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 tool tip 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. Beat markers from Soundbooth and the metadata generated by the Speech Search feature in Soundbooth and Premiere Pro are examples of temporal metadata.
Adobe Story also converts information from a screenplay (script) into XMP metadata that can automate the creation of shooting scripts, shot lists, and more.
To start the Adobe Story service from within After Effects, choose File > Go To Adobe Story.
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.
XMP metadata included in an F4V or FLV file can be read and used by ActionScript, so you can use XMP metadata to add interactivity to a video playing in Flash Player. One application of this feature is searching within an FLV file for temporal metadata, which can allow the user to begin playback at a specific word of dialog or at some other time associated with a specific temporal metadata element.
To selectively add and remove (thin) XMP metadata for a file, use export templates and the Metadata Export dialog box in Adobe Media Encoder.
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.
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.
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.
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), other native document formats for Adobe applications
MPEG formats (MP3, MPEG-2, MPEG-4)
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.
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.
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.
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 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.
When 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).
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 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, 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. (See Output modules and output module settings.)
When Include Source XMP Metadata is on, in some cases, rendering and exporting can take a long time because of the time that it takes to read and assemble XMP metadata from the source files. For this reason, the option is off by defa
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:
XMP metadata is written to sidecar (.xmp) files for some MPEG formats.
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.
After Effects writes startTimecode and altTimecode values into XMP metadata. You can view these values in the Start Timecode and Alternate Timecode fields in the Dynamic Media schema in the Metadata panel.
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 is not visible in the Metadata panel.
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.
For the most part, 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.
Adobe OnLocation and Encore provide one set of metadata properties for all assets. However, Adobe Premiere Pro, After Effects, and Soundbooth divide the Metadata panel into separate sections for different asset types.
To optimize the Metadata panel for your workflow, show or hide entire schemas or individual properties, displaying only those that you need.
If you use multiple workflows, each requiring different sets of displayed metadata, you can save sets and switch between them.
If you have a unique, customized workflow that the default metadata options don’t address, create your own schemas and properties.
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.
Instead of a Project panel, Soundbooth uses the Files panel.