[Stk] peaks in sin wave

[steffi at hoxel.org]

Hallo,

I have the following problem.
I record a 50Hz sin wave from an USB soundcard with RtWvIn in a wav  
file. Sometimes I get small peaks in the file, which come not from my  
input wave.
When the sin has positive gradient the peaks are negative and when the  
sin has negative gradient the peaks are positive.
For some reason the distance between those peaks equals the "period  
length" or multiple of that. With "period length" I mean the value I  
give to
RtWvIn :: RtWvIn( unsigned int nChannels, StkFloat sampleRate, int  
device, int          bufferFrames, int nBuffers )
in the variable "bufferFrames".
Sometimes my program runs three days without those peaks and then they  
appear for 20 minutes or something.
On an eee-pc with debian and ALSA version 1.0.16. this peaks appear  
quite often, while I have not seen them on my laptop with debian and  
ALSA version 1.0.12rc1.

Do you have any ideas?
Thank you, Stefanie Schmidt