In order to speed things up on my current project I decided to digital cut to HDCam and recapture to ProRes422 which is what we have to deliver.  One reel is a matte key reel with mostly black and some black on white hicons.  The whole tape is 46 minutes but it looks like the mxf file created in Avid is only a little above 3 gigs.  I can open the file in QTPro7 and it seems to be self contained duration approx 46 minute ProRes422 but the bit rate 11.14 mbits/sec.  That seems low.

Is this even possible?  I captured baseband sdi into Avid to ProRes422.  I would expect a much larger file.  Is this because ProRes is a variable bit rate codec and most of the tape is black and white so it compresses to next to nothing?  I'm capturing the foreground reel now and will see how big that file is.  I would have expected the file to be way bigger like a gig a minute or maybe half that for ProRes422.  What am I seeing?  The effeciency of a variable bit rate codec or something off?