deinterlaced output is not deinterlaced

Steve Mullen wrote:
1) The top 1080i -- if not all of the current 1080i -- camcorders have such good optical stabilization systems you don't really need to more in post.

I think that's a bit of over simplification. No stabilization - digital, optical, or post - can replace the real camera mass. Most of bad home video shake comes from lack camera weight and careless handling by users. OIC can help eliminate high frequency shake but it doesn't give be stabilized look of heavier camera+careful handling. Post stabilization can help a little better sometimes. If you are lucky it successfully makes a handheld camera look more like steady cam, with the price of resolution loss and other anomalies like motion blur burst and incurable CMOS jello. So I think stabilization is still very handy for many home videos, especially those shot carefully within constraint of the physics of lightweight object. (less for CMOS cams but that's another topic)

2) I have no idea how 24p with pull-up to 60i will be handled. My advice is just say NO to 24p when 30p gives the same look and has no issues.

It is generally wise to avoid 24p unless you want specifically the film look, however 30p won't give you the same look.

iMovie pulls up 24p (23.98) movies to 30 (29.97) in NTSC project and 25p in PAL project by adding dummy frames. When exported to 23.98 fps iMovie does remove those dummy frames and gives you clean 23.98fps movies with no duplicate dummy frames.

Editing in 23.98 in PAL project (25p) gives you better representation of what the final movie will be (only 1 dummy frames for each second, instead of 6 as in NTSC setting) and stabilization calculation works much better for 23.98fps movies in PAL project.

But here is tricky part. Output to 23.98 is only possible when your iMovie setting is in NTSC. Doing so under PAL rounds it up to 24.04 even if you set it to exactly 23.98 or 23.976 in output fps setting.

*So here's what I do with true 23.98 movies.*

*1 Set the iMovie Video Preference to PAL.*
*2 Create a new project (this will stay PAL, even if you switch back to NTSC)*
*3 Do editing /stabilization and all*
*4 Switch iMovie back to NTSC*
*5 Export to Quicktime (with 23.98 fps)*

Staying in NTSC all time gives you similar result except for stabilization.

Since few, if any, iM09 users will be converting to 720p60 -- I'm simply skipping any reference to this option. The only real question is: is interlaced video output with reasonably (given iM09's cost) of acceptable quality.

1) no one would expect combing on the edges of moving transition. Combing, a sign that interlace video retains its interlace, should only appear on rapidly moving objects in the VIDEO.

2) no one would expect combing on scrolling titles. Combing, a sign that interlace video retains its interlace, should only appear on rapidly moving objects in the VIDEO.

3) Bob de-interlacing does not NEED to change the frame-rate. Every second, 25 or 30 interlace frames are converted to 25 or 30 progressive frames. For EACH frame processed, one field is discarded while one field is line-doubled to recreate the lines that were discarded. This simple process keeps the number of lines and the frame-rate constant while eliminating interlace artifacts. (You might want to read my article on de-interlacing in Broadcast Engineering.)

4) With my sample of interlace video, I reported that " It APPEARS bob de-interlacing is used ..." In other words, neither combing nor field-blend blue were visible. I'm well aware that other samples showed combing. And, it's possible other samples might show blur. Unless one is willing to spend the time to test many samples with various amounts of zoom -- we'll likely not know exactly what iM09 is doing internally.

4) This thread is NOT about Stabilization. Look at its title, It is about ONE specific issue -- the fact iM09 can't correctly deinterlace to 720p30 for the internet.

Bottom-line -- it's not that iM09 "doesn't understand interlace." Rather, two decisions were made by Apple:

1) For DV, video is bob deinterlaced to eliminate any possibility of damage from interlace artifacts. Of course, this has a big downside -- loss of 50% of DV's vertical resolution.

2) For 1080i, weave deinterlacing is employed. This preserves full vertical resolution when exported using the UPPER 1080i option. However, depending on the AMOUNT of scaling, interlace may cause unwanted artifacts.

