for spec 4121...I/F format: MSB justified, LSB justified (24/20/16bit) and I2S, so if we have 32, it can not lock..
It looks like your source devices are running the bit clock at the frequency needed for 32-bit words. If a 16-bit file is played with that clocking, then the 16-bit music resides in the most signification 16-bits of the 32-bit data words. The less significant 16-bits of the 32-bit data words will all be set to zero. How AK4121 handles that I don't know. It could be the bit clock frequency will be too high for AK4121, given whatever the LRCK framerate frequency is.
