HDMI Video to RCA Audio
The signal on RCA Video output is called &quot;composite video&quot;.
You can find &quot;HDMI to composite video converters&quot; online, with an HDMI input and a RCA output with composite video. If the product specification says &quot;composite video output&quot; it'll be the same signal that was on oldskool RCA video outputs, so that should work for your project.