Hi,
I'm trying to measure the frequency of a sine given from a frequency-generator. The generator is connected to the PC via the audio-input.
I'm using a QAudioInput and a QIODevice to handle the data.
The frequency is measured by counting the zero-crossings in a defined time, this works until ~5khz.
I wonder, why the amplitude of the signal seems to lower with rising frequency:
Obove 5khz the data arriving in the QIODevice has values between 125 and 128, which makes it impossible, to count the zero-crossings correctly (It's normaly oscillating around 127).
The frequency generator does not lower the amplitude of the signal, i checked this with an oscilloscope.

Does somebody know, why QT seems to lower the amplitude?

Greetings