XMP metadata

Metadata is—in the simplest sense—data about data. In practical terms, metadata is a set of standardized information about a file, such as author name, resolution, color space, copyright, and keywords applied to the file. For example, most cameras attach some basic information to video files, such as date, duration, and file type. Other metadata can be entered as shot-list information in OnLocation or at the capture stage in Adobe Premiere Pro. You can add additional metadata with properties such as location, author name, and copyright. Because you can share, view, and use this metadata across Adobe Creative Suite applications, you can use this information to streamline your workflow and organize your files.

The Extensible Metadata Platform (XMP) is the metadata standard used by Adobe applications. Metadata that is stored in other formats—such as Exif, IPTC (IIM), GPS, and TIFF—is synchronized and described with XMP so that it can be more easily viewed and managed. For example, adjustments made to images with Adobe Camera Raw are stored as XMP metadata. The XMP standard is based on XML.

A metadata schema is a collection of properties specific to a given workflow. The Dynamic Media schema, for example, includes properties such as Scene and Shot Location that are tailored for digital video projects. Exif schemas, by contrast, include properties tailored to digital photography, such as Exposure Time and Aperture Value. More general properties, such as Date and Title, appear in the Dublin Core schema. To see a tooltip with information about a specific schema or property, place the pointer over it in the Metadata panel. You can create your own schemas using commands in the Metadata panel, and you can import schemas and share them with others as XML files.

Metadata is divided into two general categories: static metadata and temporal metadata. Static metadata is metadata that applies to an entire asset. For example, the copyright and author information for a video clip apply to the entire clip. Temporal metadata is metadata that is associated with a specific time within a dynamic media asset. 

You can view static XMP metadata for a file in Adobe Bridge.

After Effects scripts and expressions can read and use data stored in markers. Because XMP metadata for source footage items can be converted to layer markers, expressions, and scripts can work with XMP metadata. Scripts can also operate on the XMP metadata for a file outside of the After Effects context, both for the automation of common tasks and for creative uses.

Embedding XMP metadata versus including XMP metadata in sidecar files

In most cases, XMP metadata for a file is stored in the file itself. If it isn’t possible to write the information directly into the file, XMP metadata is stored in a separate file called a sidecar file, with the filename extension .xmp. For information on which file formats After Effects can write XMP metadata directly into, see XMP metadata in After Effects.

In most cases, XMP metadata remains with the file even when the file is converted to a different format—for example, from PSD to JPG. XMP metadata is also retained when files are placed in a document or project in an Adobe Creative Suite application.

Online resources about XMP metadata

Go to the XMP Developer Center section of the Adobe website for the XMP specification, information on integrating XMP metadata with your software and workflow, the XMP SDK (software development kit), and forums about XMP metadata.

XMP metadata in After Effects

For 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 Effects

After Effects can import XMP metadata from many formats, including the following:

• Camera formats: AVCHD, HDV, P2, XDCAM, XDCAM EX

• Image formats: GIF, JPEG, PNG, PostScript, TIFF

• Common multimedia container formats: FLV, F4V, QuickTime (MOV), Video for Windows (AVI), Windows Media (ASF, WAV)

• Authoring formats: InDesign documents, Photoshop documents (PSD), and other native document formats for Adobe applications

• MPEG formats (MP3, MPEG-2, MPEG-4)

• SWF

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 the uniqueness of values.

XMP ID values are written to source files when 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 generally already have an XMP ID.

The Write XMP IDs To Files On Import preference is enabled by default.

Working with XMP metadata in After Effects

The Metadata panel

In 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 the 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 or Files Metadata Display from the Metadata panel menu.

Conversion of XMP metadata to layer markers

When you create a layer based on a footage item that contains XMP metadata, the temporal metadata can be converted to layer markers.

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. 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. Changes made to the layer markers based on the source file's XMP metadata don't affect the XMP metadata in the source file.

For information on using expressions together with the contents of layer markers, see MarkerKey attributes (expression reference).

Exporting XMP metadata from After Effects

When 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 and Project panels, 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, select Include Source XMP Metadata in the output module settings for the output file. If Include Source XMP Metadata is deselected, the only XMP metadata that is written to the output file is a unique ID. 

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:

• QuickTime (.mov)

• Video for Windows (.avi)

• Windows Media (.wmv)

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 Effects

When 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 isn't visible in the Metadata panel.

About file, clip, and project XMP metadata

Generally, Adobe video and audio applications deal with XMP metadata very similarly. Some small distinctions exist, however, reflecting the unique workflow stage that each application addresses. When using applications in tandem, an understanding of these slightly different approaches can help you get the most out of metadata.

Separates metadata in these sections:

Displays properties for clip instances you select in the Project or Timeline panels. This metadata is stored in project files, so it appears only in Adobe Premiere Pro.

Displays properties for source files you select in the Project panel. This metadata is stored directly in the source files, so it appears in other applications, including Adobe Bridge.

Separates metadata in these sections:

Displays properties for the overall project. If you select Include Source XMP Metadata in the Output Module Settings dialog box, this information is embedded into files you output from the Render Queue.

Displays properties for source files you select in the Project panel. (If you select a proxy, properties for the actual file appear.)

For After Effects, both Project and File properties are stored directly in files, so you can access this metadata in Adobe Bridge.

Show or hide XMP metadata

To optimize the Metadata panel for your workflow, show or hide entire schemas or individual properties, displaying only those that you need.

Save, switch, or delete metadata sets

If you use multiple workflows, each requiring different sets of displayed metadata, you can save sets and switch between them.

Create schemas and properties

If you have a unique, customized workflow that the default metadata options don’t address, create your own schemas and properties.

Edit XMP metadata

In Adobe video applications, similarly named properties are linked in the Metadata and Project panels. However, the Metadata panel provides more extensive properties and lets you edit them for multiple files simultaneously.