VLC does not display audio waveforms whatever the properties of the stream or the file you are writing.
If you want the waveform displayed, then you could just Play the network stream in VLC (without converting the stream to a file), then have Audacity record the stream. See Recording Computer Playback on Linux. When the stream is finished playing, export the Audacity recording to your chosen format.
Of course you could play the stream in VLC while transcoding it to a file and also record the playback in Audacity, but you will risk dropouts in the stream or the waveform if you ask too much of your computer.
Gale