andysworkshop / usb-microphone Goto Github PK

Thanks for your project which gave me a lot of help,but there is one point I dont understand;

int16_t sample = (data_in[0] & 0xfffffffe) | (rand() & 1);

How can this" take the most significant 16 bits and respect the sign bit" ?
I think this can only take the lower 16 bits without sign bit.
thanks

hi , can i use 2 microphones NMP441 microphone i2s ?

I got some pop noise when enable graphicEqualiser.
I attach a wav file recored by audacity.
pop_noise.zip
If I disable the graphicEqualiser, everything is fine, although the background noise may raise a little bit.
The hardware is almost the same as yours except the MCU is STM32F446RE.
Could you give me some suggestion to investigate the reason ?
BTW, In the code :
https://github.com/andysworkshop/usb-microphone/blob/master/Core/Inc/Audio.h#L230
what the purpose of make the LSB with a random bit ?
Thanks in advance.