[pulseaudio-discuss] Mic input volume controls

[Colin Guthrie]

'Twas brillig, and Kulikov, Vitaliy at 01/12/10 17:34 did gyre and gimble:
> Hello everybody,
> 
> I would like to add more details for issue #1. Just changing order of
> the capture and MIC volume controls in the path is not enough if those
> volumes have gain only ranges and the reason is that, AFAIK, currently
> PA adjusts requested volume to the higher HW volume step. But if we
> change it to lower HW step it should work just fine. Here is the example
> how that works. 


> Let's say we have 22.5 dB gain only range with the 1.5 dB steps for
> capture HW control and 40 dB gain only range with the 10 dB steps for
> MIC boost control. Now, for all volumes between 0 and 10 dB PA will keep
> MIC boost level at 0 dB (when it is first in the path) and set capture
> level to 1.5, 3, 4.5 etc levels. And when level reaches 10 dB, then MIC
> boost will be set at 10 dB and capture at 0 dB. For the requested levels
> between 10 and 20 db, MIC boost will be kept at 10 dB and capture level
> will take the difference and so on.

What you describe above is how PA currently works with regards to volume
changes. We use the alsa API with a +1 dir argument to various functions
e.g.

http://www.alsa-project.org/alsa-doc/alsa-lib/group___simple_mixer.html#gef9c6ce9deb46de7b5727dc9982dc6d6


So we will use "accurate or first above" this means that less
attenuation will be done if the accuracy cannot be performed exactly.

So no need to worry about this.

Col

-- 

Colin Guthrie
gmane(at)colin.guthr.ie
http://colin.guthr.ie/

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mageia Contributor [http://www.mageia.org/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]