Overriding sub-comp format
Sub-compositions have been described as layers that reference a composition as a source. Therefore, if two layers refer to the same composition, any changes made in this comp will affect both of them.
The section dedicated to comp caching explains that, by default, Autograph does not reuse the final rendering of a composition, in this case, of multiple references. However, the results of calculations on the layers' internal parameters are reused as much as possible if they are identical between two sub-comps.
So why not reuse this end result? Simply because Autograph allows you to locally modify a reference to create a variation of this composition. The same applies when you modify the transformation parameters of a sub-comp without any loss in quality, as explained in the section dedicated to Rasterization.
Overriding sub-comp format to create variations based on one unique composition
Let's take a look at the following example:
We create two compositions in the project panel:
- “Comp1”, with a 640×480 format (Preset: "PC VIDEO")
- “Comp2”, with a 1920×1080 format (Preset: "HD")
- We add a Constant generator, creating a new layer.
- We define its Output Format to "Composition Format", and size this Constant to 640×480 pixels (similar to “Comp1” format)
- We drag and drop “Comp1” as a new layer twice, to use it as a sub-comps
- We click the triangle in the main line to unfold parameters
- Then unfold Source > “Comp1”
All parameter generator slots contain a purple Share icon. We single-click on “Comp1” in the Project panel to select it and inspect it's parameters in the Properties panel.
All parameters also contain this Share icon. That means that the original “Comp2” and its reference as a sub-comp share the same parameters and therefore the same values or states. Any change made to a parameter in the Properties panel will also appear in the Timeline, since all these parameters are shared.
Keep this subtle difference in mind. The parameters of the original composition, visible here in the Properties panel, and those of the layer that refers to it, here in the Timeline, are NOT the same, but they share the same values or states.
It is therefore possible to locally unshare any parameter, in order to give it another value or state.
Let's unshare the Format parameter, by clicking on the Share icon and choosing Unshare in the top left part of this menu.
The Share icon is gone, and now you can locally change this parameter without affecting the Format param of the original “Comp2”.
When you want to override the format, keep these two important things in mind:
- If you don't unshare this param before modifying it, the original composition, as well as all other sub-comp referring to it, will be modified too
- After unsharing the format, if you decide to switch to Custom mode, Autograph will also display the Size parameter, which will also be shared by default
When a composition uses a preset for its format, the Size parameter is not displayed, but it does exist. Before changing it, you MUST also unshare it, otherwise this parameter, even hidden in the original composition, will be changed as well. This has no real implications if the original composition keeps using a preset as its format, but if you switch the original composition to Custom mode while it is used as a sub-comp in several places in your project, this could be problematic.
For more information about sharing parameters, please refer to the dedicated section.
Who can also override a composition
Two other panels can override composition format:
- The Viewer: to preview the behavior of the layers according to a format change; in particular for those calculating their position according to it.
- The Render Manager: in order to render several variants of the same composition, specifically designed to be responsive. You can thus produce, with a single main composition, 4:3, 16:9, square, and 9:16 versions of the same project.