From my tests, typical PIP sizes will not be damaged because once the size falls to 540-lines or less, iM09 MAY automatically use only the odd lines. So that's not a real worry.

Likewise, Crop will not be a problem because there's no reason to crop 1080i video as it is the largest frame-size one will be outputting.

So that leaves Stabilization. In this case, it's a simple trade-off. Which looks better -- your video unstabilized or stabilized? The user is free to choose.

So NONE of these issues are "bugs." They are the logical outcome of the fundamental design decisions made when Apple decided to eliminate FX rendering. There is only one bug, which it what this thread is about -- why is progressive export broken. But, even this is a non-issue since progressive output in iM08 was not of the highest quality. Therefore, even with iM08 one should have exported as interlaced and then used JES or MPEGstreamclip to adaptively deinterlace.

Where to begin...?

I've learned a lot from this thread, circuitous though it is. Thanks to all.

My Canon HV20 (miniDV) can do 1080 60i and 1080 24pf (or is it fp?). Towards the end of this thread, which brings Safari to its knees 🙂 it sounded as though 24 might be the way to go, using JES Reverse Telecine after import into iM09. It puts out a nice HD file if one make the right selections - sheesh.

But now, 30p is touted. I would agree with this and if I had an HV30, I guess I'd set it to 30p - no pull-down baloney and iM handles it 'natively'. But I'm stuck with 60i.

I want to zero in on MY STANDARD SETTING for the HV20. 24p is NOT a necessity. QUESTION: should I set 60i, import at maximum size into iM09, and then do the JES Deinterlace (blended)? And THEN edit? Stabilization MIGHT be necessary since I'm 61 years old and can't always have a tripod.

My take is 'Pond' and 'Euising' are in the 30p camp (sorry for pigeon-holing). So is my plan the best I can get? My purposes range from SD DVD to AppleTV 720p (oops - guess I can't start with 30p then, huh).

Forgive the rambling. I think this thread needs to be restarted IMHO...

Rick

Steve Mullen wrote:
1) no one would expect combing on the edges of moving transition. Combing, a sign that interlace video retains its interlace, should only appear on rapidly moving objects in the VIDEO.

You're right that this is getting off topic so I'll stop posting on this particular branch of things now, but before I go - perhaps we have a difference of nomenclature here?

IMHO a moving transition is video, as much as anything else in the frame. If video is 1080i60 then effects transitions and titles +absolutely must+ also work in the interlaced domain unless you want to suffer from undesirable visual artefacts. These are clearly visible in the 1080i60 video grabs in my earlier post, particularly the awful mess of the cube transition. The page curl effect performs pretty badly too. You don't need to convert to 720p to see the problems - it just makes them more obvious.

iMovie does not do interlaced transitions or titles processing because it assumes progressive processing throughout. Thus, iMovie +does not+ understand interlaced video. You later argue (see below) that this is incorrect because you perceive iMovie has having actively chosen to use weave - i.e. "do nothing" - deinterlacing on import, but isn't that the whole point I'm making? Perhaps we're in a sort of violent agreement in some respects! As far as actual editing, composition, titles, effects, transitions and exporting is concerned, the iMovie engine is at present incapable of interlaced processing and the video ingestion front-end has to compensate for this.

2) no one would expect combing on scrolling titles. Combing, a sign that interlace video retains its interlace, should only appear on rapidly moving objects in the VIDEO.

If I render moving titles onto interlaced video then I would most certainly expect combing. Progressive vs interlaced title rendering differences are always immediately visible when viewing broadcast SD TV on an interlace-capable monitor. Interlaced titles scroll smoothly and legibly; progressive titles judder and are usually nigh-on impossible to read as a result (particularly fast moving horizontally scrolling text).

iMovie scrolling titles played on top of interlaced video appear to judder, while motion beneath them moves smoothly. The titles are not updating with the same temporal resolution as the underlying video. The underlying video consists of two fields with a different temporal and spacial meaning, even if iMovie may be turning a blind eye to it by deliberately electing for the "weave" approach, or simply tripping over its feet by not caring about interlace in the first place, which amounts to the same thing.

