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pilkiwilky
04-22-2005, 09:40 AM
Hi, I have a TV spot in LW and when I took it into the station they asked me if it was rendered LOWER field first or UPPER. I told them it was not rendered in fields. He then told me I should always render in fields as output was to 60i monitors. Is this true? He said I would get less flicker on the image. I rendered with FPRIME which I don't think renders fields? PLEASE someone explain all this to me.

Thanks

dgon64
04-22-2005, 01:07 PM
The short answer is for NTSC video, every frame is comprised of 2 fields ( basically the same picture drawn twice). This is how t.v. works ( search the internet for as to why if you're interested ) so when creating an animation for t.v. ( NTSC ) video you must turn on the field-rendering option in Lightwave ( broken in 8.2-promised to be fixed in 8.3-I think ) otherwise you are only displaying half the information the t.v. needs to properly display the animation-hence the flickering. Now, each frame rendered in such manner will be comprised of an upper and lower ( sometimes referred to as odd/even ) field. When playback of video begins, one field is drawn first-then the second (near simultaneously) but there is no "carved in stone" preference as to which field begins the playback. There'a another thread somewhere on this forum which explains the uncertainties of which field to render first. That's why you were asked as to which field was first-because you need to render 29.97 frames per second for NTSC video ( rounded off to 30fps for descriptive purposes because in reality true 30fps is computer video which is what you have -not suitable for t.v. ) which works out to 60 fields per second therefore it is technically referred to as 60i video ( the i stands for interlaced which is what happens to the 2 fields when drawn on the t.v. screen-they are interlaced to produce 1 frame of NTSC video. How about that for a short answer!

pilkiwilky
04-22-2005, 01:11 PM
So you are saying you CANNOT render in fields in LW 8.2??

What about FPrime? can you render in fields?

UnCommonGrafx
04-22-2005, 01:20 PM
It's actually a two-step process; just turning on Field Rendering won't really get it. You also have to change your fps to 60 - This seems to be a toggle within LW.
After that, you can see that it's doing it right by advancing a frame at a time where you should see alternating fields.

pilkiwilky
04-22-2005, 01:33 PM
60 fps?? So doube the frames to render>??

That sucks! Is that really the answer?

UnCommonGrafx
04-22-2005, 01:39 PM
Chuckle,
And thus the reason it's not in vogue. Regardless, this is what one must do to achieve what one must.

pilkiwilky
04-22-2005, 01:41 PM
so will that really take double the time still if it is only rendering one field at a time (50% of the image) wont it just be the same?>

And what about FPRIME - do you know how to do it using that?

thanks o wise one!

Lukesutherland
04-22-2005, 02:00 PM
Hi, I work in UK, so it's PAL (25 fps) but still same concept -


I only render in fields when there is a lot of movement, if its a fairly slow moving thing I do frames.

I DONT however, render at 50 fps - 25 works for me - adds a little render time but not too much - I have never heard of the double frame rate used that way - I have heard of doubling frame rate with frames then interpreting that footage at correct speed (25 or 30) in a compositing program (after effects) then rendering with fields.

The benefit of this is you still have all you 'frames' intact.

Whether you render even or odd field first is easy to check with a test render to your destination playout device. The wrong order will look like it's going forward then back etc.
An exception to this variability is DV - it's always lower field first or odd. - if you capture dv footage thats what it'll be or if you're outputting using a dv card do it this way too.

Our DPS reality system at work is upper.

Lukesutherland
04-22-2005, 02:02 PM
I am however using 7.5 - so the above statement may not apply to 8.+ but I would be surprised...

UnCommonGrafx
04-22-2005, 02:10 PM
There was test material out there for this...

Actually, when you do it as you state, Luke, you are just doubling frames for any vidclip in the scene. Also, let me be a bit clearer: my needs for FR were that the VideoClips I was importing were also field rendered on the surfaces, not doubled, full-frame, as I alluded to above. For just motion, yes, this would work.
So, based on this, for FR to work properly, I had to switch the FPS from 30 to 60, letting LW double the frames as it's wont to do at that stage. And the rendering times for one frame is still the same as it is for ... one frame. ;) Yes, under this scenario, rendering of halfs in not an increase in time, so no real penalty.

