Re: [Avid-L2] Europe here calling: p50 -> p25 - i25

I'm wondering if some terminology has changed a bit.  I had always thought of field dominance as which field an edit occurs on.  Field one or field 2 can be adjusted on switchers and on tape machines back in the linear and tape delivery days.  I have always set systems to edit on field one and I thought that is considered field dominance.  Then there is field order Upper or Lower and I just realized that has to do with if the interlace starts with an half or full line.  For some reason I had never known exactly what upper vs. lower but knew SD was lower and HD was upper.  I had thought it was whether the file had Field one first or field 2 stored in the order of data.  Here's something a quick google found but I still think this is an incorrect usage of Field Dominance as they are using it to discribe Field Order.  From a search"

"Dominance simply refers to the which field comes first. Upper field means the odd line comes first. Even field means the even line comes first. You cannot reverse this order or your video will fall apart.Dec 19, 2008"

Meanwhile back to my basic quandary.  If something is shot 50P that is 50 whole frames per second.  Wouldn't the best conversion to 1080i 25 be to take each whole frame and put it into a field of the interlaced 25?  Each whole frame of the 50P is from a unique moment in time so there will be temporal displacement.  This discussion seems predicated on an assumption that for example the 00 and 01 frames can be blended because they come from the same moment in time but as far as I know they don't.  If the 00 and 01 are coming from the same moment in time that would be 25 psf wouldn't it.  So if 50P is really 50 unique frames separated by 1/50 of a second it seems to me any combination of frames would create frame blending. 

As I write this I think I'm realizing that what the core issue is one of what I traditionally think of as Field Dominance and not that if the edit doesn't happen on Field one consistently that's when you get spiit frames between two different shots.  It sounds like you need something like the color frame setting of linear bays and IIRC Avid had a toggle for color frame as well.  Gee I guess at least the concept of SCH still has some relevance even if it's technical necessity no longer exists.  So it would be nice if Avid could invoke something like a for to only edit on even frames when the Rec Timeline is TC1=50P.

Now back to my thought that if the conversion from 50P to 25i was done taking each whole frame and putting it into a field then it wouldn't matter what field the edit happened on as each resulting interlace field would come from a whole frame.  So why can't the conversion work this way?  It seems as Mark pointed out 2nd field edits would mess up a subsequent progressive conversion.  Once again there is so much for a progressive streaming source cadence and image quality issues are disregarded.

Now that I think I've wrapped my head around this a bit I don't understand why the 1 frame offset in your multigroup would effect this at all.  It seems to me the split frames are a result of where the edit on the record timeline is and has nothing to do with the source material side of things.  Am I missing something there.  Now if you are battling the field dominance of what the switcher put out I have seen that mess things up.  Does you program feed file have switcher cuts that are randomly on odd and even frames in 50P time code?  Switcher in the past, and must still do, had settings to cut on Field One or Field 2 or unspecified so when you hit the button the next field or frame in the case of 50P will change shots.  This goes back to the annoying trims of a frame to avoid a flash field.

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