As you know, the overlaid titles straddle both fields and yet do so for data with identical temporal and spacial meaning. Deinterlacing algorithms (e.g. for playback on inherently progressive mode display devices such as most LCD or plasma TVs) handling the interlaced video on inherently progressive display panels will then break when encountering the progressive sections of the video (the titles). The 720p60 conversion aliasing artefacts are but one example of ways in which subsequent deinterlacing attempts fail.

It may be subtle, but it's still broken!

3) Bob de-interlacing does not NEED to change the frame-rate (...) one field is discarded (...) (You might want to read my article on de-interlacing in Broadcast Engineering.)

I can't find references to bob deinterlacing as anything other than taking both fields, rather than simply discarding one, however I stand (sit?) corrected. But if iMovie turns my video into 1920x540 resolution, then applies further cropping and zooming for stabilisation, the results will be basically hideous. Not only will the resolution be pitiful, but motion judder will be even worse than if I'd just shot in 1080p30, since at least with 1080p30 you might have motion blur from careful shutter speed choice to smooth things over. With field discarding, iMovie will have simply thrown away half the temporal resolution of the clip and no amount of motion blur can fix that.

I suppose in a choice between "break the video completely" and "degrade it to half resolution by discarding fields", I'd have to agree with you and choose the second, but frankly, both suck IMHO! 😀

Bottom-line -- it's not that iM09 "doesn't understand interlace."

We may have to agree to disagree here... 🙂

2) For 1080i, weave deinterlacing is employed. This preserves full vertical resolution when exported using the UPPER 1080i option. However, depending on the AMOUNT of scaling, interlace may cause unwanted artifacts.

Since "Weave deinterlacing is employed" is essentially the same as "do nothing, just treat frames as progressive", you appear to attribute more intelligence to the software than would appear to be warranted. You could be entirely correct, but it's rather academic. If one takes interlaced footage and processes it in iMovie with the intention of treating +the final iMovie output+ as interlaced too, then great care must be taken to avoid titles and transitions which will reveal that internal processing was actually progressive, not interlaced.

Likewise, Crop will not be a problem because there's no reason to crop 1080i video as it is the largest frame-size one will be outputting.

Surely there are many reasons people may choose to crop and up-scale sections of video. Correcting bad framing is probably the most obvious - the majority of people using iMovie are unlikely to be professional camera operators.

So NONE of these issues are "bugs."

Well I disagree, but obviously I respect your opinion. I hope Apple agree with me though, or we're stuck with iMovie screwing up processing of interlaced material and repeated threads about it on these forums ad nausem! 😉

*Closing thoughts...* Whatever happened to "it just works"? Fixes include:

(1) Always apply a more appropriate deinterlacing model when ingesting interlaced footage (even basic field merging would be preferable for people who just want to "import, edit and publish" hassle-free within iMovie)
(2) Give the user the choice of deinterlacing model (probably in iMovie preferences rather than "in your face" at import time)
(3) Implement an interlaced processing engine inside iMovie

Option (3) is I would have thought vastly preferable all round. I can't see that it would chew up so much more CPU power that the editing mechanism of iMovie '08/'09 would suddenly become impossible. You'd incur extra function call overheads for increased numbers of rendering calls to title, effects and transition units, but still only have the same number of pixels to process - twice as many temporal instances, but half as many pixels per instance.

Brief post-script: I tried giving iMovie some 1080p60 footage. That is, I used JES Deinterlacer to convert 1080i60 footage to 1080p60.

With the plist file at the default videoFrameRate setting of 30, iMovie simply dropped every even numbered frame from the imported 1080p60 video in the exported data, using ProRes 422 (HQ) in progressive mode with frame rate set to "Current".

