- +

OK, CONFUSE THEM !

• sometimes, positional sync has to be used as for speed sync:
  • e.g. using SMPTE/MTC to sync different devices/apps
• handling this is quite tricky
• basic model:

               last_position = 0;
  	     interval = 250000; // microseconds
  
               while (1) {
                  current_position = get_transport_position();
                  set_current_speed (current_position - last_position/interval);
                  usleep (interval);
               }

• tracks the current speed, but current speed may change significantly every time we compute it
• sounds terrible and doesn't actually keep up with current position
• add hysteresis:

       set_current_speed ((get_current_speed() * X) + 
  	                    (current_position - last_position/interval) * Y);

• that dampens the changes (if X and Y are chosen carefully).
• still need code to compare current transport position with our own, and adjust speed to compensate (or jump if non-linear motion has occured).