deinterlaced output is not deinterlaced

Thanks for the detailed description. Overall, pretty consistent with what I've found. Although I'm not sure if iMovie09 is broken or Apple has intentionally made it that way. :-/

Steve Mullen wrote:
Export as Upper 1280 AS P -- both odd and even lines are visible on still.

Are you sure you are seeing both fields on 720p output from iM08? If so, when there is motion you should see either that ugly mouth tooth (which we never see with iM08) or ghosting such as this.

I did the same test I did for iM08 to verify single field processing.

Alternating blue (top) and red (bottom) stripes that will each represent fields.

Exported 1920x1080 image as AIC 1080i movie.


Turning on single field red field and turns everything blue. (Effective vertical resolution 540)


Deinterlacing it makes it purple, where blue and red were blended.


720p output from iMovie09.

Two pixel high stripes we are familiar with. Makes 720p from 1080 60i source useless, except for 1080 30p.

540p output from iMovie09.

Red field is dropped.

720p output from iMovie08.

Red field is dropped. iMovie08 makes 1080i ->540p-> 720p.
This is much better and quite usable than iMovie09's 720p output, but you don't get to see both fields in 720p output from iM08.

Message was edited by: Euisung Lee

Very nice test!

I see ugly mice teeth on 720p output. I can't think of any advantage to iM09 de-interlacing in the way that it does.

But, it doesn't matter because you have shown iM08's de-interlace is really crude. So even with 08 one should use JES for adaptive de-interlacing.

When you say "single field" I think you mean both field's woven into 1 "frame" since there are no fields with progressive video.

How did you make such a nice test pattern?

Steve Mullen wrote:
I see ugly mice teeth on 720p output. I can't think of any advantage to iM09 de-interlacing in the way that it does.

The only case would be 1080 30p footage. But not much an advantage for majority of us who don't have or shoot 30p HDV or AVCHD.

But, it doesn't matter because you have shown iM08's de-interlace is really crude. So even with 08 one should use JES for adaptive de-interlacing.

Right. Using JES' adaptive deinterlacing for 720p conversion would be much better (1080i ->1080p ->720p). But I think iM08's method of dropping one frame (1080i -> 540p -> 720p) yields pretty nice result.

When you say "single field" I think you mean both field's woven into 1 "frame" since there are no fields with progressive video.

Although iMovie09 seems to ignore interlacing flag of 1080i source and treats two fields as one progressive frame, I think it knows it's dealing with interlaced video. And it does acknowledge it and discards lower field when user sets output size to 960x540 or smaller. (hence all blue frame).

How did you make such a nice test pattern?

Pattern was made in photoshop. I opened the image in QT player and export it as AIC movie with interlacing on.

"Although iMovie09 seems to ignore interlacing flag of 1080i source and treats two fields as one progressive frame, I think it knows it's dealing with interlaced video. And it does acknowledge it and discards lower field when user sets output size to 960x540 or smaller."

This tiny point is the only thing we disagree on.

I don't think iM keeps track of the "kind" of video. I think it only knows the frame-size and treats all frames as progressive -- even when with 1080i, it's not.

In my view, DV has one field dropped when the captured DV is read from its file. When interlace output is required, the frame is line-doubled with the EVEN field output first. Quality is lost.

Here's why I think there is no flag. If there were a flag, there would be no reason not to have it be: Odd, None, and Even. And, with such a flag, no excuse for iM not to process SD the way it does HD. Then, during export, the flag would be used to govern HOW the re-interlace should be done. This would mean iM would offer great quality DV because the Even flag would tell it how to re-interlace DV as Even field first.

When interlace export is required, if the frame has 540- or 1080-lines ALL lines are used -- otherwise iM line-doubles (240 to 480) half the lines in the 480-line frame. In either case, the frame is then re-interlaced. With 1080- or 540-lines, the Odd field will be dominant -- otherwise the Even field will be dominant.

1) When progressive export is required, if the frame has 1080-lines iM08 drops half the lines (1080 to 540) -- otherewise if 540-lines, all line are used -- otherwise half the lines in the frame (480/576) are used. In all cases, the result is re-scaled if necessary.

2) When progressive export is required, if the frame has 540- or 1080-lines iM09 uses ALL lines -- otherwise half the lines in the frame (480/576) are used. The result is re-scaled if necessary.

The advantage of iM09 is that it allows the user to request DEINTERLACE and have iM09 output 1080-lines from 1080p. But, this is an error! If I am editing 1080p, I should be smart enough to not request a DEINTERLACE because I should be smart enough to know I've already got progressive video. This is an iM09 bug that needs fixing.

Steve Mullen wrote:
If there were a flag, there would be no reason not to have it be

You may be underestimating how strategically cunning Apple could be 😉

I think iMovie has completely different way of dealing with DV vs other formats. iM08 and iM09 simply discards one field of DV and enforce progressive mode in all cases. For 1080i AIC movies its tactic is a lot more convoluted and I don't think we need to make connection between how iM treats DV source and AIC source.

