To interlace or not to interlace

[Chad Warner]

We create pretty much all of our animations for DVD's that will be shown on TV screens. As such, we've been interlacing all of our footage so it looks better on a regular TV screen (not progressive scan).

 

My question to all you experts out there is this: Is there a better way to go about doing this?

 

Interlacing takes twice as long to render, and the end result is only good if you are viewing it on a standard TV...not a flat panel or a computer screen. Does anyone have experience with software that will take regular footage and interlace it after the fact?

 

Thanks for any input.

[omar]

trus me you don,t need to interlace .

it wold take mor time to render ...

you onley need to make sure your setting in max is PAL or NTS

and render to sequince and then interplate them with AE and make sure

the frame rate is set to 25 for PAL or 29 for NTCS this the most importan step

also make sure your set the field order in max to ODD in the prefrence and scale the saturation

[Lester_Masterson]

I too am having an interlace problem. In the old days of rendering to Beta / VHS, we always rendered ODD fields. I assumed this to be true for DVD as well.

 

Viewing on a new Sony DVD player, it looks great. Playing on a first generation Hitachi, utter crap.

 

Switch the fields to EVEN, looks great on the Hitachi, horrible on the Sony.

 

I certainly don't want to have to render 3 versions (Interlace EVEN, Interlace ODD and Non-Interlaced), I'd never get anything out the door.

 

Has anyone had this experience too? Or did I get the only DVD in the Western Hemisphere that likes EVEN field Interlacing? ;(

[Chad Warner]

I've always done odd interlacing. I'm trying to figure out how to get rid of interlacing all together though.

[John Dollus]

A couple things regarding interlacing:

 

It is only effective if it is interlaced as the images are rendered since it relates to the relative velocity of motion within the scene. For example, an object closer to the camera will have more seperation between fields than an object in the deep background.

Interlacing footage in post will not achieve the same result since the image is reduced to merely pixels at that point.

 

With progressive scan becoming mainstream, interlacing is not as important as the 'old days'. You do, however, need to know what equipment will be used and make sure it is setup properly. For instance, many newer DVD players have progressive scan features but they only work through component output and not through the S-video connection. Also, some displays need to be configured to accept progressive signals or they try to process the image as if it were interlaced. A good example would be 2 pieces of showroom equipment today - a progressive scan DVD player and a progressive-capable consumer display like an LCD or plasma. Both have internal circuitry to improve the picture quality but you don't want both to be active or the signal will be greatly over-processed.

 

Funny thing, some of the newer displays with builtin line doublers produce better images with interlaced footage than using a progressive scan signal as the original source.

 

If it is an old Hitachi, you might double check the configuration menus to make sure progressive scan is turned on. My old Toshiba is quirky this way. It has a Genesis deinterlacing chip that will try to deinterlace a progressive scan DVD even if it doesn't need it which leads to a lousy image. Of course, if the progressive flag isn't set when authoring the DVD, that will mess with it too.

 

Here is a very old article but it explains the varied deinterlacing results from many consumer DVD players (maybe your Hitachi is in there):

 

http://www.hometheaterhifi.com/volume_8_3/dvd-benchmark-progressive-shootout-2-8-2001.html

[William Alexander]

It is only effective if it is interlaced as the images are rendered since it relates to the relative velocity of motion within the scene. For example, an object closer to the camera will have more seperation between fields than an object in the deep background.

Interlacing footage in post will not achieve the same result since the image is reduced to merely pixels at that point.

 

 

WHAT? How do they digitize film if it's not interlaced-rendered twice for fields....single image rendered out to fields, we see it all the time, well used to

 

Interlacing, my understanding, is part of compression for broadcast a way to get 2x the information out for the same signal bandwith. Its a way of encoding picture information and most major compositing apps like Shake, Digitial fusion, After Effects deal with rendering single images out to interlaced with out too many problems or issues...that don't naturally come with interlaced TV picture.

 

Please correct me if I'm wrong here

WDA

[Lester_Masterson]

John: Thanks for the link. This "will" come in handy.

 

Now I am even more confused than ever. I used to think I understood interlacing for VHS and Beta, but now, this new aspect of Plasma, LCD and DLP throws everything out the window.

 

So, How do Movie Companies make a movie look good on PC's, Mac, NTSC boob-tubes, LCD and Plasma screens? Is there some super detector mode that the DVD says "Oh, so that's what that lump on the couch is viewing me on...let's just switch modes..(click,grind)...and...(click,click,whir)...voila!" ????

 

I think I'll just start sending my animation to clients via "flipbook"

[Chad Warner]

I think I'll just start sending my animation to clients via "flipbook"

 

either that or claymation:p

[John Dollus]

WDA: Film is a completely different animal.

 

Go ahead and run a test for yourself. It's fun!

 

Create a scene with two long, thin cylinders like lamp posts.

Put one about 10 feet from the camera and another about 100 feet or so away.

Now animate a free camera past the two objects at about 30 mph or so (just so you get a decent velocity).

 

Render the scene out with fields and look at the individual image sequence to see the difference.

 

This is how you get the 'maximum' benefit of interlacing with NTSC footage.

 

Now render out the same sequence as frames and interlace it in post through whatever app you prefer like After Effects and compare the same two frames.

 

The footage will be interlaced but there will be a difference in how the motion is handled.

