On Sun, 9 Jan 2011, Peter Nelson wrote:
> On Sun, 2011-01-09 at 17:55 +0200, Sergei Steshenko wrote:
>
>> Why do you think your ADC converts from DC ? I.e. why do you think you
>> have the DC offset in your recording ?
>>
>> Regards,
>> Sergei.
>>
>
> In my case, with two Intel "HDA" devices, there is an offset to the
> recorded values which varies with the input gain selected in alsa mixer.
> Perhaps not technically a "DC offset", as it might just be in the
> digital domain, it's still a fixed offset that can upset various things.
>
Again, if it bothers you, filter it out.
xs=0
while (input){
xs=.01 xinput +.99 xs
xoutput=xinput-xs
}
(This averages over roughly the last 100 inputs and subtracts the offset). If
you want a longer averaging, change the coefficients.
Tell us why it bothers you? And if it really keeps bothering you, buy a better
sound card.
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