[Openal] Open Capture Device fails with "invalid argument"

[Stefan Kögel]

I am trying to capture microphone input using OpenAL.
Using ubuntu8.10 a very simple example always results in

"AL lib: alsa.c:564: set access failed: Invalid argument".

I use libopenal-dev 1:1.3.253-4ubuntu1.

Here is what I do:

#include <AL/al.h>
#include <AL/alc.h>

int main(int pArgc, char* pArgv[]){

   ALCcontext* Context = alcGetCurrentContext();
   ALCdevice* Device = alcGetContextsDevice(Context);

   if(alcIsExtensionPresent(Device,"ALC_EXT_CAPTURE")==AL_FALSE)
     return 0;

   ALCdevice *CaptureDevice=alcCaptureOpenDevice(NULL,
11025,AL_FORMAT_MONO16,11025);

   if(!CaptureDevice)
       return 0;

    return 1;
}

What can I do to fix this?

Thanks in advance.
Regards, Stefan