I have added DC blocking cells to all of my serial audio ports inside Sigma studio project to be able to detect -96 dBFS and play audio based on the marketing requirement.
The DSP input level detector detects this low level signal and passes it to two switches (main & priority). My DSP signal flow has fail over mechanism such as if the priority signal passes this low threshold the priority audio will play. I also have the fall back flow which if all the audio signal goes away analog 1 will play if it is connected ( mostly test features for installer)
at this time , I don't know how to figure out the value for the DC input entry to switch to the priority.
Attached is my DSP signal flow. DSP is receiving 4 different audio sources (I2S format) and based on the main and priority switches it will play that selected source.
The current threshold is set for -64 dBFS.