Audio demultiplexing: fix little endian case

* It was an offset problem.
InputAudio: refactoring readNextFrame with subStream

* Suppress comments.
* Add todo.
VideoDesc: refactoring - rename local variable
VideoDesc: refactoring - reorder includes
AudioDesc: refactoring - reorder includes
Ratio: add default constructor
VideoFrameDesc: add default constructor
OutputVideo: refactoring - rename local variable
Merge pull request #31 from cchampet/dev_subStreams

Fix audio demultiplexing