JUdder motion wiracle

Postmaster

Postmaster

Dark Side of the Camera
I just stumbled over this and want to share it with you guys.

As you all know, there is some problems with jutter/shuttering motion during a pan - especially on European cameras at 25p.
My solution was to shoot 50p - that doesn't cure the problem, but at least covers it.

I received my Samurai and played around with it.
To use the Samurai, you have to set the HDMI output to 50i.
Accidentally it happened that the recording was also in 50i, instead of 25p.

What happened is, that when set to "record 50i" I get the smoothest motion, but without any scan lines.
When I set it to "record 25p" I get the usual jutter while panning.

I have no idea what´s going on yet, but the images at 50i look beautiful.
No scan lines, no jutter, no resolution loss. To me, it´s a miracle, but what do I know.

I finally get the motion, I was used from my HVX200 in glorious super35 - what more can I ask for?

Don´t know of this works with the Ninja also or in combination with the US cameras.
Also have no idea if the HyperdeckShuttle - that I use as a HDMI-SDI converter, till my Atomos piggy-back converter arrives - has anything to do with it.

Frank
 
Last edited:
Frank I don't get this?

My FS100 does 25p like my EX1, like my 5d - it judders

Thats what 25p looks like isn't it?

I think 30p (which I started out with - filming on the 5d) kind of looks best

Personally I find 50p to be smooth, but make me feel Ill

I have also tried 25th shutter (360) on on the FS at 25p but find that leads to obvious smearing in the image

Tell us more ?

S
 
I don´t get it ether, but hell it works.
I´m setting the FS100 to 50i recording and 50i output.
The file I get from the Samuray is not interlaced (doesn't look deinterlaced ether) and has no judder at all.
When I set it to recording 25p I get the same old judder.

morgan_moore said:
Frank I don't get this?

My FS100 does 25p like my EX1, like my 5d - it judders

Thats what 25p looks like isn't it?
Click to expand...

Not really, I never got this from my HVX


Frank
 
As a fairly bizzare aside comment, I heard recently that the BBC wants its HD programmes progressive, but it wants its CREDIT ROLLS in 50i.

But back to the Samurai. The camera is outputting through HDMI as that's the only port it has. HDMI is a chatty interface that negotiates the best possible outcome for each device working together, but that may not make any sense (AJA, I am pointing a finger at you and the inability to do PSF).

Could there be a sort of 50psf that's being transmogrified (frame blended) to 25p in much the same way as the original JVC HD100 attempted to smooth things out in its own interpretation of 720p25? So, the 50i resolves to 50p that gets frame blended to 25psf?

Just guessing here, and immediately making room in the kit bag for a Samurai.
 
Sounds totally possible to me.

Keep in mind, that the Samuray is SDI only (you need one of the Atomos converters) and can do some pulldown VooDoo ,
that the Ninja can´t perform.

That´s (and DNXHD) the reason I bought it, cause it can pulldown 24p (when we Europeans finally get the FS100 update).

I always suspected the FS100 (European version) to do the 25p/50p with some odd trick and not natively, that causes the judder problem.
But what do I know? It works for me - need to do some sanity tests though - just to be sure.
Frank
 
Postmaster said:
Not really, I never got this from my HVX
Click to expand...

I dont understand that. Even film is 'known to judder' just due to the 'refresh rate' of the eye/brain - hence the reason for DOPs using panning tables and the like

(Ive never shot film BTW)

Of course I think rolling shutter is a consideration to judder - I don't know why but I feel that it is - and that many cameras have r/s even if it is not as obvious as DSLR jello vision

The F65 has an optical shutter gate (does it not) - surely not for fun! - maybe you are somehow recreating the effect that that has

S
 
I have no explanation - all I know is, that I got buttersmooth panning (within reasonable speed - 7 seconds rule etc.) from my HVX and I did not get it from my FS100.
Today I got it from the FS100 the first time.

Frank
 
Are you able to post some examples of what you consider to be jutter? I have an NTSC version and I did not experienced anything unexpected with 24p. Is it something only visible on the PAL model?
 
