Ok, so I misunderstood the idea of a period variable, many thanks for explanation Clemens.

I've just read that buffer_time also isn't what I think it was ;) It's a size of the ring buffer of sound card and it's length depends on hardware, am I right? So the best way is to depend on default values of hardware?

Anyway is there a method to play my wave for a specified short time? As I can see using timer interface is the only solution but still can't google anything useful :( Small example how to apply timers will be appreciated (I saw example timer.c from alsa-lib, but I'd prefer to read some explanation how the code works).

Thanks from advance for any replays.