PDA

View Full Version : Converting 60i to 24p. A real world Case Study



Jarred Land
08-23-2005, 12:12 AM
Click Here to Read the Article (http://www.dvxuser.com/articles/60i/)

monte
08-23-2005, 12:34 AM
I've never been rational, I'm finding, but this article wasn't bad. Nice work. Actually I haven't read it yet I just wanted the first post. Well I read some of it. Sorry I'm a douche... per my name...

Okay

Yes, that is nice info - other uses - having good looking slowed down 60i footage without so much information loss. Just imagine how cool that would be. I mean right now it's not horrid, but it's noticable when you compare images.

Good stuff

SPZ
08-23-2005, 12:34 AM
Very well written article. Very informative. It has cleared many doubts I had about deinterlacing! Jarred, these 60i images are from Beta SP or DV?

Anyway, Jarred, can you try posting deinterlacing footage from FCP? Since I work on this platform, I really would like to see how it compares to either vegas or filmmaker...

One more question: You captured the footage in vegas, than exported it to AE, then rendered the footage in 23.97, right? Any generational picture loss in this? Wouldn't Magic Bullet Editors do better, or does this only serve fpr color correction?

Sérgio

Jarred Land
08-23-2005, 12:41 AM
Neither me or Nick use FCP so we cant really output it, but i imagine it would have a similar result.

The footage was not exported to AE from Vegas, the raw footage was input into the various programs and the outputs where brought into vegas where the WMV output was made for each clip. The Stills where before the WMV process.

SPZ
08-23-2005, 12:49 AM
Here's a very dumb question: can you capture video in After Effects? I've only used it with inported footage captured in other applications... And everythime I export the footage back, I feel there's a picture quality loss...

As for the content of the article... You are doing a documentary, right? You must have hours and hours of footage... Are you doing an EDL of everything, or doing a full cut on Vegas, then recapture everything and convert it on After Effects? I do documentary, and I usually see the tapes and make up my own mind while capturing, somethimes ending with lots of junk footage, wich I select during editing... I find that I'm discovering my subjects during the editing process... It's when I have time to think about my own preconceptions and confront it with a certain distance from the events and the subjects itself (i believe i get too closen to the subjects while shooting)

Jarred Land
08-23-2005, 01:10 AM
its a little off topic SPZ, you should ask your questions in the AE forum.
http://www.dvxuser.com/V3/forumdisplay.php?f=31

nickybee
08-23-2005, 01:18 AM
you cannot to my knowledge capture video in after effects.
however whenever we have used after effects in the past on DV projects (I usually use to create comps or title sequences) I export uncompressed AVI's from it and then reimport those into whatever NLE I am using.

There's a storage hit with this method of course - but it's the highest quality way of doing it (otherwise you get generational loss)

That's of course why as Jarred described we went uncompressed with each of the deinterlacing methods (including Vegas) before bringing it back into vegas to take screenshots and to create WMV outputs.

As for how we will end up magic bulletising our documentary.

No we will not recapture everything in AE - we will (probably) finalise our cut in Vegas - and then create trimmed media for all the 29.97 clips - and then magic bullet them each one at a time. Yes it sounds as painful as it's probably going to be. To be honest even pushing it via the Terranex box will involve some step like this anyway. I estimate approximately 20 minutes of our documentary (if that) will need to be treated this way - so that's about 20 hours of render time...not too bad in the long run if you get the pristine quality.

Nick

SPZ
08-23-2005, 01:26 AM
The subject of the Documentary sounds really interesting. Sounds like award winning material there. I really would like to see it! I'm really interested to see if "mercenaries"end up feeling something for their contractors: IE warlords, cause fighters, etc. Is it only for the money? How about ethics? there's a certain romanticism in the concept of Mercenaries- heroes without a cause? So many ways to explore this... Very exciting, indeed!

mvb
08-23-2005, 03:28 PM
The test was good but I found the conclusions wrong. Rather than look at individual frames it is more instructive to step through the videos frame by frame:


1. Vegas method. The shot with the machine gun clearly shows an unacceptable loss in sharpness in the patterns on the ground behind the gun vs. the other two methods. In this case the static part of the scene is in the background, but what if it were the principal focus of the viewer's attention? For this reason alone one should strike out using Vegas, it will blur the static parts of a scene too much.

2. Magic Bullet.

a. In the first shot (the soldier) the twitter on the vehicle edges is clearly worse than the other two methods.

b. In the first shot, look at the motion of the soldier's foot. Stepping through it, you can see that the motion of the foot is long-short-long-short, etc. and it is not moving the same amount per frame. This implies that MB is not blending or morphing two fields together when the optimum sample point is between two fields, rather it is always taking the
2nd field. This results in much less smooth motion that the field blending method used by Maker and Vegas, or for that matter a morphing method such as used by Twixtor.

The only shot where MB has marginally better results is the track past the bridge. It's moving so fast you can't tell MB is not taking even steps. However in an extreme case like this of very rapid motion, the best method is to convert to 30P instead and then slow it down to 24P. All three programs would give better results with this method.

