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HinTak / seeed-voicecard

This is an enhancement fork with the explicit aim of supporting current shipping Raspbian/Ubuntu kernels without requiring downgrading. Please donate at https://hintak.github.io/ if it works for you. Use vX.Y branch for kernel version vX.Y
GNU General Public License v3.0
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4-Mic Array "only" 12 bit ~65dB dynamic !? AC108 delivers 24 bit, why does the driver throw 12 bit away? #13

Open v1tat opened 1 year ago

v1tat commented 1 year ago

I got the 4-Mic Array on a Pi Zero 2 running, with your latest 6.1 branch. I used the modifications of: JaPhoton posted here: https://github.com/respeaker/seeed-voicecard/issues/309 that fixed the problem, that restarting ends up sometimes of mixed channel order. But now i record, in audacity, or arecord (S32_LE) but it ends up that only 12 bit are provided !? (audacity smallest nonzero value is 0.0004) I checked with the Osci and see that the AC108 delivers 4 Channel 24 bit, so it looks as the driver ac108.c ?? throws the lower 12 bit away ???

codepainters commented 1 year ago

Note, that Pi can pack only 32 bits per I2S (stereo) channel, and 2 TDM slots are inserted into single 32-bit channel slot.