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XMP metadata in After EffectsFor an introduction to XMP metadata, see About XMP metadata. When After Effects imports a file with associated XMP metadata, you can view the static metadata in the Metadata panel, convert the temporal metadata to layer markers, use the metadata to facilitate your work within After Effects, and include the metadata in output files. The After Effects scripting interface provides additional tools for using and interacting with XMP metadata. Importing files with XMP metadata into After EffectsAfter Effects can import XMP metadata from many formats, including the following:
When you import a file that contains XMP metadata, After Effects shows a “Reading XMP metadata from footage” status message while it reads the metadata from the source file. One especially useful piece of metadata about each asset is its unique ID number, a value that distinguishes the asset from all others at all stages of the workflow. The unique ID value enables the application to recognize a file as being the same file as one encountered before, even if the filename has changed. One advantage of these unique ID values is that each application can use this information to manage cached previews and conformed audio files, preventing additional rendering and conforming. The ID values used by XMP are Globally Unique Identifiers (GUIDs), 16-byte random numbers that are commonly used to ensure uniqueness of values. XMP ID values are written to source files when they are imported into After Effects if the Write XMP IDs To Files On Import preference is selected in the Media & Cache preferences category. This preference setting affects other Adobe applications, too; see the helpful text in the Preferences dialog box for details. If a file already has an XMP ID, then After Effects doesn’t write a new one, and no change is made. Files created by recent versions of Adobe applications will, in general, already have an XMP ID. The Write XMP IDs To Files On Import preference is on by default. Important: The Write XMP IDs To Files On Import preference
only controls whether unique ID values are automatically written
to files when they are imported. This preference does not control
whether XMP metadata is written to a file under other circumstances,
such as when you edit metadata in the Metadata panel.
Note: Because writing the ID to a file is considered a modification,
the modification date of a source file may be updated the first
time the file is imported.
Working with XMP metadata in After EffectsThe Metadata panelIn After Effects, the Metadata panel (Window > Metadata) shows static metadata only. Project metadata is shown at the top of the panel, and Files metadata is shown at the bottom. Temporal metadata is visible in After Effects only as layer markers. Project metadata is shown in the Metadata panel as soon as you open the panel. You can add and change information in any of the metadata categories. This information shows up in Bridge when the project file is selected and is also embedded in files rendered and exported using the render queue when the Include Source XMP Metadata output module option is selected. To see Files metadata in the Metadata panel, you must first select a file in the Project panel. You can then add or change information in any of the metadata categories. If you select multiple files, then changes that you make will be made in all of the selected files. Any changes made to source file metadata are immediately written to the source files. To change which metadata categories and fields are shown in the Metadata panel, choose Project Metadata Display Preferences or Files Metadata Display Preferences from the Metadata panel menu. Conversion of XMP metadata to layer markersWhen you create a layer based on a footage item that contains XMP metadata, the temporal metadata can be converted to layer markers.
During this conversion, After Effects shows a “Reading XMP markers from footage” status message. These layer markers are fully editable, just as any other layer markers. (See Layer markers and composition markers.) Changes made to the layer markers based on the source file’s XMP metadata do not affect the XMP metadata in the source file.  To restore
the layer markers for a layer to those read from the layer’s source’s
XMP metadata, right-click (Windows) or Control-click (Mac OS) any
marker on the layer and choose Update Markers From Source. This
command also removes any markers that you have added to the layer.
You can use this command to manually create layer markers from XMP
metadata if you did not have the Create Layer Markers From Footage
XMP Metadata preference selected when you created the layer.For information on using expressions together with the contents of layer markers, see MarkerKey attributes (expression reference). Exporting XMP metadata from After EffectsWhen you render and export a composition, you can write XMP metadata to the output file that includes all of the XMP metadata from the sources for that composition. This includes all of the composition markers and layer markers in the composition, all of the XMP metadata from the source files on which the layers in the composition are based, comments from the Comments columns in the Timeline panel and Project panel, and the project-level XMP metadata for the project in which the composition is contained. XMP metadata from nested compositions is recursively processed and included in the output. To write all of the XMP metadata to the output file, make sure that the Include Source XMP Metadata option is selected in the output module settings for the output file. If the Include Source XMP Metadata option is deselected, the only XMP metadata that is written to the output file is a unique ID. (See Output modules and output module settings.) In addition to storing XMP metadata in After Effects project (.aep, .aepx) files and source documents used by Adobe applications (for example, .psd), After Effects can write XMP metadata directly into the files for many container formats, including the following:
For files of other types, the Include Source XMP Metadata option is unavailable. When you render and export a file and include the source XMP metadata in the output file, XMP metadata is written to an output file before the first frame of the composition is rendered. If the Render Details section of the Render Queue panel is open, After Effects shows a “Gathering XMP Metadata from Sources” status message while it compiles the metadata from the sources used in the composition being rendered. XMP metadata that is written to a file is inserted in an XML data structure separate from the audio and video data itself. You can view this plain-text XML data just as you view any other plain-text data, and you can use and manipulate it with scripts of various kinds. Re-importing XMP metadata into After EffectsWhen you import a file into After Effects that has been rendered and exported from After Effects using the Include Source XMP Metadata option, all of the XMP metadata that was written to the output file is available as layer markers when the file is used as the source for a layer in a composition. This XMP metadata is not visible in the Metadata panel. Note: When you import a file that contains XMP metadata and use
that file as the source for a layer, After Effects filters redundant
XMP metadata. This prevents an accumulation of duplicate markers
when you use a file in After Effects that was rendered and exported
out of the same project—for example, when pre-rendering a piece
of a project.
Video tutorials about markers and XMP metadataTo view video tutorials on working with markers and XMP metadata go to the Adobe website: 
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To enable the automatic conversion of XMP metadata to layer
markers, select the Create Layer Markers From Footage XMP Metadata
preference in the Media & Disk Cache preferences category.