Matt Grunau
08-23-2005, 04:48 PM
Out of curiosity, did anyone try to jut use the 60i method out from After Effects and compare that to Vegas?

nickybee
08-23-2005, 06:59 PM
I don't see what you see re: the twitter on vehicle edges or the motion of the soldier's foot.

Me and Jarred discussed the results we got and we were in agreement on our conclusions - although this is obvious it's worth stating that these are just two opinions. It's possible some people may prefer the softer/smoother versus sharper/more artefacts approach.
If someone really wants to try this test for themselves they can easily do so since both programs have demos available.

The point we were trying to make is what kind of results you get out of the box - and what we thought of them.

With respect to the converting to 30p first - yes we considered that - as we did "tweaking" the settings in Maker 2.2 (for motion estimation) or setting the "de-artefacting" in magic bullet to on....but in the end decided the most useful test is the basic defaults on creation of 24p from 60i.

Nick

gumonstro
08-24-2005, 07:15 AM
Iīve made some tests with MB and DVFilm Maker. The MB results were sharper and with better resolution, but FLICKERING a little. DVFilm Maker had a little lack of resoluion, but the movements were soft. The flickering effect is so annoying that I prefer DVFilm Maker over MB.

Is there any way to fix this MBīs flickering problem? I followed all the steps on MB user manual. My version is 2.0 demo.

I always wanted an answer to this question: how different is a 60i SD footage with MB from a footage shot with a 24p camera? How better is the 24p native?

gritsngumbo
08-24-2005, 08:31 AM
Jarred: You mention that the price of DVFilm is $129, their site shows a price of $145. Did you snag us a DVXUser discount for DVFilm? Thanks.

Barry_Green
08-24-2005, 01:32 PM
I always wanted an answer to this question: how different is a 60i SD footage with MB from a footage shot with a 24p camera? How better is the 24p native?
24P Native footage can hold a full 480 lines of information. 60i footage holds, at max, about 360 lines (due to the de-flicker blending-between fields process). De-interlaced 60i footage holds about 240 lines max.

So at a bare minimum, mathematically, 24P Native will have a 33% resolution edge, and perhaps as much as twice as much res. As a practical matter, smart-deinterlacing lets much of the frame stay untouched when using DVFilm Maker, so you won't see a drop to 240 lines on every shot, just on moving items.

Jeremy Ordan
08-24-2005, 03:13 PM
Great article. It is by reading things like this that we can save a ton of time personally going through trial and error. Simply brilliant. Great job. I just wish you came up with the free solution as the best one. Oh well...

Jarred Land
08-24-2005, 03:16 PM
Great article. It is by reading things like this that we can save a ton of time personally going through trial and error. Simply brilliant. Great job. I just wish you came up with the free solution as the best one. Oh well...

well we try :)

cant do free, but considering dvmaker is relatively free, and includes so much more than just de-interlacing its probably as good as your gonna get.

Im gonna get Nick to post the uncompressed file so you guys can download it and apply whatever tricks you have or software other than mentioned, and i will append the article with your attempts.

gumonstro
08-24-2005, 03:54 PM
Thanks for the answer, Barry.

Anybody could answer my other question:

Is there any way to fix this MBīs flickering problem? I followed all the steps on MB user manual. My version is 2.0 demo.

Loi Banh
08-25-2005, 03:33 PM
Thanks for sharing the results of your test. However, I found the conclusions completely opposite of my testing and further analysis of the images, especially compared to the new kid on the block, Compressor 2.

In my testing, even before Compressor, I found Magic Bullet's 24P conversion pretty awful.

The 2 biggest flaws of Magic Bullet's approach is:

First, it does not do a true interpolation of 60i frames to 24P, but rather takes the nearest frame sample. This causes the strobiness that I, like many, have found to be unacceptable. It is even hard to watch. Even Red Giant (or the Orphanage, take your pick) suggest MB works better with PAL 25fps source. Twixtor and ReTimer, in this respect, do a better job since they do real pixel per pixel tweening. But they have their own problems, which I won't get into too much detail but the main problems are interlace flickering and crossing objects. So for 24P conversion, Magic Bullet is not the first, second or even third choice as a software solution.

Second, Magic Bullet uses a sort of fuzzy-logic interpolator to rebuild missing details between fields. This approach works for very distinctive diagonal lines and curved surfaces, but the search patterning it employs completely fails on textured surfaces, like cobblestones, bushes and other fine detail patterns. When it does fail, the interpolator fails spectacularly creating harsh pin-like spikes or very unacceptable swirly patterns. This is noticeable in the second comparison picture in SCENE 2. For still images, MB does indeed rebuild lost data well. Even the Orphanage suggests you use MB to de-interlace portions of the frame and use traditional de-interlacing on other parts. Great suggestion if you are doing a 3 minute music video, but undoable on a feature length film.

