I can confirm the gstreamer patch is not needed in xenial as described by Alfonso, however qtmultimedia patch is needed as the opus encoder is installed but it is not recognized by QGstreamerAudioEncode (it is not mapped).
I can confirm the gstreamer patch is not needed in xenial as described by Alfonso, however qtmultimedia patch is needed as the opus encoder is installed but it is not recognized by QGstreamerAudio Encode (it is not mapped).