2) When progressive export is required, if the frame has 540- or 1080-lines iM09 uses ALL lines

Here's why I think iM09 is still aware of the flag. Had it been otherwise, it should have used all lines ,as you pointed out, and my 540p output test should've been purple, because iMovie would simply scale it down 50% and blue/red fields would've been blended to be one pixel high purple.


Instead, it is all blue, which means the even (red) field was dropped. For some reason for anything smaller than 960x540 iMovie drops the lowerfield of 1080i source.


I chose an arbitrary scale of 550x230 and I see all blue. Again, lower (red) field is dropped.

To be more certain, I made another blue-red stripe *movie without interlace flag*.

As you see 'deinterlace' has no effect on a progressive movie. No flag here.


This is how quicktime attempts to drop field when there is no field. I think QT simply scales movie down to 50% and blows it back to 100%.

I exported this progressive stripe movie to 960x540 from iMovie09, and NOW it shows what iMovie would do if it sees no flag.

Blended purple image.

So I still think iM09 is aware of the interlace flag, but purposefully treats 60i in this manner. I wish that iMovie would use ALL LINEs for 1080 and 540 only, because 50% scale down is the only thing makes sense for interlaced video. For anything other than 100% and 50% scale it should deinterlace the source or at least drop one field so that you won't get ugly artifact of scaled interlaced video.

The advantage of iM09 is that it allows the user to request DEINTERLACE and have iM09 output 1080-lines from 1080p.

I'm not sure what you mean. Could you elaborate a little more?

Bonus - This is what happens when I drag the corner to scale the stripe quicktime movie with quicktime player.




And much 'thank you' to Sony who insisted on 'interlaced format' for HD video. 😉

Message was edited by: Euisung Lee

Hi All,

Just a quick question, I have a Panasonic SD9 that shoots 1080/50i OR 1080/25p, The destination for my movies will be SD DVD's (watched on LCD & plasma screens) and Apple TV (H.264 720/24p).

My question is due to all the de-interlacing problems mentioned on this post should I just shoot in the 25p mode? 25p mode looks fantastic converted to H.264 720/24p on the Apple TV and also looks fine on DVD from iDVD.

What are the benefits of shooting 50i, I'm right in thinking that both 50i & 25p are only 25 fps aren't I? Or does 50i shoot 50 fps?

Many thanks for help with this.

Dave

David Day wrote:
What are the benefits of shooting 50i, I'm right in thinking that both 50i & 25p are only 25 fps aren't I? Or does 50i shoot 50 fps?

Advantage of 50i and 60i is higher temporal resolution. Although technically they are 25 and 30fps, they render motion in 50 and 60Hz, giving them more fluid video look. I personally like cinema's 24fps look so I don't miss fluid motion much, but everyone has different preferences.

If you want to shoot 25p but want more fluid feel then set your shutter speed to 25. This increases motion blur and although it doesn't have higher temporal resolution it creates the illusion of it.

That's great, many thanks for that. I'll shoot 25p with a shutter speed of 1/25 and see how it looks.

Thanks again.

I've had a read through this thread but I'm unsure as to if there is a workaround to export 1080/50i from iMovie 09 to 720/p?

Is there a way we can do it until Apple fixes this?

Dave

One of the workaround is to export as 1080 50i and deinterlace / resize with JES deinterlacer. This gives you the best result anyway, because iMovie is like to simply drop one field to export clean 720p even if Apple 'fixes' the issue.

Just out of curiosity, has anyone talked to Apple about this issue? Apple Support or a Genius in the Apple Store?

Just wondering if there is any sort of official stance on this from Apple...

I just noticed this post!

"I did this same thing, David, with the same results, burned a DVD with Toast 10 using the Blu-Ray Video option. That's good, but what I really want to do is move my content to a WD TV but I can't -- because until I make the disk via Toast the shutter effect is there."

I am planning on using a WD Media Player.

Are you saying that if you import 1920x1080 and export as UPPER 1080i using AIC -- and watch it on your computer the video has combing but when you make a BD and watch on an HDTV it does not?

If so, then that is correct.

When you export for the WD Player -- I assume you are using H.264/AVC. Are you using 1080i60, 1080p30, or 720p30?

If you want 720p30 you must export 1080i60 UPPER and use JES.

I have no idea if the WD accepts 1080i60 OR if the Apple H.264/AVC can really carry interlace.

Not sure about 1080p30.

I seem to remember the limit for 1920x1080 is 24p.

Message was edited by: Steve Mullen

Yes, in San Jose, California. The guy had no clue...

http://media.macworld.com/media/podcast/mwpodcast153.mp3

This Macworld podcast reviews iPhoto and iMovie 09. iMovie reviewer mentions interlace line problem and he claims that he asked apple about it and apple was looking into it. I didn't listen to the podcast carefully so I'm not sure if he was saying the same problem we are discussing here. BTW, I submitted a bug report and feature request to apple feedback page, and I'm sure many others did the same.