I have connected a MAX98357A I2S amplifier and a TDK/Invensense ICS-43434 microphone to a Hikey960. I can succesfully play back 16-bit stereo 48kHz samples and record in the same format. However, the recording volume is very low. I suspect the cause is the ICS-43434 being a 24-bit microphone and therefore I may be losing 8-bits of significance. Is there a way of setting the PCM bitrate on the Hikey PCM audio driver?
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Hmm got to capture at 24 bit but then it wouldn play it back on the device. Also tried 32 bit but that wouldn capture. Also, when playing back the 24-bit capture on a desktop machine, the volume wasn significantly higher, and the sample was played back 1.5 or twice as fast. So not too sure what I did there (changed some values in hisi-i2s* driver files).
perhaps I’m just looking for a microphone gain setting…