Hello Stewart, Andy,
... I discovered that
the reason that I was not seeing the linear change with amplitude that
I was expecting was because there is some sort of vogad action
in the microphone audio input. Does anyone know:
1) How to turn this off
2) If the same applies to the line input
I'd be glad if I knew. Had exactly the same annoying problem, using a
notebook with an ESS 1869 "audio drive" chip. Here, the AGC is active on all
inputs, but only in the 8 bit mode. As it decays in visible discrete steps, I
assume the audio is always sampled at full 16 bit depth, and the on-chip
firmware tries to optimize the dynamic range when scaling down to 8 bits.
My problem is that I don't know how to program the Windows interface, and
from the DOS-box, I can only adress the chip in its 8 bit SoundBlaster
compatible mode. I have even sent an email inquiry to ESS asking how to work
around the AGC, but never got any response from them.
73 de Markus, DF6NM
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