The translation mechanism that allows a user to override the name of the DDR property used by a transcoding action is just a particular use of the generic options mechanisms.

There is no apparent reason to separate DDR properties from generic options. The only difference is the need to have checkProperty AND checkOption, because of the specificities of a PropertyRef creation within a DDR.

In short, why is a "properties" subarray needed within the "options" array?
I'd remove it, and replace code such as:

[[
$properties = $this->getOption('properties');
$is_mobile_device = $this->getPropertyValuePr($properties['mobile_device']);
]]

by

[[
$property = $this->getOption('mobile_device');
$is_mobile_device = $this->getPropertyValuePr($property);
]]