Clocks in Ardour are used to display time values precisely. In many cases, they are also one way to edit (change) time values, and in a few cases, the only way. All clocks share the same basic appearance and functionality, which is described below, but a few clocks serve particularly important roles.
In the transport bar of the editor window there are two clocks (unless you are on a very small screen), that display the current position of the playhead and additional information related to transport control and the timeline. These are called the transport clocks; the left one is the primary transport clock and the right one is the secondary transport clock. They look like this:
Editing the time in the transport clocks will reposition the playhead in the same way that various other editing operations will.
To show the current playhead position in a big, resizable window, activate Window > Big Clock. The big clock is very useful when you need to work away from the screen but still want to see the playhead position clearly (such as when working with a remote control device across a room). The big clock will change its visual appearance to indicate when active recording is taking place. Below on the left is a screenshot showing a fairly large big clock window filling a good part of the display, and on the right, the same clock during active recording.
On a few occasions Ardour needs to display time values to the user, but there is no obvious way to specify what units to use. The most common case is the big cursor that appears when dragging regions. For this and other similar cases, Ardour will display time using the same units as the secondary clock.
Having two transport clocks lets you see the playhead position in two different time units without having to change any settings. For example, you can see the playhead position in both timecode units and BBT time.
The transport bar also contains a set of 5 clocks that show the current selection range and punch ranges. Clicking on the punch range clocks will locate to either the beginning or end of the punch range. Similarly, clicking on the range clocks will locate to either the beginning or end of the current selection. In this screen shot there is no current selection range, so the selection clocks show an "off" state.
Every clock in Ardour has four different, selectable clock modes. Each mode displays time using different units. You can change the clock mode by Right-clicking on the clock and selecting the desired mode from the menu. Some clocks are entirely independent of any other clock's mode; others are linked so that changing one changes all clocks in that group. The different modes are:
In addition to the time-unit modes mentioned above, each of the two transport clocks (if you work on a small screen, you may only have one) can be independently set to display Delta to Edit Point in whatever time units its current mode indicates. This setting means that the clock shows the distance between the playhead and the current edit point, and it may show a positive or negative value depending on the temporal order of these two points. The clocks will use a different color when in this mode to avoid confusion.
To switch either (or both!) of the transport clocks into this mode, use Edit > Preferences > Transport and select the relevant checkboxes.
Note that when in Delta to Edit Point mode, the transport clocks cannot be edited.
New values for the clock can be typed in after clicking on the relevant clock. Clicking on the clock will show a thin vertical cursor bar just to the right of the next character to be overwritten. Enter time in the same order as the current clock mode—if the clock is in Timecode mode, you need to enter hours, minutes, seconds, frames. So, to change to a time of 12:15:20:15 you would type 1 2 1 5 2 0 1 5. Each number you type will appear in a different color, from right to left, overwriting the existing value. Mid-edit, after typing 3 2 2 2 the clock might look like this:
To finish the edit, press ↵ or Tab. To exit an edit without changing the clock press ESC. If you mis-type an entry so that the new value would be illegal (for example, resulting in more than 30 frames when Timecode is set to 30 frames per second), the clock will reset at the end of the edit, and move the cursor back to the start so that you can start over.
There is a shortcut available for those who wish to be able to edit the transport clocks entirely without the mouse. It can be found in Window > Key Bindings > Transport > Focus On Clock. If bound to a key (÷ on the numerical keypad is the default), then pressing that key is equivalent to clicking on the primary (left) transport clock, and editing can begin immediately.
One detail of the editing design that is not immediately obvious is that it is possible to enter part of a full time value. Suppose that the clock is in BBT mode, displaying 024|03|0029, and you want to alter the value to the first beat of the current bar. Click on the clock and type 0 1 0 0 0 0. Similarly, if it is in Minutes:Seconds mode, displaying 02:03:04.456, and you want to get to exactly 2 hours, click on the clock and type 0 0 0 0 0 0 0 to reset the minutes, seconds and milliseconds fields.
You can also type values into the clock that are intended as a relative change, rather than a new absolute value. Simply end the edit by pressing + or - (the ones on any keypad will also work). The plus key will add the entered value to the current value of the clock, minus will subtract it. For example, if the clock is in Samples mode and displays 2917839, you move it back 2000 samples by typing 2 0 0 0 and -, rather than ending with Enter or Tab.
Position the mouse pointer over the clock, and move the scroll wheel. Moving the scroll wheel up (⇑) increases the value shown on the clock, moving it down (⇑) decreases it. The step size is equal to the unit of the field you are hovering over (seconds, hours, etc.).
Position the mouse pointer over the clock, press the left mouse button and drag. Dragging upwards increases the value shown on the clock, dragging downwards decreases it, again with a step size equal to the unit of the field you began the drag on.