[pulseaudio-discuss] [PATCH 0/5] volume: Decrease PA_VOLUME_MAX to be < 2^31

Arun Raghavan arun.raghavan at collabora.co.uk
Sun Oct 10 03:30:29 PDT 2010

On Sun, 2010-10-10 at 10:46 +0100, Colin Guthrie wrote:
> I'd also like to expose a new constant in the headers called
> PA_VOLUME_OVERDRIVE (or similarly named) that represents +11dB and
> should be our generally recommended "overdrive" (aka software
> amplification > 100%) amount for volume control UIs.
> Currently gnome-volume-control allows up to PA_VOLUME_NORM*1.5 which is
> ~= +11dB via current mappings, which is one reason why we previously
> decided on +11dB as our overdrive amount. That said, other volume
> control UIs (pavucontrol, kmix and, surprisingly,
> gnome-volume-control-applet) only allow volumes up to PA_VOLUME_NORM, so
> the idea would be to allow them to go right up to PA_VOLUME_OVERDRIVE,
> and hopefully implement an appropriate use of colours and markers etc.
> to make it clear to the user that they may not want to go >100% or risk
> clipping.
> http://pulseaudio.org/wiki/WritingVolumeControlUIs#Colouredvolumesliders

Sounds reasonable. Although, independent of the rest of these changes,
I'd also like to propose that the max. s/w gain (i.e. PA_VOLUME_MAX) be
decreased from its current value (~289 dB now, ~271 dB with my change)
to something more reasonable, like ~20 dB.

I came to this conclusion the hard way - while testing these patches, I
managed to turn up the volume high enough to temporarily damage my
hearing (it was a sudden burst, and I got to the off switch in time, so
no permanent damage done, I hope).

I understand that some overdrive is useful in general, but are there any
objections to capping the max. to something like ~20 dB?


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