Left to Right Pan - Video jitter

[Matt Davis]

Originally Posted by George Angeludis

upload a sample (of raw footage if you can) so every other can benefit.

This might be a very VERY bad idea of mine, but I'm going to share some footage and some experiments with the community here. This is NOT an advert for my wildlife camera skills (!), but does show 25p and 50p footage in SD and how the encoding can affect the output.

http://www.mdma.tv/interlace/PROG_V_INTERLACE.dmg.zip

It's a 250 MB download of a Mac .dmg file of a PAL DVD. American friends please take note, because an American DVD player that can play PAL is rarer than chickens' dentures.

It's primarily a demonstration of 're-interlacing' from 720p50, but of the four variations, there is one bit that demonstrates significantly more 'stuttery' movement, and it would be great to see if others spot it (IOW, not just me seeing things).

If you do decide to go through the rigmarole of downloading the .dmg and burning a DVD from it, please note that it really needs to be viewed on a consumer display device, not a computer monitor, as you'll need to see the difference between interlaced and progressive video.

But the chickens are cute.

[George Angeludis]

This is not a bad idea but this is how you explain something to others to see.
I don't see how this is a bad idea. Only we PC users we need to convert the .dmg to .iso using Magic ISO.

[Matt Davis]

Originally Posted by George Angeludis

I don't see how this is a bad idea.

It's got some very amateur (embarassing focus) camerawork from me early last year, whilst I was learning how to use the EX1. And we have some very pro cameramen here... Just so long as we're clear that this ain't no showreel!

[George Angeludis]

The only things which comes in my mind is about any connection of jitter with bad focus.
Because if you see rushes left out from future films you can feel the shame for the professional arriflex cameramen. But those things are happening all the time.
Thanks for sharing. I will burn this and watch to my Daewoo desktop DVD at my old 21'' PAL TV.

[George Angeludis]

Use Ultra Iso and from Menu>Tools>Convert the image to .iso.

From the first check on my PC's screen of the .vob files after converting the .dmg to .iso this seems to be a software converter problem. I will follow on this.

[George Angeludis]

I watch the DVD at both interlaced and progressive.
The Image even burned to an SD DVD Looks amazing.
I can't see any problem whatsoever.

[Matt Davis]

Originally Posted by George Angeludis

I can't see any problem whatsoever.

Thank you! I think I may be going mad, but I believe there may be an issue when progressive material gets treated as interlaced at the encoding stage, in that progressive material goes on an interlaced timeline, gets exported and maybe partially deinterlaced? I thought I could see choppier motion on the progressive section of the interlaced movie.

After a couple of hours of scrutiny, all I see is chickens...

[George Angeludis]

I will ask though why progressive material to go on an interlaced timeline?
I am shooting 25p with my small HV30 and as we know this outputs 50i from the firewire.
I can see some jerkiness if I want to because that thing isn't real progressive and it isn't real interlaced.
The truth is we are facing images never seen before.
I mean even from my tiny HV30 the footage looks peculiar.
It isn't film but it doesn't look like video either.
Especially if you shoot like I do with Cinemode and 25p.
Over 10-15 years I haven't seen anything like that.
And we aren't yet in era that we are seeing the full beauty (or else) of those images.

[Shawn Dooling]

Ok thanks for the help guys. Looks like when i play full screen through the clip browser it has the jitter on my 24" Monitor. But looks normal when i play it back in the browser preview screen and it doesn't have the jitter.

i feel better now.

I'll test it through FCP and my more powerful system this week.

thanks for the feedback.

[Matt Davis]

Originally Posted by George Angeludis

I will ask though why progressive material to go on an interlaced timeline?

This DVD was a test, so I included some odd combinations so I could spot mistakes in the future - hence 'interlacing' 25p footage. In theory it shouldn't damage things, but what of the display technology? Will it try to deinterlaced interlaced footage based on progressive source? That's why there are some illogical combinations, and why I think there may be an issue there with some displays.

Originally Posted by George Angeludis

It isn't film but it doesn't look like video either.
Especially if you shoot like I do with Cinemode and 25p.
Over 10-15 years I haven't seen anything like that.
And we aren't yet in era that we are seeing the full beauty (or else) of those images.

It's the low resolution HD look. It's an ungodly combination of broader exposure latitude, no interlacing, wider depth of field and occasional shutter issues. As it extends the realm of the DSR-570 which shoots most of the material in my domain, I quite like it.

But I am considering following in Mr Bloom's footsteps with a 35mm adaptor...

