Maybe a little OT but I'm hoping some expertise on this list can address this... quirk?
We were looking at the gain range of the mic input on a standard AC97 type of codec on a stock mobo, using winXP pro, and it looks like the MSB of the gain control register is never been used.
Register Definition btw : D16 : Mute D6 : Fixed 20dB Gain (Mic Boost)GN[4:0] 'Gain programmable from -34.5dB to 12dB in 1.5dB increments providing 32 levels.'
However our measurements are showing a 23-ish-dB range, not the listed 46.5dB, so the windows mixer value seems to ignore the available msb. Default value is 0x8008, so that would mean the default range of gain is between -10.5dB and 12dB. The msb is for values from -12dB down to -34.5.
I'm wondering if this is a bug or a feature :) Anyone have some input? (forgive the pun!)
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