I wrote an Alsa driver with copy callbacks and it worked. Later read that you can use copy callbacks if you want to use dmix so I rewrote it to not use copy callbacks. I don't see much documentation on dmix (/etc/asound.conf). When I put dmix in there, I can run two versions but the framework never updates the application pointer so I get no data. I take the dmix out and it works fine. No clue on what to do. Bruce