Qt configure warning No backend for low level audio found

I am setting up a cross-compile environment for Raspberry Pi (compiling on AlmaLinux 9). When I run the Qt configure program on AlmaLinux it succeeds but I get error:

WARNING: No backend for low level audio found.

What does this warning mean? What is missing, and is the problem on the Raspberry or the AlmaLinux computer? How do I fix this?

You can use the following command to search a directory files for a string:

grep -r "No backend for low level audio found." ../qt-everywhere-src-6.5.1/

and the response will be:

../qt-everywhere-src-6.5.1/qtmultimedia/src/multimedia/configure.cmake:    MESSAGE "No backend for low level audio found."

if you look inside qt-everywhere-src-6.5.1/qtmultimedia/src/multimedia/configure.cmake

you see:

qt_configure_add_report_entry(
    TYPE WARNING
    MESSAGE "No backend for low level audio found."
    CONDITION NOT QT_FEATURE_alsa AND NOT QT_FEATURE_pulseaudio AND NOT QT_FEATURE_mmrenderer AND NOT QT_FEATURE_coreaudio AND NOT QT_FEATURE_wmsdk AND NOT ANDROID AND NOT WASM
)

which means none of the mentioned libraries were found on your system.

running sudo apt-get build-dep qt6-multimedia-dev should reveal the dependancies, anything other than qt related libraries.