Hello Takashi, I do not completely understand the suggested test, do I just blindly follow your suggestions. I am sorry about the absence of more intelligent contributions from my side here. On Tue, Sep 05, 2006 at 11:36:50AM +0200, Takashi Iwai wrote: > > I tried the following. My amixer output is at the end of the mail for > > reference. first I created two shell scripts: > > > > -- s1.sh ------------------------------------------------------------- > > #! /bin/sh > > amixer set "PCM Capture Gain" 2 > > amixer set "PCM Capture Gain" 0 > > amixer set "PCM" 0 > > amixer set "PCM" 80% > > ---------------------------------------------------------------------- > > > > -- s2.sh ------------------------------------------------------------- > > #! /bin/sh > > amixer set "PCM Capture Gain" 0 > > amixer set "PCM Capture Gain" 2 > > amixer set "PCM" 0 > > amixer set "PCM" 80% > > ---------------------------------------------------------------------- > > > > and then I run the following command on the shell > > > > while true; do ./s1.sh; sleep 1; ./s2.sh; sleep 1; done > > > > While this was running I recorded a wav file with arecord. The volume > > of the recorded file was extremely low (is this normal?) so I > > normalised it with audacity. I looked at the wave form in audacity > > and I played the normalised file with alsamixer. > > In s2.sh, use a higher value for "PCM Capture Gain", such as 20. > If the volume is still low, then IPGA is not independent. I used 'amixer set "PCM Capture Gain" 20' now in s2.sh only. Was this the plan? Result: there is now an audible crack when s2.sh is executed, but the volume before and after the cracks still seems to be the same. I also tried something else: when I alternate between ---------------------------------------------------------------------- amixer set "PCM Capture Gain" 0 amixer set "PCM Capture Gain" 20 amixer set "PCM" 0 amixer set "PCM" 80% ---------------------------------------------------------------------- and ---------------------------------------------------------------------- amixer set "PCM" 0 amixer set "PCM" 80% amixer set "PCM Capture Gain" 0 amixer set "PCM Capture Gain" 20 ---------------------------------------------------------------------- the recording has alternating load and quiete stretches. Whatever this might tell us about the ADC, it looks like a bug to me: the order of setting the two controls shouldn't matter. Or am I confused again? I hope this helps, Jochen -- http://seehuhn.de/
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