David Esp Video Technical Blog

Sometimes Adobe Premiere may write to a source media file or proprietary folder-structure.  This may be considered a non-problem in most situations, but it is nevertheless worth being aware of.

This is nothing hidden, surreptitious or unheard-of, it’s explained in Adobe’s Help text and documentation.  However the potential consequences may not be obvious to a new user.  It may arise at various points of what we may regard as the greater process (workflow/manual) of ingesting media, consisting not only of Premiere’s Import of media but also subsequent manual updating of metadata or indeed automatic analysis such as speech recognition.  As of CS6 it can also occur as a result of adding Markers in Adobe Prelude.

Premiere likes to add and manage metadata for each media file.

• The good side of this is that it value-enhances these files, making them easier to locate, navigate and use, potentially increasing workflow productivity and asset usage.
• But there’s also a dark side – not necessarily Adobe’s fault (e.g. their approaches may well adhere to official media specifications) – but it may be that so-adulterated media files may cause difficulties to other applications (e.g. that may not fully take on board such standards).
  • In my experience, in the past, some (possibly poorly-written, but nevertheless useful) applications have refused to work with metadata-augmented files, again holding up productivity, in this case while the user figures out the issue and works out how to strip this data out, in order to progress.
  • Technically a non-problem, but potentially consequential to a workflow, backup software will (rightly, from its point of view) see the metadata-change as a file-change (e.g. as a consequent file-size change) and consider that the files have been updated.   Left to itself, the backup process (depending how it works/configured) will overwrite any previous copy of the files (e.g. the original files).   Even if the backup process prompts the user to confirm this, the naive user may be uncertain what to do,

Also, the user has the option at their discretion for Premiere to automatically store additional files (such as cache files and metadata sidecar files) alongside source media files.

• In the case of media represented as a straightforward single file (like a .jpg or .mpg file) this does not affect that media.
• However some media (e.g. TV-playable DVDs or XDCAM-EX video media) are stored as proprietary folder structures with defined contents, part of these contents being essence files (e.g. .vob files or .mp4 files) while other files alongside them etc. in that structure (e.g. DVD’s .IFO files or XDVCAM-EX’s .SMI files) contain metadata or index into them etc.  In this case, the consequence of adding further files into the structure will (in my experience) be acceptable to some applications and media players but not to others, which regard it as “pollution”, and may then reject such structures.  Certainly in the past I have seen this happen in some software applications and also even some (mostly old) TV DVD players.

This is a case for “situational awareness”: if one is aware of the nature and potential consequences of the adulteration (be it regarded as pollution or enhancement, depending on the workflow situation), one is then in a better position to be able to avoid or fix any asociated issues.

Detailed Questions etc.:

• I am not the only one to have slight misgivings, e.g. http://adobe.hosted.jivesoftware.com/message/4417177
• Does Adobe adulterate / pollute source media files?
  • It can, depending how it’s configured and the media file-type,  add its own metadata to the end of some files.  This data is in XMP format, an Adobe format (largely inspired from earlier Photoshop days) in XML.  For example a media file is mostly binary but (on Windows) if you put it in Notepad then the XML is readable as text at the end of the file.
    • In Premiere menu: [Edit > Preferences > Media] there are the XMP-related settings:
      • [Yes/No] Write XMP ID to files on Import
        • Help: <<Check this box to write ID information into XMP metadata fields.>>
      • [Yes/No] Enable Clip and XMP Metadata Linking
        • Help: <<Check this box to link clip metadata to XMP metadata, so that changing one changes the other.>>
  •  An alternative option is to have Premiere write metadata to sidecar-files:
    • http://help.adobe.com/en_US/premierepro/cs/using/WSE2397406-3FEB-43df-868D-68EB20BBC021.html
      • Adobe applications store metadata using the Extensible Metadata Platform (XMP). XMP is built on XML, which facilitates the exchange of metadata across a variety of applications and publishing workflows. Metadata in most other formats (such as Exif, GPS, and TIFF) automatically transfers to XMP so you can more easily view and manage it.
        • In most cases, XMP metadata is stored directly in source files. If a particular file format doesn’t support XMP, however, metadata is stored in a separate sidecar file.
        • Project assets without corresponding files don’t support XMP. Examples from Adobe Premiere Pro include Bars and Tone, Universal Counting Leader, Color Matte, Titles, Black Video, and Transparent Video.
      • Adobe Premiere Pro Separates metadata in these sections:
        • Clip Displays properties for clip instances you select in the Project panel or Timeline panel. This metadata is stored in project files, so it appears only in Adobe Premiere Pro.
        • File 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.
        • Link clip data to XMP metadata
        • In the Metadata panel, the Clip property value fields are internal. They reside in the Premiere Pro project file, and are readable by Premiere Pro alone. However, some of the property value fields in the Clip section have a link option box next to them. After you select the link option, Premiere Pro automatically enters the information that you enter into the Clip value field into a corresponding XMP field. {I assume this means a field in the media file itself or else its associated sidecar file}
    • http://helpx.adobe.com/media-encoder/using/export-settings-reference.html
      • Title: [Media Encoder Help / Export settings reference]
        • This is relevant to the greater (workflow, manual) process of ingesting of media, because some kinds of metadata generated by Premiere, such as speech analysis, are generated via the Adobe Media Encoder (AME).
      • Export and thin XMP metadata
      • You can choose what XMP metadata (if any) to include in the output file.
      • To open the Metadata Export dialog box, click the Metadata button in the lower-right corner of the Export Settings dialog box or choose Edit > Edit Metadata.
      • Note: You can perform many of the same actions in the Metadata category in the Preferences dialog box. (See Preferences.) Changes made in the Preferences dialog box don’t apply to selected items in the encoding queue, but the templates and rules are available for later assignment through the Metadata Export dialog box.
      • Specifying how and whether to include XMP metadata on output
        Use the Export Options menu to specify whether XMP metadata should be embedded in the output file, stored in a sidecar (.xmp) file, both, or neither.
      • If you choose None, then no XMP metadata from the source will be embedded in the file, and none of the other controls for XMP metadata export are available. Basic XMP metadata about the exported file—such as export settings and start timecode—is always exported, even when None is chosen.
      • Note: The Embed In Output File options are disabled for files of kinds for which XMP metadata can’t be embedded.
        Preserving XMP metadata from sources
        Many source assets contain XMP metadata. You can choose which XMP metadata from source assets should be preserved in the encoded output files by using a preservation rule.
  • Having imported a bunch of .jpg images to Adobe Premiere CS5.5, their file-size has reduced slightly.  Presumably this is a side-effect of Premiere’s Import process.
  • My immediate reaction: “How dare it affect my source images at all!”  I want to keep them as unaltered originals!  I had assumed (naively) that applications such as NLEs would essentially apply (by themselves) a read-only access to media files.
  • Consequently it would seem prudent to keep a separate copy of originals, inaccessible to Premiere.  I wonder if simply having them in a separate folder with all files’ properties set to read-only by the file system.  In my case, the file system is typically NTFS, but occasionally (in other projects and NLEs) I have in the past referenced media files on other file systems such as Mac’s HFS+ or from Network Attached Storage (NAS) etc.
  • Thinks: if Adobe needs or prefers to adulterate sources in this way, how does it cope when reading truly read-only files, as from say a CD or DVD?holding up the workflow.

This entry was posted on Saturday, November 10th, 2012 at 16:55 and is filed under Adobe, Formats, Prelude, Premiere, Sony EX XDCAM, video, XDCAM EX, XML. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.