ESP32 A2DP Source - Callback Function

[mgepigon]

How exactly does the callback function for the data work (bt_app_a2d_data_cb)? Where does it get this 'data' from? I'm trying to manually put in an array myself (of a sinusoid) to be played to my Bluetooth speaker but it currently is just outputting noise with no semblance of the PCM sine wave I have the data array as.

I have seen other implementations of SD card audio or .wav file audio being played but not an array of PCM data written from scratch so encountered a bit of a wall here.