With the same export settings but videoFrameRate set to 60, iMovie exported all frames from the imported 1080p60 video. However, scrolling titles and video transitions sadly still only ran at 30 frames per second, that is, they only moved in every other video frame. Well, hey, I guess it's not Final Cut! It's not really surprising that the transitions/titles/etc. don't run at high frame rates.

For those wanting 720p60 H264 footage for e.g. a PS3, note that I still had to export as QuickTime in e.g. AIC or ProRes before using MPEG StreamClip to encode to MP4. Direct MP4 export from iMovie resulted in the same strange doubled frame 30-fps-at-60-fps video I've seen with JES Deinterlacer exports.

Given the storage space and CPU implications of working with 1080p60 on input to iMovie and the possibility of the video size plist file setting not working in future releases, perhaps it's best to stick with the interlaced work-arounds described herein and avoid transitions, titles or other processing mechanisms in iMovie which show problems with such footage.

" (less for CMOS cams but that's another topic)"

Since all the lightweight AVCHD camcorders now use CMOS -- it can't be another story. It is such a major consideration that Apple felt the need to post a warning.

And, while I agree 100% about the inherent problem of lightweight camcorders, the issue isn't simply about "stability." It's about smooth movement.

I've found Stabilize to reject pans so iM09 doesn't really compensate for a camera's light weight.

In short, the only thing Stabilize fixes are the jitters that, as you point out, are what the OIS already minimizes. I use it only for a camera that has no OIS or EIS. Which is why I said it really isn't of great help to those with Canon or Sony camcorders.

Again, bottom line is how iM works is how it works. Other than telling folks to check how their stabilized clips look -- nothing that's posted makes things different. Either you use Stabilization or you don't based upon how clips look.

Either you use iM09 or you don't.

None of this is related to the bug in deinterlcing to 720p30.

PS: deinterlacing to 1080p30 seems not to work either as combing is still visible.

Yeah.. this thread is now a big mindmap branching out to everywhere 😉

30p would indeed serve your need much better, but what's next best thing possible with HV20?
Honestly I think shooting in 60i and importing at 960x540 would be the best for your purpose. You'll be using 540p30 video so no interlace problem there, and it would make decent SD DVD and apple tv movies especially because you don't seem to mind motion rendered at 30 or 24Hz.

If you want 1080 30p movies, you can deinterlace your 60i video in JES with 'adaptive deinterlacing' to keep the picture as sharp on static elements. But then your output to DVD or appleTV will see no benefit as they will both downsize your video to 960x540 or smaller.

If you want best resolution on apple TV then you can shoot HV20 24fps and go through JES to inverse telecine, and export 720p24 movie but I don't think it's worth the hassle to gain slightly higher picture resolution and lower temporal resolution.

In short, if your primary output is for SD DVD and apple TV, and if you don't need 60Hz motion rendering, shooting at 60i and importing movies at large size (960x540) will save you a lot of headache and serve you well, IMHO.

ps- I'm not on 30p camp, but alone in 24p camp 😉

Steve Mullen wrote:
In short, the only thing Stabilize fixes are the jitters that, as you point out, are what the OIS already minimizes.

It seems to me that iMovie stabilization can handle more than what OIC filters out, but again this may be another subjective issue.

Either you use iM09 or you don't.

This I agree. iM09 doesn't seem exactly 'broken' but rather designed to work the way it does now. Of course there are some outstanding issues like 'deinterlace the source video' not working on Export to Quicktime option, but mostly it seems deliberate. Whether this direction serves general public I don't know, but Apple has specific intention of making this iMovie very 1080 30p friendly and not so much for 60i.

What I'd want it is to have an option to flip switches. An advanced preference setting for - 'deinterlace 60i on import', so that you can safely use 60i source in iMovie if you want to trade 60Hz motion with features like stabilization and 720p output.

