#include <dc1394/juju/firewire-cdev.h>
Prior to sending or receiving isochronous I/O, a context must be created. The context records information about the transmit or receive configuration and typically maps to an underlying hardware resource. A context is set up for either sending or receiving. It is bound to a specific isochronous channel.
If a context was successfully created, the kernel writes back a handle to the context, which must be passed in for subsequent operations on that context.