Re: [Alsa-user] DC Offset on microphone input
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From: Bill U. <un...@ph...> - 2011-01-09 20:47:41
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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. |