Euisung Lee wrote:
Yeah.. this thread is now a big mindmap branching out to everywhere 😉

But it's been very interesting. 🙂

What is the solution for exporting existing 60i video via QT?
HD 1920x1080 16:9
-or-
1920x1080 HD

And, what is 1880x1062? This occurs when using HD 1920x1080.

As I posted when this thread started, I just want to export at full HD with my existing 60i footage. I will shoot in 30p going forward. I have no real need to export at full HD today but I figure I will within the next two years as there likely will be an *easy means* to stream it to a 1080p TV.

When I got home I edited the iMovie '09 plist file to allow 60 fps. I deinterlaced an entire event (19.19GB) to 1920x1080@60p (30.19GB) the files get huge just as a warning!

I edited the iMovie event using scale, crop, slow motion, titles, various transitions, even the 3D cube transition, reverse, some video effects and most of the editing went smooth. *A CAUTION: if you want to use slow motion/reverse, iMovie needs to convert the video clip to be slowed down but it will convert the entire clip not just the selected portion of the clip in the timeline.*

I exported at 1920x1080@60p and the video was awesome! I also tried exporting at 1280x720@60p and the results were great as well.

I'm not sure if this is the workflow I have decided on but at least I know I can use all of iMovie's features without fear of the video being destroyed on export. I fortunately have about 1.5TB of available space to mess around with so the space that the 1080p video will take up is not too much of a worry for me.

Is this the best way to use 1080 60i video with iMovie '09? Any suggestions or downfalls of my workflow?

Kevin

fincher wrote:
What is the solution for exporting existing 60i video via QT?
HD 1920x1080 16:9
-or-
1920x1080 HD

And, what is 1880x1062? This occurs when using HD 1920x1080.

Use 1920x1080 HD, which has been called 'upper setting' because sits upper in the menu. HD 1920x1080 16:9 is supposed to only add a flag for aperture setting, which that 1880x1062 is about. It is a kind of a 'safe area' for HDTVs because some video sources especially those from film origin could have noises or some anomalies at the edge of the frame. With that flag quicktime will crop video to 1880x1062 and only show the safe area, but with digital camcorders it's hardly necessary.

And it happened to be broken with the first release of iMovie 09. That lower HD setting should only add a flag for the crop, but instead iMovie shrinks 1920x1080 to 1880x1062, adds flag, and bring back movie to 1920x1080. I'm sure it should be fixed on the next release but nonetheless it makes the setting useless and destructive for 60i videos.

Now that's an interesting finding. iMovie can not only do 24p editing, but 60p as well! Thanks for sharing your result. So you see exactly 60 frames/sec video in iMovie and output quicktime? This is great.

kjgienapp wrote:
*A CAUTION: if you want to use slow motion/reverse, iMovie needs to convert the video clip to be slowed down but it will convert the entire clip not just the selected portion of the clip in the timeline.*

What was your 60p movie's exact fps setting? Was it 59.94 or 60? iMovie may have required conversion before slowmo because it was not 59.94, which is what NTSC is based on. If your movie was 60, try to convert it to 59.94 and see if iMovie still asks you to convert the whole clip.

Is this the best way to use 1080 60i video with iMovie '09? Any suggestions or downfalls of my workflow?

I'd think so. If iMovie plist hack works right all your effects and titles should've been rendered at 60fps, and if you interlace your 60p output movie back to 60i you will get a very smooth 60i movie, including all iMovie-generated elements. This seems to be the ultimate 60i solution. Good thing that I'm not a fan of 60i cuz I don't have 1.5TB of free space! 😉

I believe the video was 59.940 instead of 60. I didn't realize that that could be a problem. When I get home from work I'll edit the plist file to be 59.94 and then try to edit using the slow motion effect. Hopefully it won't need to convert the video. I also didn't check to see the frame rate of the iMovie '09 generated effects/video, I'll do that when I get home.

