/*
 * call-seq:
 *   new [VideoPort|AudioPort|PostPort|Post...] -> object
 *
 * Create a new stream. The VideoPort and AudioPort used to create the stream are
 * extracted from the given parameters. It is possible to give an AudioPort or
 * a VideoPort directly, giving one or more PostPort's (which have to be input ports)
 * or giving post plugins directly whose input ports shall be used. The first suitable
 * ports are used. If there are no suitable audio or video ports among the parameters, 
 * these are created implicitely using autodetection.
 */
VALUE xs_new(int argc, VALUE *argv, VALUE class) {