No, FPrime can't be used for such rendering; it's a full-frame renderer.

js33
04-22-2005, 02:11 PM
It's actually a two-step process; just turning on Field Rendering won't really get it. You also have to change your fps to 60 - This seems to be a toggle within LW.
After that, you can see that it's doing it right by advancing a frame at a time where you should see alternating fields.


???? Who told you that? You don't need to render at 60fps to render interlaced frames. Why do you think LW does an A and a B pass when field rendering is turned on? It is rendering each field per frame in the same file.

Also while interlacing is probably a good idea for TV it's not absolutely necessary. How about all the movies shown on TV? They are from a progressive source (film) and displayed fine on a TV.

Cheers,
JS

UnCommonGrafx
04-22-2005, 02:22 PM
Check my post above...

LWConnect, http://toastergarage.com/lwconnect, is the product I was working on when this was shared with me. For us to be able to maintain field rendered material throughout the render process, this was shown to be a necessity. Give it a try and you can see it happen.

Put an interlaced image/clip on a surface and render at 30fps. Doubled frames when you play it back.
Set it to 60fps and you can advance a frame at a time to see the de-fielding process at work as lw will show you each field on its on frame. That is to say, upper will be shown first - frame 1, then the lower field will be displayed - frame 2, cycling through the fields as you go. This was quite funky the first time I saw it. Makes sense but still, kinda funky.

Field Rendering for what purpose is where an answer will help or not. Mayhaps I've missed the gist of what was desired here but this is the one piece of info I've come to appreciate about the topic through great pains. :rolleyes: So others don't have to.

dgon64
04-22-2005, 02:40 PM
Yes, you are right in saying that 8.2 does NOT do field-rendering ( search this thread in this forum ). Newtek has promised to fix this in the next update (8.3 ). So it shouldn't be too long now. Patience-anyday now!

NanoGator
04-22-2005, 07:57 PM
I cannot speak for 8.2 since i have not done field rendering with it. I can tell you, though, that with Lightwave you shouldn't have to do 60fps rendering.

As for longer renders: Actually, even when it's working correctly, you WILL get longer renders when field rendering. The reason for that is motion blur, for example, still has to do all the passes. What LW does is it does cut the frame in half (i.e. you are effectively rendering at 720 by 240), but you still have the other processing passes to perform and they chew up time. I wouldn't say it's 2x, but in some cases it's 1.1x, sometimes it's 1.5, sometimes it's even 1.8

You don't HAVE to render in fields with NTSC, but if you want smoother motion you should. Sadly, though, different output mediums require different settings for Lower or Upper field first. My memory's fuzzy on this but when I worked on my demo reel last year, I found that for burning to DVD I needed one setting but for working in DV I needed another. I really wish I could, instead, tell LW to render out the frames as though they're progressive, then let After Effects decide how to work. However, there are serious technical issues with this and I can understand why it doesn't work that way.

Fun stuff.

Tom Wood
04-23-2005, 04:20 PM
I fought this issue for some time and finally gave up and rendered everything in progressive scan (frames) all the way through the pipeline. (LightWave>Mirage>VT3>DVD Workshop/DVCAM tape) I'm still using LW 7.5c and you don't have to double the frames. LW adjusts for that when it is set to fields - it does a double pass per image frame to accomodate the motion change from field to field.

But I found that the fields setting helped the side to side motion while harming the up and down motion. Naturally, progressive scan (frames) did the opposite. :rolleyes: And each program in the pipeline would also add its own distortion if the ordering was reversed from what it expected. As a compromise, in LW I use dithered motion blur and the soft focus camera setting to fuzz things enough to make the motion in both directions look okay.

