vlc cannot play audio of DVD, but does play ripped .mp4/.mpg/.avi/.wmv/.mp3 files (sid)

[Zenaan Harkness]

I'm on sid, running VLC, using alsa audio.

I can play ("ripped") single files, audio and/ or video, just fine,
with vlc and mplayer, either ripped by me (from a DVD using handbrake)
or downloaded.

What I cannot do is insert a physical DVD, and then "Play disc" or
"Play directory" (either off the disc, or of the files just copied off
the disc). Well, I can play, but only the video plays, and vlc status
dialog shows me that various packets are played of the video track,
but 0 (zero) are played of the audio track.

Any ideas why audio off a physical DVD does not play?

TIA
Zenaan