Enumerator. List modes used to overlay boxes and text.
MODE_CPU : Selects CPU for OSD processing. Works with RGBA data only.
MODE_GPU : Selects GPU for OSD processing. Yet to be implemented.
MODE_HW : Selects NV HW engine for rectangle draw and mask. This mode works with both YUV and RGB data. It does not consider alpha parameter. Not applicable for drawing text.