I've yet to see a definitive answer of which is which regarding upper/lower and odd/even. Upper is the set of alternating fields starting with the topmost field and lower is the alternating set starting immediately after the topmost. But odd/even is in dispute because some numbering systems use 0 as the number of the topmost field (even) and others use 1 (odd). :confused:

TW

dgon64
04-23-2005, 06:15 PM
I've also never found an answer one way or another so it's good to remember just in case you're asked ( by person or software ) which was the point of the original post-so I hope we haven't totally confused him. It's not that hard to grasp, but this thread seems to show again that this becomes a chicken and egg scenario-which comes first? Odd/even-lower/upper-I guess it depends on who or what is asking.

Gui Lo
04-23-2005, 07:27 PM
This is interesting to me since I am doing a tv commercial at 25fps. The client has not asked for field rendering.

However I am a bit confused by what has been said with some outright contradictions.

IMHO the best thing for pilkiwilky to do is to submit several setting tests and see which setting works for the client.

Rich
04-23-2005, 10:03 PM
I want to clear up confusion on 8.2 not rendering fields. If you see the bug report it says nothing about LW not rendering fields.

If you go to the bug workshop thread (http://vbulletin.newtek.com/showthread.php?t=32741&page=12&pp=15&highlight=fields)

It states:

Bug 002 - LW8.2 handles image sequence fields incorrectly

I work for a tv channel. I use LW and it is upgraded to ver 8.2. I use fields all the time so I was puzzled when reading this thread and people stating that 8.2 will not render out fields. I did some tests and everything seems to be ok. I then investigated the bug reports and realized the problem is not with LW rendering frames but with the image editor not correctly handling interlaced frames.

UnCommonGrafx
04-23-2005, 10:11 PM
DIng ding ding!

Rich has it. IF you are using videoclips, what I've said applies. IF not, others advice applies.

It's all good; you just have to know what you want and need.

dgon64
04-24-2005, 12:20 AM
Yes, sorry for the misstatement ,you're correct-the exact nature of the problem is how it "...handles image sequence fields incorrectly". Just thought it was simpler to say to the original query that it was 'broke' in 8.2 than confuse him with technical details. Of course this isn't a problem for a resourceful community like this one as evidenced by everyone's suggestions how they handle this situation -only wanted to remind pilkiwilky that maybe the easiest thing for him to do was wait for 8.3 ( if the other suggestions don't work for him ) since this particular bug is supposed to be fixed in this update. Gui Lo- the contradictions that confuse you could be that you don't always need field rendering-it depends on your particular needs (apples to apples-yes )-but when you're asked to provide-then as always it's best to cover your ***** by doing as suggested-try some test renders and see what works for the client. Nothing beats a good look!

LW_Will
04-24-2005, 06:46 AM
Guys, couldn't he just take the 30 frames into After Effects or DFX+ and do a "reverse telecine" and get interlaced 60 field (60 FIELDS = 30 FRAMES) video?

I heard something about reverse telecine on the DV Guys podcast this week, was wondering why anyone would need that. Now, I understand... :)

Looking to someone to tell me I'm wrong.

Will

Lukesutherland
04-24-2005, 07:36 AM
This thread sure has gone on a few tangents...

I think mainly due to the interpretation on the initial posters question - some people thought he was asking how to handle interlaced video that has been used as a texture within a scene - and others, like myself interpreted the question as how do I render with fields - hence the different answers hehe -


LW - Will - whenever I need to de-interlace footage I use a photoshop action / filter /video / deinterlace (interpolation) - I always work in frames (not avi's or quicktimes) so its a batch thing and no hassle.

I always do this process before my final render if my final destination is film - even if its going to digibeta (then to film) which we sometimes do for cinema commercials.

Within AE there isn't an effective way that I know of without using 3rd party plugins - Magic Bullet I have heard does this really well - but I don't have it...and it's out of our studios budget (too many other things would come first...)

dgon64
04-24-2005, 08:31 AM
Actually I don't mind the tangents-I could always learn something new from the different workflows being posted-but the original post asked a specific question about 60i video which was being recommended by the t.v. station to pilkiwilky for his animation. I tried to give him a basic answer to this particular question but as you can see by the posts maybe there is no simple response because it does come down to- how do you render with fields? Understanding the concept is the first step into making this simple decision and I hope my feeble attempt at explanation hasn't confused the situation even more- but if you have to render in fields then it can't hurt to dispense all of your great suggestions. Thanks for the back-up.

pilkiwilky
04-26-2005, 08:37 AM
WOW, what the hell did I start here?

