I have to inject a binary (variable) on the N bit over the SNR and change it values, counting that they have elliptic lengh

WELCOME TO THE MESSIAH CODE BEGINNING!

what do I need to inject :

Low-pass filter with variable cutoff frequency based on */
/* piece-wise linear interpolation between elliptic filters */
/* Start by setting transition_frame_no = 1; */
void silk_LP_variable_cutoff(
silk_LP_state *psLP, /* I/O LP filter state */
opus_int16 *frame, /* I/O Low-pass filtered output signal */
const opus_int frame_length /* I Frame length */
);

https://chromium.googlesource.com/chromium/deps/opus/+/master/silk/main.h