The ALSA and pulse audio backends do not currently build. It requires a bit of work to make a audio only build using those backends work again.
Original report follows:
After changing the build parameter I use to build qtmultimedia, CMake finds conflicting options.
With -DFEATURE_pulseaudio:BOOL=ON and the alsa, gstreamer headers also installed:
[ 63s] CMake Error at /usr/lib64/cmake/Qt6/QtBuildInformation.cmake:375 (message):
[ 63s] Feature "pulseaudio": Forcing to "ON" breaks its condition:
[ 63s] WrapPulseAudio_FOUND AND NOT QT_FEATURE_gstreamer
[ 63s] Condition values dump:
[ 63s] WrapPulseAudio_FOUND = "TRUE"
[ 63s] QT_FEATURE_gstreamer = "ON"
[ 63s] Call Stack (most recent call first):
[ 63s] /usr/lib64/cmake/Qt6/QtFeature.cmake:277 (qt_configure_add_report_error)
[ 63s] /usr/lib64/cmake/Qt6/QtFeature.cmake:399 (qt_feature_check_and_save_internal_value)
[ 63s] /usr/lib64/cmake/Qt6/QtFeature.cmake:597 (qt_evaluate_feature)
[ 63s] /usr/lib64/cmake/Qt6/QtModuleHelpers.cmake:516 (qt_feature_module_end)
[ 63s] src/multimedia/CMakeLists.txt:14 (qt_internal_add_module)
The build system first detected the gstreamer installation, then found a conflicting build option enabled.
This raises another issue: There may be a reason to have alsa and pulseaudio conflicting but why should they conflict with gstreamer?