View Full Version : 1080p25 or 1080i50?
10-02-2008, 12:02 PM
This may be a very stupid question... So is the 1080 output from REDrushes/REDAlert/RED Cine 1080p25 or 1080i50? Everyone seems to be talking about 1080p, but when I import the clips to Final Cut, it says there is a field dominance, which means it would be 1080i50. I know there are no fields created in-camera, but does the conversion make it into 1080i50 (with identical fields) to make the file size smaller, or for some other reason? Or have I just misunderstood something here?
We're trying to output prores files for chroma-keying, and I have understood that chroma-keying interlaced material is not a good idea. And we wouldn't want to go to 720p because of loss of resolution.
Thanks in advance!
10-02-2008, 12:33 PM
We always output progressive.
10-02-2008, 01:46 PM
Ok, that's good news. Any idea then why FCP shows there's a field dominance (upper)?
10-02-2008, 02:34 PM
Because FCP has no way of knowing and just guesses?
10-02-2008, 02:49 PM
I don't think it even guesses. I spend half my time now days changing clips I import all day long from Upper to None. I wish Apple would let you set default as everything I do is progressive!!!!
10-03-2008, 05:25 AM
Why no change them all at once? Yo can change this setting with more than one selected…
10-03-2008, 10:21 PM
A very annoying choice from the FCP developers indeed.
Back in FCP 4, this wasn't a problem: When you dragged a clip tagged as interlaced into a progressive sequence it had the exact same result as if the clip was tagged as progressive.
This enabled the operator to chose the deinterlace algorithm, like the excellent deinterlacer from Mr. Nattress. Or enabled you to mix progressive and interlaced, like rendering an interlaced credits crawl on top of progressive material.
Starting with FCP 5, Apple implemented automatic deinterlacing, with no notice whatsoever...
I first noticed this when I opened an older large 1080p25 project after upgrading to FCP 5. After re-rendering my sequence, the vertical resolution was cut in half by simple field doubling. Awful. I digitized from HDCAM SR thru a Blackmagic card and the 1080p25 preset was set to upper field dominant. Well too bad. And it doesnt make it better that the item properties tool only handles 128 clips at a time...
I actually spoke for 30 mins at IBC 2006 with one of the FCP developers, and he said it was the intended behavior. That was back when importing 1080p25 P2 media was tagged as upper field as the data stream is infact 1080i50.
I can see this would be usefull in something like iMovie, but FCP should leave the choice up to the operator, or at least make it easy to remove.
Only solution is to select less than 128 clips in the sequence and right click item properties and then change them one by one.
I have spoken with Deanan two months ago about the problem, and asked if it was possible to write the progressive field dominance into the metadata as Apple does internally (And Sonys XDCAM transfer tool also does correctly) as neither Red Alert or Red Rushes manages.
I believe they are waiting for information from Apple about the API to use, and exactly what info to write. Which isn't surprising.
Btv. All Video resolutions that has support for interlaced formats default to upper field dominance if the Metadata isn't written. That includes: 1080, 576, 480
11-20-2008, 02:05 PM
When exporting from Redalert of Redcine I'm experiencing fine dancing grain in SOME of the shots, mainly in the grey parts. I suspected some kind of interlace problem, discovered this thread and changed settings of all my shots.
The grain however did not disappear.
Any suggestion to what's happening here? Seeing some material of others I discovered the same problem.