[pulseaudio-discuss] Sound output is muted at 16% volume

[Colin Guthrie]

'Twas brillig, and Marti Raudsepp at 11/04/10 21:06 did gyre and gimble:
> Hi list,
> 
> I gave PulseAudio a try and it seems to be working fine so far
> 
> There is a small problem with volume controls. When I reduce the PA
> volume control below 16%, then volume is muted entirely. Apparently
> this happens because the ALSA "Master" control reaches 0%, which mutes
> all sound output on my hardware (even though the ALSA "mute" flag is
> not set). This seems hardware-specific, as I haven't seen this
> behavior on any other computers; usually 0% volume still outputs some
> level of sound.
> 
> I tried with kernels 2.6.32 and 2.6.33, PA 0.9.21, ALSA 1.0.21.
> 
> The sound chip according to ALSA is SigmaTel STAC9205 using the HDA driver
> 
> according to lspci:
> 00:1b.0 Audio device [0403]: Intel Corporation 82801H (ICH8 Family) HD
> Audio Controller [8086:284b] (rev 02)
> 
> I tried working around this by changing the PCM level in alsamixer,
> but whenever a new client connects, PulseAudio thinks it's smarter
> than me and resets the PCM mixer -- to somewhere between 0.00 ...
> -0.60 dB (?!), and sets the master level to 0% again
> 
> So there are 2 distinct problems:
> 1. The STAC9205  0% volume quirk needs to be handled somewhere
> 2. If PulseAudio wants to maximize some volume controls, it should set
> them at 0.0 dB, not -0.60 dB

This is generally caused by the driver exposing bad decibel information.

http://pulseaudio.org/wiki/BadDecibel

There is actually a discussion about this on the alsa-devel ML right now
concerning a similar chip and I suspect it's the same problem (I also
see it here).

We're basically waiting for Lennart to comment as the other main
contributor Raymond only really ever creates confusion - although he
does make some valid points, which means they have to be given respect
and answered properly. Lennart is aware of the thread and will be
replying in due course once he's cleared his plate a bit. I'll try and
remember and post back here when some resolution is reached.

Col


-- 

Colin Guthrie
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http://colin.guthr.ie/

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