Why would I want to interlace 60p back to 60i? My main target is SD DVD for now and then HD on Blu-ray or a standard DVD in the future. I also want to have video on the web but at my own server. I'd like to have a SD and HD version.

Also I'm a bit confused as to how 60i becomes 60p. I thought that 60i would de-interlace to 30p. I'm just curious how that works.

"That lower HD setting should only add a flag for the crop, but instead iMovie shrinks 1920x1080 to 1880x1062, adds flag, and bring back movie to 1920x1080.

Now that's an interesting finding. iMovie can not only do 24p editing, but 60p as well! Thanks for sharing your result. So you see exactly 60 frames/sec video in iMovie and output quicktime?"

1) Actually iM09 is working correctly. Anything that processes video is -- with Clean Aperture -- supposed to CROP to 1880x1062, rescale to 1920x1080, and add the CA flag. This cleans the area that may get artifacts. So it can't be "fixed."

2) I've been editing 720p60 with iM08 since day 1. The downside with FullHD is the big load doubling the frame-rate puts on your computer. It is OK with 720p.

3) Does anyone know what iM09 does when it is "converting" video?

-50% -- play each frame twice
-25% -- play each frame 4 times

+200% -- skip every other frame

This is very crude motion control. No field blending, etc.

It's not clear why iM would need to "do" something to every frame BEFORE it changed the frame-rate. Or, why it would need to check every frame.

4) IF iM discards a field from every frame with DV, and the bobs the lost lines, the result is 25p or 30p video. Why then has no one screamed about stuttering video? They only talk about resolution loss. I'm wondering if a field really is discarded. The alternative is frame blending where the fields are mixed together. (This is what iM does when it plays back video on it's monitor.) Blending converts combing to motion blur. The advantage that as motion increases, blur increases. This eliminates the perception of lost temporal-resolution because our eyes see increased blur as an indication of speed. It does, however, result in a loss of picture clarity.

Steve Mullen wrote:
1) Actually iM09 is working correctly. Anything that processes video is -- with Clean Aperture -- supposed to CROP to 1880x1062, rescale to 1920x1080, and add the CA flag. This cleans the area that may get artifacts. So it can't be "fixed."

Clean aperture only adds flag and *shouldn't rescale* video in any way.



This is how clean aperture should work normally. The source video is not touched. No rescaling, just cutting out the edge of the frame. Quicktime Player does it correctly.


(image at x2)
This is how iMovie exports QT with clean aperture. It rescales 1080 ->1062->1080, unnecessarily destroying the interlace fields in the process. This has been discussed and confirmed quite a few times in this thread. This needs fixing.

3) Does anyone know what iM09 does when it is "converting" video?

-50% -- play each frame twice
-25% -- play each frame 4 times

+200% -- skip every other frame

This is very crude motion control. No field blending, etc.

It's not clear why iM would need to "do" something to every frame BEFORE it changed the frame-rate. Or, why it would need to check every frame.

Yes. iM09's slow-fast mo is indeed simple and crude. But somehow iMovie demands source videos to be NTSC compliant for this to work. I first found out about it when a user said that a 24p movie out of Lumix LX3 had to be converted before slowmo. iMovie converted LX3's movie to 29.97 AIC movie to use slowmo. I found out that when I conformed the LX3 movie's fps to 23.98 in Cinema tools, iMovie didn't ask me to convert it. I believe Jon Walker did more tests and found out that certain codec types like h264 or mpeg4 tends to require conversion regardless of fps, and other intraframe codec movies (AIC, Photo JPEG) needed to be converted when their fps was 30 rather than 29.97.

4) IF iM discards a field from every frame with DV, and the bobs the lost lines, the result is 25p or 30p video. Why then has no one screamed about stuttering video?

I think iMovie still drops field for DV down to 25/30p motion resolution. In my opinion 30fps movie with 60Hz shutter speed is still acceptable for most cases.