[alsa-devel] wrong decibel data?

[Raymond Yau]

2010/4/8 Nicolo' Chieffo <nicolo.chieffo at gmail.com>

> I'm sorry but I found out that I gave you wrong values of "amixer -D
> pulse": I just discovered that when I lower the alsa master volume, in
> some occasions the PCM volume goes to 99%, so now I will put it to
> 100% and check the pulse volume again.
>
> 0 dB    =  65536 [100%]
> -3 dB   =  57520 [88%]
> -6 dB   =  52057 [79%]
> -12 dB =  41034 [63%]
> -24 dB =  26090 [40%]
> -48 dB = 10151 [15%]
>
> So again, the only problem is that -48 dB IS mute, but it's not
> declared as mute.
> This is the real issue.
>

For AC97 codec , both Master and PCM are hardware volume controls

Register 02 - control the stereo master volume
Register 18 - PCM out volume

But on HDA , PCM is most likely a software volume control just like
pulseaudio volume control