No way to control volume/level of a QAudioInput

The Multimedia API provides no way to control the volume/level of an audio device. For output, this is inconvenient but tolerable since the audio stream can be scaled in software. For audio input, however, the volume really needs to be controlled at the hardware level in order to limit noise and prevent clipping.

At present, the only way to do this is to use OS-specific control interfaces, which defeats the purpose of having an OS-independent audio API in Qt.