Interlacing Frames -> Fields

Compositing
1

OK. I have a non-interlaced, composited sequence of CGI frames rendered at HD video resolution (1920 x 1080) that I want to interlace. I have 60 full-sized frames for each second of output with the intention that frames 1, 3, 5, etc will become the odd fields and frames 2, 4, 6, etc. will become the even fields. (I'll be throwing out alternate scanlines). At the bottom of my Shake tree there is a node representing the final composite of FRAMES.

It seems that I could accomplish the interlace step by spliting two noodles from here through two timeX nodes to the two inputs of an interlace node. The first TimeX node would have the expression (time * 2 -1) and the second would have the expression (time * 2). I believe this would present the interlace node with frames 1+2, then 3+4, then 5+6, etc. Seems like it should work, but it doesn't.

Anyone have a more standard way of doing this, or can give me some insight why the node tree I just described fails?

      final comp node
                /\
               /  \
              /    \
             /      \

TimeX node TimeX node
(time *2 -1) (time *2)
| |
| |
| |
V V
interlace node
|
|
|
V
file out node

Thanks,

Michael

2

Your theory for the timeX expressions is correct but you have to feed each timeX with a separate tree.
I would suggest rendering the comp and then bring it back in with two fileins, one for each timeX to do your interlacing. The other way is to duplicate your comp tree and feed those into the timeX's.

3

found this under the file-in node... thought it might be a bit easier:

Creating Interlacing From Non-Interlaced Source Media
You can also use the reTiming parameters to interlace previously non-interlaced media.
To create interlaced output from non-interlaced source media:
1 With a FileIn node

4

QUOTE(mloomis @ 05/17/06, 01:12 AM) [snapback]237477[/snapback]
It seems that I could accomplish the interlace step by spliting two noodles from here through two timeX nodes to the two inputs of an interlace node.

my understanding is that using two TimeX nodes will cause problems, so try using 2 FileIn nodes, offset one by a frame and only read in every second frame...

++ christoph ++

5

QUOTE(zem @ 05/17/06, 04:41 AM) [snapback]237509[/snapback]
my understanding is that using two TimeX nodes will cause problems, so try using 2 FileIn nodes, offset one by a frame and only read in every second frame...
Yes, Timex nodes propegate up the tree and will cause issues if you don't understand what they are doing.

So for example you have a filein that goes from 1-122 and then put a timex node and tell it to stay at frame 24, well you would think that if you were to do any branches before that timex, it would act like like it still has frames 1-122. Unfortunatly it doesn't work this way. Anywhere above that tree the filein is still at only frame 24.