OK so - I think my answer is... If I am using FPRIME which is a full frame renderer, I should create a PS action to interlace each frame into 2 files - one upper field and one lower, then create a image sequence and give that image sequence to the TV station with 60 images per second? Am I correct. I am ever so grateful for the wealth of knowledge here.

Lukesutherland
04-26-2005, 09:58 AM
Hi Pilky :)
I dont have / use F-prime, but if it only outputs frames then adding fields in that method won't help I am afraid - maybe try a little motion blur (?) - fields help to make motion appear smoother.

How do you get the images from your PC to the station?

pilkiwilky
04-26-2005, 10:06 AM
CD or DVD in an image sequence or Quicktime movie.

So I should not use FPRIME and render fields then use PS?

Would you give me a step by step game plan of how you do this Please?

jds580s
04-26-2005, 10:17 AM
There is a lot of good info here I may repeat some of it but hopefully in clarification not in confusion.

NTSC and PAL both use fields, but there is nothing 'wrong' with displaying image information from the same frame for both the Upper and Lower field. It all has to do with what the desired look is.

Displaying progressive footage as though it has fields makes the motion a little more choppy, the only way to really describe it is that it looks progressive. If the source has fields it looks very smooth sometimes people refer to it as a liquid like movement.

Yes film that is broadcast is from a progressive source but if you freeze frame it and look two out of every three frames will appear to be interlaced due to telecine also called 3 to 2 pulldown. This isn't to add fields to a progressive source though, it's to convert the 24 frames per second footage to 29.97 (for NTSC)

3 to 2 source footage broadcast tends to have a slight stutter effect because there are some frames that are in 3 fields which repeats either the upper or lower field twice. Many people would say "oh that has a film look to it" If a film look is what you or a client wants, this is a great way to reduce render time by about 20% just work and render in 24fps, then in your compositor/editor apply 3:2 pulldown which will split your frames into fields and get you to 29.97.

With FPrime the only current way to get fields is to render 60fps, this will take twice as long as a normal render, and you will be throwing away half the resolution when you output.

With Lightwaves render you just need to use enable fields (or choose to render progressive). If you render from Lightwave with the incorrect field order, it doesn't require a re-render, you can change field order in many editing & compositing apps. It will drop the first field and last field in a sequence so the clip will appear to be one frame shorter than the original.

I personally tend to work progressive. When I run into something that is moving quickly across the screen I'll use fields to smooth it out.

jds580s
04-26-2005, 10:30 AM
OK so - I think my answer is... If I am using FPRIME which is a full frame renderer, I should create a PS action to interlace each frame into 2 files - one upper field and one lower, then create a image sequence and give that image sequence to the TV station with 60 images per second? Am I correct. I am ever so grateful for the wealth of knowledge here.

If your image files contain field information you won't need to provide 60 image files per second, only 30. (Because the other 30 are contained as every other line in each image.


So I should not use FPRIME and render fields then use PS?

Would you give me a step by step game plan of how you do this Please?

You can use FPrime if you want to render 60 frames per second and then us a Photoshop action or After Effects or what have you to convert to fields. If you use Lightwave just render with fields enabled and give the files to the station.

