I am working on a video streaming device that uses the ADV7842 for HDMI and composite video input, and the ADAU1701 for analog audio input and audio mixing. The host processor only has a single TDM audio input port. THe ADAU1701 has no sample rate conversion ability, and the ADV7842 only provides MCLK output when it has a valid HDMI audio signal input. Currently, we are working around this by using an ICS581-02 auto-switching clock mux, which provides the ADAU1701 with either 12.288MHz MCLK from an oscillator or MCLK directly from the ADV7842 when available. This generally works (except for an occasional rare instance when the clock rate decoded from HDMI is much different than expected); however, the clock mux chip has gone obsolete and we have not found a suitable replacement.
Is there a recommended way to deal with switching between / mixing analog and HDMI audio inputs? Since the ADV7842 will decode either analog or HDMI, I imagine that there are other applications which use both digital and analog audio (note that we can accept HDMI video with either HDMI or analog audio, or a mix of both, or analog video with analog audio).
Currently we are looking at sample rate conversion parts, but I'm curious if there are other potential solutions.