Hello, Let's go trhough your improvements one by one and integrate them. I got around reading most of them. As I remarked in a previous mail, there is not really a need to have a separate sync button. You could simply use the current cue ::cue in which case it is also possible to mark the current cue directly. This means that I would propose the following changes - your clock-drivewr bases itself on the last retrieved cue not on the Z cue. This is also good for songs which have a sudden displacment in beat positionings - the abstract clock-driver class gets its function request_sync renamed to mark_beat. - the mark_beat function is called from within the cue_set function in player-core.c++. The Player::sync function is removed This part of the code can then also already be taken out of the compile_jack defines.