 

This is also a good test with large repetitive patterns like brick!

[Chad Warner]

John-

 

Since you seem to be the resident expert, do you interlace your animations?

[John Dollus]

The last couple animation projects I did at home happened to be for web use so just frame rendered but I prefer to work with fields for a couple reasons:

 

1. I use a Velocity DDR at home which happens to be designed with fields in mind.

 

2. I prefer to author to the lowest common denominator which is still CRT display so far. Even the best prosumer progressive scan DVD players still pass 480i footage as the default and unless I am absolutely certain the client is a tech-savy video enthusiast, that would probably be the way they hook it up. If you ask them if they have an HDMI cable and they answer 'oh, yeah - that's how my mouse is connected', then definitely interlaced.

[Chad Warner]

That's not really what I wanted to hear, but I guess if that's the way its got to be, then that's the way its gotta be.

[William Alexander]

WDA:This is how you get the 'maximum' benefit of interlacing with NTSC footage.

 

I agree there...but as soon as you have to work it heavy in post, life begins to fall apart and that's where it becomes just like film and many times it's just best to de-interlace and let the native interlacing of the post. If you have the power and time sure rendering it out 60 frames interlaced per second is best. Also using 3:2 pull down from 30 frames is alleged to help also.

 

Cheers

WDA

[Ernest Burden III]

Not even experts with large brains have a single answer. Here's a cgtalk thread that attempts to reach some conclusions:

 

http://forums.cgsociety.org/showthread.php?t=345102

 

I'm struggling with output formats when the end result will be seen on a computer AND probably put on a DVD. The PAR--pixel aspect ratio--is kicking my butt.

[John Dollus]

http://www.alparysoft.com/products.php?id=8&item=6

 

This is a really inexpensive plugin for After Effects/Premiere that does a good job of deinterlacing footage. It's good for repurposing footage from fields to frames.

There are many others but this one is only $25.

[Chad Warner]

Not even experts with large brains have a single answer. Here's a cgtalk thread that attempts to reach some conclusions:

 

http://forums.cgsociety.org/showthread.php?t=345102

 

So the expert there says no fields ever, while the expert here says yes fields. What's a renderer to do?

[William Alexander]

It's all very subjective, imho

 

The best is 60 frames (full)...gives 30 odd and 30 even. Striaght out to post or final output. if it's a 15+ minute running 29.97 life gets interesting. To get it out NSTC or PAL, your compiling app or post app must convert from 3:2 to get 24-25fps repectively. Or you could render out 48 or 50 frames odd an even combined and compile. Now if your doing compositing the full frames (image sequences) allows you to pretty much do whatever keeping in mind the PAR, scaling, blur all need to repsect the non square pixel aspects. Now if the footage comes in 'interlaced' odd & even frames having 1/2 of the vertical aspect data life totally melts down in post and gets tricky, you need to de-interlace in do the compositng and interlace back out...making the compositging editing apps the general workhorses for output to TV formats. Generally that is accepted and has very few issues, that aren't normally present in digital/tape/film converted to broadcast quality. Of course if you have access to high level DDR and mastering devices much of the quality conversion can be done there, stand alone proprietary software or with the likes of Final Cut Pro, which for digital media has many specilaized tools for both input and output of Digital video. Those tools start to shine with aquiring green screen footage.....on and on....and on...... a very convoluted non linear thought when applied to "all" cases LOL

 

This discussion here is a very specialized slice of the broader CGVFX world, where so many other factors, cost, render times, can and need to take a back seat to perfection, there are many time tested work arounds. But the quality is all targeted to the end user/use....very subjective aka it's good to know many ways of working the system including super duper time consuming anal ones that in the end only videophiles will ever notice or care about...over the actual intent of the video-to convey information, thought, concept ect.

 

Is there one answer, imho no. It's an art form, albiet very technical, that requires careful balance, judgement and expereince to juggle all the factors.

 

Rambling concluded

WDA

[Lester_Masterson]

Thanks to everyone for the input. There is lots to think about now.

 

Last question:

 

Would recording to DVD-R or DVD+R make any difference?

 

I'm going to guess no, but ...

[colinsmith]

I think it's interesting this is sitting next to a "FIlm Quality Rendering?" thread.

 

Isn't rendering progressive with a 50% motion blur the biggest factor in the choice of format that'll give you film type motion in the finished animation? Obviously you need cinematic lighting and camera moves to complete things, but I don't see much advantage to any other choices than 25p or 30p (deending on pal/ntsc).

 

Again it's interesting that true progressive frame recording is a huge deal in the video camera world, and in 3d we have that as a "click the box" option and are not sure whever to use it

[Chad Warner]

Based on what I've heard here and in the "film quality rendering" thread, I tried putting motion blur on an animation, and it turned out really bad. Everything had a shimmer to it, like the blur wasn't consistent. I used Viz's default motion blur, on the image with a value of 1. Is there another way I should be doing this?

 

Thanks,

 

Chad

[William Alexander]

Chad...is the shimmer only from the motion blur or something else, like AA?

 

C4D for example has a PAL/NSTC AA filter that seems to help with the 'sparklies'. Haven't opened Max in 3 months, just don't remember if there is a similar filter

 

WDA

[Chad Warner]

Definitely only from the motion blur. I'm using Vray as a renderer, and have not had this problem before.