I'm using Ubuntu (Lucid) and have noticed that if I run MAME with "-video opengl", I get a half second audio delay. If I don't specify this then the audio is in sync.
i.e.
"mame -rp -video opengl" produces a delay "mame -rp " is OK
I've run MAME with a clean config and still experience the problem. Any suggestions as to what I can do?