File Bundles


This document describes OpenTimelineIO’s file bundle formats, otiod and otioz. The intent is that they make it easier to package and send or archive OpenTimelineIO data and associated media.

Source Timeline

For creating otio bundles, an OTIO file is used as input, whose media references are composed only of ExternalReference that have a target_url field pointing at a media file with a unique basename, because file bundles have a flat namespace for media. For example, if there are media references that point at:




Because the basename of both files is, this will be an error. The adapters have different policies for how to handle media references. See below for more information.

URL Format

The file bundle adapters expect the target_url field of the media_reference to be in one of two forms (as produced by python’s urlparse library):

  • absolute path: “file:///path/to/some/file” (encodes “/path/to/some/file”)

  • relative path: “path/to/some/file” (assumes the path is relative to the current working directory when invoking the adapter).


File bundles, regardless of how they’re encoded, have a consistent structure:

  • something.otioz (or .otiod)

    • content.otio

    • version.txt

    • media

      • media1

      • media2

      • media3

content.otio file

This is a normal OpenTimelineIO whose media references are either ExternalReferences with relative target_urls pointing into the media directory or MissingReference.

version.txt file

This file encodes the otioz version of the file, in the form 1.0.0.

Media Directory

The media directory contains all the media files in a flat structure. They must have unique basenames, but can be encoded in whichever codec/container the user wishes (otio is unable to decode or encode the media files).

Read Behavior

When a bundle is read from disk, the content.otio file is extracted from the bundle and returned. For example, to view the timeline (not the media) of an otioz file in otioview, you can run:

otioview sommething.otioz

This will only read the content.otio from the bundle, so is usually a fast operation to run.


When building a file bundle using the OTIOZ/OTIOD adapters, you can set the ‘media reference policy’, which is described by an enum in the file_bundle_utils module. The policies can be:

  • (default) ErrorIfNotFile: will raise an exception if a media reference is found that is of type ExternalReference but that does not point at a target_url.

  • MissingIfNotFile: will replace any media references that meet the above condition with a MissingReference, preserving the original media reference in the metadata of the new MissingReference.

  • AllMissing: will replace all media references with MissingReference, preserving the original media reference in metadata on the new object.

When running in AllMissing mode, no media will be put into the bundle.


The OTIOD adapter will build a bundle in a directory stucture on disk. The adapter will gather up all the files it can and copy them to the destination directory, and then build the .otio file with local relative path references into that directory.


The OTIOZ adapter will build a bundle into a zipfile (using the zipfile library). The adapter will write media into the zip file uncompressed and the content.otio with compression.

Optional Arguments:

  • Read:

    • extract_to_directory: if a value other than None is passed in, will extract the contents of the bundle into the directory at the path passed into the extract_to_directory argument.

Example usage in otioconvert

Convert an otio into a zip bundle

otioconvert -i somefile.otio -o /var/tmp/somefile.otioz

Extract the contents of the bundle and convert to an rv playlist

otioconvert -i /var/tmp/somefile.otioz -a extract_to_directory=/var/tmp/somefile -o /var/tmp/somefile/somefile.rv