Comment 22 for bug 1200925

The calculation of the dB value depends on whether you are working with amplitude values or power values. For power values, the formula is 10·log10(x), with x the relative power. For amplitude values, the formula is 20·log10(x).

for DAC

log10(0.006) = -2.2218

refer to 5. FUNCTION BLOCK DIAGRAM OF CM106-F+/L+

step 0 ~ 37
volume is 0 ~ -45dB

8.2 ADC VOLUME CONTROL

step 0 ~ 15
0 ~ 22.5 dB

8.3 MIC / LINE-IN MONITOR VOLUME CONTROL

step 0 ~ 31
-33 ~ 12 dB

USB Mixer: usb_id=0x0d8c0006, ctrlif=0, ctlerr=0
Card: USB Audio at usb-0000:00:1d.1-1, full speed
  Unit: 2
    Control: name="PCM Capture Volume", index=0
    Info: id=2, control=2, cmask=0x3, channels=2, type="S16"
    Volume: min=0, max=4095, dBmin=0, dBmax=1599
  Unit: 7
    Control: name="PCM Capture Source", index=0
    Info: id=7, control=0, cmask=0x0, channels=1, type="U8"
    Volume: min=1, max=4, dBmin=0, dBmax=0
  Unit: 8
    Control: name="Auto Gain Control", index=0
    Info: id=8, control=7, cmask=0x0, channels=1, type="BOOLEAN"
    Volume: min=0, max=1, dBmin=0, dBmax=0
  Unit: 8
    Control: name="Mic Capture Volume", index=0
    Info: id=8, control=2, cmask=0x3, channels=2, type="S16"
    Volume: min=0, max=4095, dBmin=0, dBmax=1599
  Unit: 9
    Control: name="Mic Playback Volume", index=0
    Info: id=9, control=2, cmask=0x3, channels=2, type="S16"
    Volume: min=0, max=8191, dBmin=0, dBmax=3199
  Unit: 9
    Control: name="Mic Playback Switch", index=0
    Info: id=9, control=1, cmask=0x0, channels=1, type="INV_BOOLEAN"
    Volume: min=0, max=1, dBmin=0, dBmax=0
  Unit: 11
    Control: name="Line Playback Volume", index=0
    Info: id=11, control=2, cmask=0x3, channels=2, type="S16"
    Volume: min=0, max=8191, dBmin=0, dBmax=3199
  Unit: 11
    Control: name="Line Playback Switch", index=0
    Info: id=11, control=1, cmask=0x0, channels=1, type="INV_BOOLEAN"
    Volume: min=0, max=1, dBmin=0, dBmax=0
  Unit: 13
    Control: name="Speaker Playback Volume", index=0
    Info: id=13, control=2, cmask=0x0, channels=1, type="S16"
    Volume: min=0, max=37, dBmin=0, dBmax=14
  Unit: 13
    Control: name="Speaker Playback Switch", index=0
    Info: id=13, control=1, cmask=0x0, channels=1, type="INV_BOOLEAN"
    Volume: min=0, max=1, dBmin=0, dBmax=0
  Unit: 15
    Control: name="Line Capture Volume", index=0
    Info: id=15, control=2, cmask=0x3, channels=2, type="S16"
    Volume: min=0, max=4095, dBmin=0, dBmax=1599
  Unit: 16
    Control: name="IEC958 In Capture Switch", index=0
    Info: id=16, control=1, cmask=0x0, channels=1, type="INV_BOOLEAN"
    Volume: min=0, max=1, dBmin=0, dBmax=0