Re: [Tracker] Add support for OMA DRM Content format

["Lin, Mengdong" <mengdong lin intel com>]

Supporting DRM formats usually involves proprietary multimedia framework extension (such as the DRM-aware 
GStreamer plug-in) and low-level proprietary HW/SW support. It seems better to enhance GStreamer extractor 
than writing a new DCF extractor, because:
- If it depends on GStreamer, it cannot extract meta data faster than the GStreamer extractor.
- If it does not depend on GStreamer, it has to use proprietary code to do decryption and cannot be open 
source.
- OMA DRM is an open DRM scheme for mobile market and the underlying multimedia frameworks like GStreamer can 
support it by installing extensions. GStreamer extractor can try using GStreamer framework to get metadata at 
first; if nothing can be got because no GStreamer DRM extension is installed, the extractor can do something 
by itself.
 
Thanks
Amanda