What does "CHLEN" and "DATLEN" actually mean in the context of I2S

[CLeo.1]

Hi guys I am having troubles in understanding the "CHLEN" & "DATLEN" from PG. 2251 from the

STM32H753ZI

The reason I am asking because I am doing DSP, and I noticed when I change DATLEN from 16BIT -> 24BIT my DSP works perfectly, but when its on the 16BIT setting the wave looks messed up.

I also know it has to do with some sort of DMA as testing changing around MSIZE & PSIZE the wave form changes

I tried also probing it DATLEN doesnt do anything but I noticed CHLEN changes the SCLK

If anyone can explain to me this would be amazing

[Piranha]

CHLEN is the number of time slots for bits and determines the frame length. DATLEN is a number of actual data bits, which will be inserted in these time slots. RM0433 figure 624 explains it very clearly.