I think this question has been asked before, but I am still not comfortable with it. I understand the difference between these two color spaces, but how do I know what to choose when working with DCP o Matic? 

How can I check the color space of a video file?

And what do I do if I do not know it? 

When working with HD Material, is Rec 709 the common color space? 

When I export from Premiere to Avi uncompressed, TIFF sequence or H264, how do I know what the color space is? 

Any answer is appreciated! 

Thanks

Andi