[RESOLVED] Use of variables in Activex8 sound API to set Constants.

[camoore]

I am trying to write code using the ActiveX8 reference to generate short bursts of sound through my speaker at a FREQ(in Hz) and for a dur(ation) (in secs.). Parameters are specified at Option Explicit as constants.

The routine works 100% if I write code which specifies these parameters : eg.

Const FREQ = 500 'means 500 Hz
Const dur = 0.2 'means 200 milliseconds

So far, so good. But now I wish to have the VB6 program vary these parameters. For example, I would like to dim an integer variable named MYFREQ and be able to write Const FREQ = MYFREQ. However this fails. I get the error message "Assignment to Constant not permitted".

How can I reset, in software, the value of an API Const to the instantaneous value of a variable? Does the variable need to be Dim'd as a special type? How to assign a new value to a Constant in software?

Suggestions gratefully requested.

camoore

Wales
UK

[LaVolpe]

a CONST declaration simply means it doesn't change, ever.

In your routine that plays the sounds, pass the desired frequency & duration as variables that default to 500 & .02 respectively. Maybe something like this...

Public Sub PlayTheSound(Optional ByVal Frequency As Long, Optional ByVal Duration as Double) ' or should Double be Single?
      CONST FREQ = 500
      CONST dur = 0.2

       If Frequency = 0 The Frequency = FREQ
       If Duration = 0 then Duration = dur
 
       ' now use Frequency & Duration variables instead of the constants

End Sub

[camoore]

Thank you, La Volpe, for your suggestions. I have just started to try to understand ActiveX8 and its applications to the import and export of sound. At first sight, it is a very complex affair - but lots of things are thus at first encounter. Thanks to your suggestions, I have managed to get over the limitations apparently imposed by the use of Const declarations.

I have many more queries about VB6 interfacing with audio via ActiveX8, but these must be a learning curve for me and not an ever-extending thread here.

I found this forum thread, which is a tutorial about VB6 - audio interfacing bothways. At first reading, it seems most comprehensive but somewhat "over my head". However I mention it below in case it might be of assistance to other members reading this thread.

http://www.vbforums.com/showthread.php?t=388562

I shall mark this thread of mine as resolved, and thanks again for your prompt reply.

camoore

Wales
UK

[dilettante]

Oh you mean DirectX 8.

[camoore]

Yes, my apologies for the incorrect reference. That goes to show how new I am to this audio interfacing aspect of VB6 (and to many other aspects of it!).

My application is to write an automated morse code sender. which is now going along OK. Subsequently I wish to try to write an automated morse decoder - which will obviously involve the import rather than the export of audio signals.

camoore

Wales
UK