Date: Tue, 18 Sep 2012 22:56:35 -0700 From: matt <sendtomatt@gmail.com> To: Doug Barton <dougb@FreeBSD.org> Cc: freebsd-current@FreeBSD.org Subject: Re: squealing/whistling audio Message-ID: <50595E93.9080908@gmail.com> In-Reply-To: <5059194F.4090002@FreeBSD.org> References: <5059194F.4090002@FreeBSD.org>
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On 09/18/12 18:01, Doug Barton wrote: > Sometime in the last couple of months an old problem has resurfaced on > HEAD, a sort of squealing/whistling sound in the audio, even without > anything playing. The sound is similar to the wind whistling through > something. > > Before I blindly go off on a bisecting spree, does anyone have a > suggestion as to where I might look? > > Doug > > Electrically that's usually oscillation (too high gain or too much electrical feedback) or an unshielded input. My guess would be that there is an input that is defined and active in software, but is a loose, ungrounded pin in real life. Like a second microphone input on the chip, but not actually connected, would be my guess. Can you try purging out nids that you don't use with loader tunables (set their as to 0)? Or sysctls as reboots aren't as necessary anymore with snd_hda? Maybe something changed in software that is seeing inputs that were not present. Also just try muting all inputs with mixer... Just a guess, but when I hear squealing/whistling/howling I think "analog" before I think "digital"... Matt
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