With that being said about Magic Bullet, I believe the best 60i to 24P conversion utility available now is Apple's very own Compressor 2, which is bundled with Final Cut Studio. Compressor 2 uses optical flow technology passed down from Shake to do pixel accurate frame interpolations. In my testing, it does a much better job than Twixtor in that crossing objects do not "wobble" or tear. In cases where Compressor can't do a tween because the areas in the frame change too much, it reverts to frame blending in those selective parts of the image.

On to Compressor 2's de-interlacer. One word. Awesome. In my testing, it produces results equal to and better than Magic Bullet, and without MB's swirly artifacts. It uses what Apple calls "motion compensated" de-interlacing which is similar to motion adaptive, however it uses pixel tracking to identify fields and re-interpolate the image. This results in extraordinarily accurate reconstruction.


Here are some comparisons. I intentionally left out Vegas in this comparison because it uses field-blending which many programs can do.

Scene 1http://www.loibanh.com/dvxuser/scene1.jpgIn the MB panel, you'll notice in the circled areas where MB completely fails. It introduces spiky artifacts that is noticeable not only in the WMV clip, but one can only imagine this on the big screen. DVFilmmaker and Compressor 2 do a better job, in my opinion.


Scene 2http://www.loibanh.com/dvxuser/scene2.jpgMagic Bullet's flaw made loud and clear in this example. Just look at the ground. This, in my opinion, is totally and completely unacceptable. No ands, ifs or buts. It reconstructs the gun very nicely, but even upon closer inspection, certain areas have what appears to be single pixel cut outs, especially near the barrrel crosshairs.

DVFilmmaker has a very standard de-interlacer that merely interpolates the missing data, resulting in a crunchy, half-res look, noticeable in the diagonal lines of the gun.

Only Compressor 2 pulls off the best-looking still, and with 24P optical flow technology, also produces the smoothest 24P of all the clips.


Scene 3http://www.loibanh.com/dvxuser/scene3.jpgMagic Bullet artifacts rears its ugly head again. If you think I hate MB, you're right. I think MB is totally overrated. The only saving grace for MB is their superb de-artifacter, which I still love and use only. All these frames are in the same point in time, but for some reason, MB shows a slightly different frame as you can tell from the position of the bridge pillars. Compressor shows the frame as it is tweened, which is the correct version. The tweening also produces smooth railings even MB can't do. The DVFilmmaker sample show faint interlace lines (circled) so it doesn't completely remove the interlace artifacts. It also uses field-blending which some find objectionable.


Conclusion

As you can see from these samples, there are better alternatives to DVFilmmaker and Magic Bullet. I've found Compressor 2 to be the BEST 24P convertor. It is an undiscovered jewel and not the first place you look when considering 60i to 24P conversion options. It's only available on the Mac, so this limits it viability to PC only users.

So if I had to rank the software choices from quality from 1 to 10, 10 being the best 24P solution, it would be:

10 - Shoot 24P natively.
9 - Apple Compressor 2
6 - Tied between DVFilmmaker and Vegas
3 - Magic Bullet

nickybee
08-25-2005, 07:49 PM
very interesting results...
compressor seems pretty cool - I wonder if someone will step up to the plate and make a better conversion tool for the PC (given that shake "was" on the PC and that boujou can easily handle all the pixel tracking issues with its algorithms I imagine it's not a million miles away for someone to do that)

The artefacts you pointed out with magic bullet however I do not find that obvious - with the exception of one - and that is the second scene. Now that you've pointed it out I see the swirly patterns on the sand aswell - but I don't see how you can rate it so low in comparison to Maker and Vegas alone - their stuff just softens everything.

But hey - each to their own - it is after all an observational issue. - Out of curiosity how fast is Compressor...? I have access to Mac hardware and if it's significantly faster we could just use that for the feature...

Nick

gumonstro
08-28-2005, 10:36 AM
Though I think MBīs 24p conversion is unacceptable, I liked a lot Camp Slaughter, shot with a PD-170 and converted to 24p by MB. I donīt know what settings the director/editor used to avoid the flickering, but it works fine for me. Maybe thereīs a trick to solve this flickering problem. Anyone can give us a tip?

stokestack
10-24-2005, 08:44 PM
I wonder what you guys are referring to as "flickering." I have noticed some strobiness even when deinterlacing 50i footage to 25p with Shake (same logic as Compressor). I wrote it off as possibly a simple case of high shutter speed. Try a slower shutter.

John_Moore
11-12-2005, 12:58 AM
As far as I'm aware, Qumonstro, the in camera sharpening on the VX2000/PD150/PD170 must be turned off in order to avoid strobiness.

KyleProhaska
01-11-2006, 08:32 AM
Instead of using Magic Bullet I have tried out Twixtor3Pro for After Effects and I must say its better than MB. From my own results thats what I have drawn from my own tests. It has way more options for Deinterlacing, Frame Rate Converting, etc. I highly recommend you try both to see for yourself. Deinterlacing 60i to 60p then to 24p is a great thing especially when with 60p you can slow your clip down to almost a quarter of the speed. Try both, then choose.

-Kyle