Re: [gentoo-user] Advice Needed: Conexant HD-Audio noisy audio

[Michael Mol]

On Tue, May 15, 2012 at 3:29 PM, Ignas Anikevicius
<anikevicius@×××××.com> wrote:
> On 15/05/12 20:08, Michael Mol wrote:
>> There are going to be multiple sliders which affect your playback
>> volume. Without seeing a list of your sliders, I couldn't really guess
>> which, beyond 'Master', 'PCM' and 'Headphone'. There may be others; my
>> old Sound Blaster Live had a ton of internal signal processing
>> sliders, and anything that involves amplification presents that risk.
>
> [...] (some useful stuff snipped :))
>
> At the moment all the other sliders are at 0. So I do not know, maybe
> some other sliders are doing this...

Not if they're at their minimum settings. :-|

>
> Also, ALSA can show the levels in dBs for my card... but I get sand even
> when I'am at gain of ~ (-11,-14)dB on all three sliders (Master, PCM,
> Headphone).
>
>> You might try using something like PulseAudio, which may be doing
>> internal mixing in the floating point space before it maps back to
>> 16-bit linear PCM. My experiences with PulseAudio have generally been
>> positive in terms of audio quality. The trickiest part is getting
>> applications to pipe their audio through it, followed by getting
>> direct access to the card's mixer settings if I need it. But
>> "pavucontrol" as a mixer control for PulseAudio works reasonably well
>> for the majority of circumstances.
>
> I am using Pulse :)... The problem with I have that it changes my PCM
> and Headphone levels without asking me... Therefore, if I change the
> levels manually on alsamixer and then use Pavucontrol, it just changes
> the PCM and headphone or speaker levels to max, which makes the sound
> crappy. Otherwise I am quite a happy Pulse user. :)

Run alsamixer in a terminal while playing with pavucontrol; you'll see
Alsamixer update live while Pulse tweaks ALSA's mixer settings. It's
useful if you want to get a feel for what exactly Pulse is doing.

On my desktop system, I found that if I had the Pulse master volume
control set to about 70%, Pulse would have my various sliders set to
just about their maximum setting before I started getting clipping
noises.
>
> Is there a way to set the limiting thresholds?

No; the limiting thresholds I was describing are some value that just
happens to be what it is because of the way your sound card mixes
audio together.

> Or maybe I am using two
> things at the same (ALSA and Pulse) and they are clashing and,
> therefore, I can not get good quality sound?

Pulse is usually OK at managing ALSA in the background; you just have
to do all your volume tweaking through pavucontrol if you intend for
things to not change on you.

[snip]

>> (Note: I CC'd this back to the main list, because somehow this one got
>> sent to me directly. Channeling communications through the main list
>> keeps the archives useful.)
>
> I thought, that I have replied to both, list and you.. :) Well, thanks
> for that. :)

Might have been a quirk in my GMail interface, now that I look at it.
Your earlier email looks fine. Something about the list's distribution
pattern changed, so simply clicking "Reply" doesn't work; I now have
to click "Reply All".

Anyway, I'd try taking others' suggestions, too, and possibly poking
whatever PulseAudio support groups exist. They'll be interested in
your circumstance. If it's possible to use Pulse reasonably on your
hardware, they'll want to figure out how to make that less difficult
to do.

Also, Mark noted that there were sliders he hadn't tweaked before when
he was experiencing similar issues, and it's plausible Pulse isn't
poking those at all. Try watching alsamixer to see what Pulse is up
to, and see if Pulse is passing over some of those sliders.

-- 
:wq