Stop frames pause the composition Playout temporarily without pausing the elements within the composition (tickers, clocks, still image sequence) and can be used to dynamically extend the duration of a composition. Stop frames are interpreted differently in just:play and just:live. In just:play, the “Hold” duration of a Stop frame is proportional to the length of the duration, which is set in the Inspector of just:play. In just:live, a trigger has to be received by the composition to continue. Otherwise, it will be held infinitely (which may be useful for a corner logo graphic, for example). Stop frames can also be added/removed/modified in the “Document” tab of the Inspector in Composition Builder.
There are two main use cases for Stop frames:
Every composition which is used as “Infinite graphics” must contain ONE stop frame; otherwise the graphics will go off the air once the composition reaches its predefined composition end.
Infinite Graphic Layer (“Always on” Cornerlogo)
Imagine you have a corner logo that is used on an infinite graphic FX Layer. Now, the purpose of the Infinite GraphicLayer is that a graphic will be displayed infinitely. But compositions created with Composition Builder have a defined duration. As you cannot create a composition with an “infinite” duration, you add a Stop frame to the composition instead, which “stops” the timeline of the composition. This makes sure that the corner logo can be used on an Infinite Graphic layer for an infinite time.
Dynamic Duration in just:play
Imagine you have a lower third composition with an in-animation, a main part, and an out-animation. Now you want to show this lower third over videos with varying durations, and the display duration of the lower third should match each video accordingly. In this situation, you can add one or several Stop frames to your composition, thus allowing it to have a dynamic duration without losing the original duration of any in- or out-animation.
In the figure above, you can see a composition created with Composition Builder on an FX Layer of just:play. This composition has a stop frame and the duration has not yet been changed.
In the figure above you can see the same composition as above, but in this case, the duration has already been changed (by dragging the end of the composition or by using the Inspector of just:play). In the top area of the composition, there is a grey area, which is annotated with “Hold Duration”. By changing the duration of a composition, you also change the “Hold” duration.
Dynamic Duration in just:live
In just:live the behaviour is a little different. A Stop frame is held infinitely and must be released by the user, who can issue a trigger. A held Stop frame is indicated by a RED triangle, and the thumbnail of the FX Layer changes accordingly.