Re: squealing/whistling audio

On 09/18/2012 23:17, matt wrote:
> On 09/18/12 23:00, Doug Barton wrote:
>> On 9/18/2012 10:56 PM, matt wrote:
>>> 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.
>> Sorry, I should have been more clear. This problem doesn't occur in
>> windows, or linux, and last time I checked, didn't occur in freebsd 8. I
>> have everything irrlevant zeroed out in mixer.
>>
>> Doug
>>
> It was worth a shot. It is possible that each OS (and version) is
> setting the associations up properly though except HEAD on your machine.
> Is it a laptop or a desktop board?

Desktop.

> Any difference in the nid configuration between freebsd 8 and HEAD?

No.

> Does changing any of the hw.snd sysctls (latency, exact rate, vpc_0db)
> have any effect on the sound?

It doesn't affect the squeal.

> http://freshbsd.org/commit/freebsd/r230551 might be worth a look.

Didn't help.

> I
> couldn't find anything newer that looked like it would have an effect.
> Their are some earlier commits around January that are dealing with
> signal gain that could also have an effect.
> 
> Otherwise, I'm not sure where else to look.

Thanks anyway.

Doug

-- 

    I am only one, but I am one.  I cannot do everything, but I can do
    something.  And I will not let what I cannot do interfere with what
    I can do.
			-- Edward Everett Hale, (1822 - 1909)