Audio mixing uses two audio streams with the same audio sample rates. The audio mixer block does not perform any upsampling or downsampling. This Figure shows the block diagram of the audio mixer block.
The mixing is implemented using additive logic on 24-bit audio samples as shown in This Figure. Each audio stream is multiplied with a corresponding 16-bit volume control and then added.
X-Ref Target - Figure 33-15
The mixed audio in AXI-S format is forwarded to the DisplayPort source controller and the PL. A small holding buffer that supports AXI-S is used to handshake with the PL. The audio channel does not accept any back pressure from the PL interface.