Support the opus audio codec through opusenc gstreamer plugin in QAudioRecorder backend

I'm investigating why a SailfishOS audio recording application using QAudioRecorder doesn't support the opus codec.

It seems the only thing missing for support is that the gstreamer plugin of the QtMultimedia plugin doesn't know of the opusenc plugin of gstreamer.

From my naive point of view, it seems like the only thing needed would be something like

m_elementNames["audio/opus"] = "opusenc";

and some other code to support the options of the opusenc plugin.

As the code seems to probe for gstreamer plugin availability, this shouldn't be a problem if Qt runs against a gstreamer version which does not support opus.

Does this make sense? Do I miss something?