit ion = 0
>[color=green]
>> DSbuffer = New SecondaryBuffer (IOstream, DSdev) '<<<< ERROR[/color]
>
>This solves the index out of range exception. Despite, I get another
>exception, here, that I can not solve with a lot debugging.
>
>You should try the MDX group @
>microsoft.publ ic.win32.progra mmer.directx.ma naged
>
>
>Armin[/color]

[Scott H]

Re: Basic DirectSound question

Success!
It seems alot of people get stuck there, I found a C# example,
converted it to VB and got lots of errors, so just "jigged" around
with it a bit, and finally got it going, playing 1 second of white
noise!!!

Here's the code, for Armin and anyone else who wants to do this.

'DEFINITIONS:
Private DSdev As New Device
Private DSbuffer As SecondaryBuffer
Private DSdes As BufferDescripti on
Private DSformat As WaveFormat

'CODE IN SOME SUB/FUNCTION
DSdev.SetCooper ativeLevel(Me.H andle, CooperativeLeve l.Normal)

'define the wave format
DSformat = New WaveFormat()
DSformat.BitsPe rSample = 8
DSformat.Channe ls = 1
DSformat.BlockA lign = 1
DSformat.Format Tag = WaveFormatTag.P cm
DSformat.Sample sPerSecond = 8000
DSformat.Averag eBytesPerSecond = DSformat.Sample sPerSecond *
DSformat.BlockA lign

'buffer description
DSdes = New BufferDescripti on(DSformat)
DSdes.BufferByt es = 3 * DSformat.Averag eBytesPerSecond

'create the buffer
DSbuffer = New
Microsoft.Direc tX.DirectSound. SecondaryBuffer (DSdes, DSdev)

'generate ramdom data (white noise)
Dim rawsamples(2205 0) As Byte
Dim rnd1 = New System.Random()

Dim i As Integer
For i = 0 To 22050
rawsamples(i) = rnd1.Next(255)
Next i

' load audio samples to secondary buffer
DSbuffer.Write( 0, rawsamples, LockFlag.Entire Buffer)

'play audio buffer
DSbuffer.Play(0 , BufferPlayFlags .Default)