[LAD] jack plugin

Hi Developers. I have more as one sound players on my system mplayer, vlc, qmmp ... Each of em uses jack output , for example 2 independent instances of mplayer mplayer -ao jack  -srate 16000 '/home/alf/mp3/mettwoch-de-doof-nuss.mpa.mp2' mplayer -ao jack  -srate 16000 '/home/alf/mp3/effeckt006.mp3' So far everything is excellent. How i do write my own DSP plugin for jack ? I wanna use my DSP plugin at this point, where all input channels are mixed together . How my plugin can ioctl() detect current samplerate, endianess, nr channels, samples interleaved or not, ... and maybe some more stream parameters. How do compile jack plugins ? What #include-s  must be used ? If my plugin will grow, and eat more and more CPU, how i prevent x-runs ? Is somewhere _simple_ C example how i can write jack plugins ? In simplest case - what is minimal program where i do each sample divide by 2 ( or for 16bit short type just  shift  sample>>1 ) Tnx in advance. Alf ----