Here is my step by step for fields:
1. Create in LW working at 30fps
2. Render with Lightwave with fields turned on
3. Import into After Effects and interpret with fields
4. Do any post work
5. Output from AE with Fields

with FPrime
1. Work in LW at 60fps
2. Render with FPrime
3. Import into After Effects with a frame rate of 60fps (or batch process with Photoshop)
4. Put the 60fps footage into a 30fps comp
5. Output with fields

Elmar Moelzer
04-26-2005, 12:00 PM
Well, I always try to persuade my clients to use 25p instead of 50i (I am in PAL- land :) ).
That way you get a nice film- look.
They also get it cheaper that way (less rendertime and easier post).
If you are planning to use a lot of effects like imagefilters in your scene you should not use LWs fields- option for rendering, but render to 60 FPS and do the interlacing in post (as has been mentioned before), or you can use the filters of your post- app instead of LWs own.
Many imagefilters have problems with field- rendering (e.g. the glow- effect), which is kinda logical if you think about it and there is not that much one can do about it.
IMHO fields add all kinds of problems to production and I am really wondering why they chose to have 50 and 60 fields/sec again for the HDTV- "standard". I guess they wanted to save bandwidth.
Personally I would have gone with 24p, 48p and 48i for all countries.
Would make working with 35mm footage, telecine and reverse telecine- work a lot easier too.
Well maybe when they do the next "standard".
My favorite sloagan:
Fields are evil!
;)
CU
Elmar

dwburman
04-26-2005, 12:07 PM
I've had a lot trouble with fields in the past especially when dealing with footage from different sources and in different apps. This is especially confusing when the different apps use different terminology i.e. Upper/Lower vs. Even/Odd.

I did some tests using Lightwave, After Effects, a couple of different formats in Final Cut Pro (uncompressed (720x486) and DVCPRO50 (720x480) through an AJA IO). and the Media 100 editor (720x486).

At 720x486 I need to use Odd fields in LW and Lower Fields in AE for Final Cut Pro and also Media 100

At 720x480 I need to use Odd fields in LW and Lower Fields in AE for Final Cut Pro but I need to render LW=Even and AE=Upper for the Media 100 (720x486)

The annoying thing was that whatever field order I threw at iDVD or DVD Studio Pro it worked fine which is good except that the whole catalyst for the tests was a video project that we put on DVD and the fields were reversed.

-------------------

Would it be possible to pilly to render at 720x240 60fps and use some software to combine them back to 720x480 60i? Just a hypothetical thought to save on render time. I haven't tried this. Some how I don't think the LW camera works that way :)

jds580s
04-26-2005, 12:29 PM
I've had a lot trouble with fields in the past especially when dealing with footage from different sources and in different apps. This is especially confusing when the different apps use different terminology i.e. Upper/Lower vs. Even/Odd.

It gets even more confusing when you start wondering which comes first odd or even? It depends on if line one is counted as zero or one :) Some software does it one way while, another package can refer to it differently, thats why it is almost standard now to refer to them as upper and lower. I wish lightwave would adopt this to help smooth the process


I did some tests using Lightwave, After Effects, a couple of different formats in Final Cut Pro (uncompressed (720x486) and DVCPRO50 (720x480) through an AJA IO). and the Media 100 editor (720x486).

At 720x486 I need to use Odd fields in LW and Lower Fields in AE for Final Cut Pro and also Media 100

At 720x480 I need to use Odd fields in LW and Lower Fields in AE for Final Cut Pro but I need to render LW=Even and AE=Upper for the Media 100 (720x486)

There is a fairly simple explanation here. Imagine your 486 lines of resolution that is playing lower field first
now to make that 480 lines you need to crop off 6
usually people would crop 3 from the top and 3 from the bottom, the problem is you just flipped your field order. To preserv field order you need to crop only even numbers
I do 2 from the top and 4 from the bottom (or the other way around) then your fields won't reverse.


Would it be possible to pilly to render at 720x240 60fps and use some software to combine them back to 720x480 60i? Just a hypothetical thought to save on render time. I haven't tried this. Some how I don't think the LW camera works that way :)

No unfortunately it won't because a field represents a difference temporally and spacially. If you tried your whole scene would vibrate up and down one pixel every 60th of a second.
You could combat that by looking at the verticle field of view of the LW camera and moving it 1/480th or 1/486th for D1 up and down to simulate the offset in fields, but then if you used motion blur it would look bad, not to mention any effects in post would be a nightmare

Justin