HDMI sink signals it's supported formats to the HDMI source using the DDC/EDID, using SAD (short audio descriptors).
Can somebody fill in my gap in knowledge, how the HDMI sink then determines in what format is the audio data received?
(That will also probably be the partial answer for the OP how to grasp the problem)
Usually, HDMI receiver codec just provides a multichannel raw audio data (4x I2S or TDM), that then gets interpreted by the decoder. Question is, how the decoder decides, whether it is receiving raw LPCM, or compressed garbage?
Thx, Y.