NTSC/PAL Interlacing Renders

[gtcable]

I do animation for television.
When I export Maya animations I set them up interlaced NTSC.

How about the same option in Anime Studio renders?

[Bones3D]

Hmm... why not just export to an image sequence and use an external editor to perform the interlacing on the sequence? I don't know very many industry workers that use actual movie files from the source program in the final broadcast output.

[gtcable]

Correct me if I'm wrong, but AfterEffects can not detect movement in a stationary QuickTime. How would it know to interlace a moving arm over a static leg?

[slice11217]

Correct me if I'm wrong, but AfterEffects can not detect movement in a stationary QuickTime. How would it know to interlace a moving arm over a static leg?

You could try rendering out of AS at 60 fps and then bring your sequence into AfterEffects at 30 fps, time remap the sequence to fit the time length of the shot, then render out at 29.97 interlaced. That should work.

[IsraelRN]

You could try rendering out of AS at 60 fps and then bring your sequence into AfterEffects at 30 fps, time remap the sequence to fit the time length of the shot, then render out at 29.97 interlaced. That should work.

Wouldn't this double the render time?

[artfx]

2D animation can not be interlaced. It doesn't matter what program you use. You can output an NTSC compliant stream from AS, or After FX or any other program, but the motion will never be interlaced because there is no motion.

Maya is able to interlace motion because it treats the camera like a real camera, and the object like a real world object. It does sub-frame calculations for FX like motion blur or rendering an interlaced stream. In 2D it's just a bunch of images, no different if it approximates motion or if there was something completely unrelated on every frame.

You can cheat it, and do 60 fps as was suggested, but what would be the gain?

[Rhoel]

2D animation can not be interlaced.

Actually it can be.

To do it in AS, you must double the frame rate and treat the frames as fields. Programs such as Combustio will interlace the "frame fields" back into an interlaced stream - It's something I have had to do in the past, when a character action was unacceptabley strobing. But for 99% of animation, it isn't necessary. Cinema and the quality end of HDTV uses no interlace.

Render times do double and the time you need to convert the frame-fields to interlaced also takes time. Its not neccessary to do it foe all scenes but sometimes if the action needs to be smoothed out then you have no option.

Just be careful of you output tape format - some are odd field first others eve first. DV for instance is the opposite if Digi. Most are field 1/odd. Do a test first,

Rhoel.

[artfx]

As I mentioned:

You can cheat it, and do 60 fps as was suggested, but what would be the gain?

But it will not be properly interlaced.

If you shoot one second of video of, say, a wall, with no motion and load the images into a program tha shows you the different fields which make up each fram, you will notice that the information contained in two fields is not the same. There is a slight vertical offset to the information on each scanline. This is why small horizontal details tend to disappear with deinterlacing video or fade in and out if the line is slowly moving vertically.

A 3D program like Maya, treating the virtual camera as a real camera and using sub-frame calculations will properly render this vertical offset into each scanline of the fields of each frame, creating a proper interlace. If however you use a 2D program and draw 60fps you have 60 full resolution progressive frames. When you convert it to 30fps (29.97) for 'interlacing' this vertical offset associated with video will not appear, but the same information will appear on each scanline from a vertical perspective as though it were a progressive frame. This is not to say it wouldn't help smooth out fast motion. It certainly will, but it will not be a true interlace render such as can come from a 3D virtual camera like in Maya or other 3D apps. This is why I consider it a cheat.

[Rhoel]

But it will not be properly interlaced.

Not sure the guys at Combustion will be too happy with your remark - their inter-lace and de-interlace software is very advanced. .

The Combustion formula is precisely the same as used b the 3D guys like Maya ... they renders two fields then combines them. It does not calculate the off-set on-the-fly during the render: To calculate the line offset and mesh them during the render would cause a heap of undesirable artifacts as well as increasing the render time exponentially. So at some stage there will be 60 fields rendered in 3D.

But to say a converted 60 frames is not true interlace is just plain wrong: Digital camera run the CCD's at 50 and 60 hz then used software to encode the interlace. The same is true for all 3D packages. The same is true for Mirage, Quantel and Combustion.

And to say the original fields are different per say just because it came from Maya is technically wrong. IF you use mathmatical formulate to co-join images then it negates the source application.

artfx wrote: There is a slight vertical offset to the information on each scanline.

My understanding this is a problem unique to NTSC. Its also why the rest of the world adopted the technically superior PAL (Phase Alternating Line) standard specifically to overcome the defects of the NTSC standard which has too many unwanted artifact problems. Fortunately, the advent of HDTV means NTSC and its insane 29.97 dropframe codex will be confined to history along with the 8-track.

As for interlacing in respect to animation, it's worth taking a step back and taking a look at how animators work. Most people are drawing at 12 fps (one drawing, two frames). The argument over interlace is therefore largely acedemic. However it is worth considering that the actual information recorded on DigiBeta, SP or DV will be interlaced at the online mastering stage, irrespective of the original video file. That means a 25/30 fps progressive video file will get field doubled.

AS uses IK and bones in exactlythe same way as Maya and Max; So animating at 60 fps (50 in my case as I'm on PAL), can is some special instances produce very smooth and correct inter-field positional information. Fast pans and other quick action do benefit from field rendering.

Rhoel.

[artfx]

I can't speak for Quantel nor for Combustion past version 3, the last time I used it, but I know very well the interlace/deinterlace of Mirage and worked closely with them on it. In Mirage, if you load a fielded project originated on video or in a 3D package and flip through the fields of a frame using the A and B buttons, you will see the vertical shift commonly associated with NTSC, which I agree is a horrid format. If, however, you take 60 progressive frames and convert it to interlaced 29.97 frames, then flip through the fields, that vertical shift will not be there.

Now I guess this should be considered better since the vertical shift does result in unwanted artifacts of NTSC as you mention. Perhaps this should also be called "properly" interlaced, since it would be a cleaner result. Maybe I should have said the results from Combustion wouldn't be "traditionally interlaced".

When I worked on a project at Rainbow Studios, we chose to render fielded output from Lightwave 3D and we rendered to DPS PAR or Perception cards. In so doing the result was interlaced with the artifacts commonly associated with NTSC. Thin horizontal details would fade in and out or stair step etc. This is what I have come to expect from interlacing, which I call bad. This is also why I always go after the film look in my projects. I prefer motion blur.

So I must revise my terminology. I was wrong to say that 60 fps conversion wouldn't result in proper interlaced frames. I just hope all interlacing should sink into tar pits before I ever have to worry about it again.

[J. Baker]

Export your work in 24fps. When you open it in a mpeg encoder, select the option "24p -> NTFS (3-2pulldown)". This will give you a 29.97fps mpeg that's ready for any dvd authoring software. This is how it works in ProcoderExpress anyway.

[J. Baker]

I just wrote the following tutorial...
http://www.lostmarble.com/forum/viewtop ... 1809#31809

[Fazek]

In my works, I never used interlacing for the 2d animations. I think it is not required. But for example on the end credits of a film, when the text scrolls through the screen, I must use it always. Rendering in double framerate and full resolution has an advantage: in the basic way of interlacing, the first row is from the first image, the second from the second, the third is again from the first and so on. But an advanced algorythm can calculate the rows from the combination of the two images, and together with some other intelligent filters getting a smoother (not vibrating) but sharp image. This is a serious problem in the video encoding and compression. Usually this is exactly what good encoders do better than others.