[David Herman]

Sorry to join this discussion after it has cooled, but I googled 25P jitter ex3, as I watched some footage I shot on my newish ex3 on a 32" presentation monitor last night and swallowed my heart when I saw how jittery a slowish follow pan was. I persuaded myself it was because I had steadyshot on and my shoulder brace and tiffenstick combo is almost tripod like in its stability. Now am I understanding correctly that it might be a monitoring equip problem? If so, when will it disappear in the process of editing?

[Alister Chapman]

Lets look at some of the issues here:

Monitors:
Almost all PC monitors run at 60Hz, so feeding a computer monitor with 50i, 25P or 24P will produce strange artifacts as the computer/monitor has to add odd numbers of extra frames to pad the frame rate up to 60Hz. This will be un-predictable and depend on the the individual set up as to how bad this will appear.
Consumer LCD's and Plasma screens are progressive devices, but if you feed them a component signal they may try to de-interlace it. This could add undesired artifacts. I have come across some Plasma screens that run at 30Hz regardless of what is being fed into them, again this causes problems. Also the bigger the screen the worse any judder will look.

The only way to be sure of seeing the image correctly is with a proper high grade HD monitor with HDSDi.

Computers and software:
This is a minefield with different computers handling HD playback differently depending on many factors. One player may work well, while an edit package is not so good and vice versa. I would never trust the motion playback on any computer monitor. The only time I would believe what I am seeing is if using a Decklink or AJA HDSDi card on a properly spec'd Mac or PC feeding a Pro grade HDSDi monitor.

24/25P
There will always be more judder with 24/25P than with 50/60i. The frame refresh rate is half as high. Also if you don't use any shutter on camera moves the image will soften. On the one hand this can reduce the appearance of judder, but it may make the camera movement more obvious. The general advice is to always use a 180 degree shutter (1/50th,1/160th). Shooting at 24/25P means being careful with pans and other camera moves to avoid the speeds that cause judder. This depends on focal length, distance to the subject and depth of field.

Picture Detail:
The higher the resolution of the image the worse any judder will appear as your eyes/brain have more to latch on to in each frame. High detail levels will make the problem worse, monitors with too much aperture correction or detail enhancement (very common on consumer TV's) will only make things worse.

Large Screen Size:
The bigger the screen and the closer you sit to the screen the worse the judder will appear. Just go to and watch an IMAX movie and look at the judder in most of those!

In conclusion there are many reasons why your 24/25P may look wrong. Some may be simply poor monitoring, some may just be the limitations of shooting at a low frame rate. But I have yet to see any evidence of an EX camera producing a progressive image that is any different to any other progressive camera, other than in some cases picture skew. But skew doesn't affect judder and is a whole topic of conversation on it's own.

[David Herman]

Thanks for the detailed reply Alister. Having shot interlaced for too many years, 25p is newish to me. However I did shoot a broadcast doc last year with an XL2 in 25P 50 and it was not problematic. This footage I viewed for the first time at the BBC Bristol on one of their large presentation screens, played out of my hard drive through a macbook pro. It was really dreadful. Hence I am hoping that steady shot was playing a part. I haven't had a chance to shoot again since then and am now heading on holiday so I want to forget about it for two weeks. For me the proof of the pudding has to be screening it on a home telly screen as that is my market. (hopefully)

[Alister Chapman]

Originally Posted by David Herman

This footage I viewed for the first time at the BBC Bristol on one of their large presentation screens, played out of my hard drive through a macbook pro. It was really dreadful.

That's probably the problem. It's the worst case scenario. 25P played back via a computer onto a large screen. The computer will be converting the footage from 25fps to 60fps on the fly. It will be adding 2.4 padding frames for every original frame. It will be nothing to do with steady shot.

[Piotr Wozniacki]

Originally Posted by Alister Chapman

That's probably the problem. It's the worst case scenario. 25P played back via a computer onto a large screen. The computer will be converting the footage from 25fps to 60fps on the fly. It will be adding 2.4 padding frames for every original frame. It will be nothing to do with steady shot.

IMHO, it doesn't need to be that way, Alister. I don't know about nVidia, but my ATI card's driver has settings for PAL (HD)TV output (via DVI->HDMI), where I can set the refresh rate to 50, or 100 Hz.

Using this setting, I can watch my 25p video (both from HDD and BD) without excessive judder, even though my 50" Panasonic (refreshing at 100 Hz) plasma is hanging above my computer post at just 1m from my eyes!