UCLS/UCS specifications and tools
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This package contains the UCLS/UCS specifications, associated tools, sample UCLS/UCS, and unit tests to help you get started in generating or consuming UCLS content libraries.


To use this package, clone this repository.


The python scripts in this package require the packages enumerated in requirements.txt. To install those packages, run the following:

$ pip install -r requirements.txt

Getting Started

The tools folder contains Python scripts for validating a UCLS library. I.e. given a root folder containing media files and UCLS xml files describing those media files, the validator.py will validate that those xml files are valid UCLS xml files and that the media files they describe exist where they should be. The samples folder contains various examples of such (albeit simple) UCLS libraries. Both can be seen in action by running the following:

$ cd <package folder>\tools\validator
$ python validator.py -l "..\..\..\samples\video-only\library.xml" -t unc -o "output.log"

You should see the following output:

Performing validation...
<Path to package folder>\samples\video_only
Everything looks good!

The script also supports validating a library in AWS S3. The command line for that would look similar to the following:

$ Python validator.py -l <s3 key path to library xml file> -b <bucket> -a <your access key> -s <your secret key> -t s3 -o "output.log"

Additionally, you can also use generate_ucls.py to generate UCLS/UCS xml files for a library of media files. All you have to do is give the full path to the root folder containing media files to crawl for. The command line would look something like the below:

$ cd <package folder>\tools\validator
$ python generate_ucls.py -r <local drive folder> -l ucls_gen.log

It'll generate xml files in the folder you passed in with -r. To verify the generated xml files, you could then do the following:

$ cd <package folder>\tools\validator
$ python validator.py -l <local drive folder>\library.xml -t unc -o "output.log"

Note that generate_ucls.py requires an ffprobe executable to have been installed and be in your path. See https://www.ffmpeg.org for how to get it installed. The ffprobe python package in theory could've been used in lieu of this, but as of this writing, it was found to be slow and sometimes would hang on certain files, so it's not recommended at this time.


The schemas folder contain XSD files that constitute the UCLS and UCS specifications. They are described below.


This XSD defines the schema for a UCLS Library. In addition to defining the schema for a top level xml from which a library definition begins (i.e. where parsing starts), it also defines basic types used in the other XSD files.


This XSD defines the schema for a UCLS Directory (session folder). A UCLS Directory can have other UCLS Directories as subdirectories and/or sessions that belong to that folder.


This XSD defines the schema for a session.

Generating code from XSD

Many languages support automatic code generation from XSDs, and this typically will consitute the easiest way to quickly begin working with UCS and UCLS content.


If you plan on building tooling for UCLS library processing, you could auto-generate .cs files for them with the xsd.exe that comes with a Windows SDK. Below is an example:

$ "C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6 Tools\x64\xsd.exe" /classes "universal-capture-2.0.xsd"

This will output a universal-capture-2.0.cs file you can use to serialize/deserialize a UCS xml file.


lxml provides the necessary functionality to do this fairly easily. Please see the validator tool for an example of how to do this. Note that ucls_directory.py, ucls_library.py, and ucs_session.py were auto-generated from the schema XSDs using generateDS.py that you can get from https://pypi.org/project/generateDS. See those files for the command line used to generated them.

UCLS Library Samples

The package comes with sample UCLS libraries to provide examples of what UCLS and UCS xml files look like and how they're structured. Please see the samples folder

All sample media files are derived from https://github.com/mathiasbynens/small

Running the Unit Tests

This package contains a unit test suite via pytest runner to validate the tooling against provided test content. To run all the tests, do the following:

$ cd <package folder>\tools\validator
$ pytest

You should see an output like the following:

test_validator.py ......                                                 [100%]

========================== 6 passed in 3.47 seconds ===========================