Looks like only the PAL versions are affected - running monitors at 60HZ in a 50HZ country (unless you have a CRT that runs at 50HZ) doesn´t help much ether.

I post something tomorrow.

Frank
 
Indeed one does wonder on the sreen refresh rate effect on the viewing experience

I am not sure one can judge on a 60hz monitor

S
 
Would someone care to post this phenomenon known as judder up? I have not seen anything out of the usual with any of my FS footage and I own a PAL version.
 
That is interesting. Matts on the ball in that the HDMI interface negotiates the best resolution. For the BM shuttle i have to set the video out to 50i also, but the resulting files are (seem to be) 25p.

What does the resulting Samurai quicktime file think it is?
Is it just the samurai QTs that have the smooth motion, i assume the AVCHD files are real 50i so do they show interlace effects?

Like Morgan says i really don't understand what could be going on here, there was a some research a while back about strobing effects in digital cameras and some conclusions were made about the effects of detail circuits emphasising some of the imagery as it panned, but that doesn't seem to be the case here. Is there any chance it's to do with how you're monitoring? For example i have several apple TVs we use around here but they are god awful for frequency switching and i've had no end of issues with encoding and judder. I finally managed to get them working properly after discovering how the sound was multiplexed made a difference. So what i'm saying is that the monitoring side could have influence as well.

cheers
Paul
 
Isn't this completely normal? 50i is basically 50 fields per second. That is twice as fast as 25p. So is 50p. That's why there is judder on 25p and no judder on 50i.

This is normal. If your playback device can display interlaced it will probably do a quick bob-deinterlace and display the 50i as 50p. Are people forgetting that 25p is basically quite juddering as is 24p?
 
The resulting Samurai files are not interlaced, nor deinterlaced.
They come as 25p full frame and have the motion blur you expect at 180deg shutter.
 
So WTF is going on

You shoot 50p,

Getting 50 frames with 100th shutter blur ?

These are then 2 frames at 50% opacity to create a 25p stream or what ?

maybe you are throwing away half of the frames but somehow the frames recorded render in a nicer manner (i.e. rolling shutter is reduced)

This makes some sense.. shoot 360 deg shutter at 50p and bin half the frames then you have 25FPS with 180 shutter look

but if the camera has to speed up the read time (for some reason) then the rolling shutter is less than just shooting 25p/180deg

S
 
As an aside i've discovered that if you set the FS100 to 1080p HDMI then it's actually putting out 1080p50 even when the recording format is 25p, which is why the shuttle (and it sounds like the samurai) won't pick up the signal. This could all change with the next firmware as this is an area they seem to be working on.

Interestingly if you have an external monitor and the internal together and pan you'll see two different motions, the external monitor will show more judder and more rolling shutter (although this has got to be perception though!)

So there's something going on with sony HDMI output and what it is actually outputting...

cheers
Paul
 
Postmaster said:
I have no explanation - all I know is, that I got buttersmooth panning (within reasonable speed - 7 seconds rule etc.) from my HVX and I did not get it from my FS100.
Today I got it from the FS100 the first time.

Frank
Click to expand...

FRANK !! I talk about it before! .. the reason we've got much more noticable jutter / stattering on FS-100 than on your HVX or on FILM is MUCH MORE DETAILS AND RESOLUTION compare camcorders and NO ROTARY SHUTTER compare to Film!
... so, if we use FAST lenses and reduse extra-sharpering in FS-100.. and shoot at 30fps - there NO MORE stattering .. ( and on 60/50fps even better, but it's useless )
I belive that 48fps will be the best, but we don't have it - this speed used shoot The Hobbit -->

When you will get NEW FS-100 FIRMWARE - 30fps will be available for you also! :)

Here some explanation By Andy Shipsides from AbelCine about this problem: http://www.hdvideopro.com/technique/miscellaneous-technique/help-desk-did-i-judder.html
He says at the end: " Finally, I suggested shooting 30p, which is personally my preference for many different applications; 30p has less aliasing and doesn't completely lose that cinematic look... "
 
I know Andie´s article and I understand all that very well, but it doesn´t explain why I get super smooth motion when I record on the Samurai.

Frank
 
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