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View Full Version : Attempts to avoid 24p codec breakdown



Ian-T
05-24-2009, 09:02 AM
I have a thought on how to avoid those ugly artifacts when you want to use 24p. From what I have been observing with the codec it seems that the normal motion blur is what causes it to go haywire. Whenever an object is relatively still or slow in motion everything stays in sharp detail.

What if one were to increase the shutter speed while filming 24p so as to keep mostly everything in motion sharp as a tack. Then in post production add motion blur to the same footage. This I believe would avoid the compression ugliness and at the same time give one control over the blur. Sure...it's more work in the end...but I think worth the try.

This is also why I believe 60p looks better in this codec than 24p...because it has more information and the image for slow motion usually is set at a higher shutter speed.

What do you guys think. Kholi or anyone could you give it a try?

Edit: Of course when you do this make doubly sure to keep in camera sharpness completely off. This will wreak havoc on the weak codec.

Ian-T
05-24-2009, 09:08 AM
This is probably the same method folks used to get their DVX footage looking so sharp without having to use something like unsharp mask etc. in post.

Nighthawk
05-24-2009, 04:47 PM
I have a thought on how to avoid those ugly artifacts when you want to use 24p. From what I have been observing with the codec it seems that the normal motion blur is what causes it to go haywire. Whenever an object is relatively still or slow in motion everything stays in sharp detail.

What if one were to increase the shutter speed while filming 24p so as to keep mostly everything in motion sharp as a tack. Then in post production add motion blur to the same footage. This I believe would avoid the compression ugliness and at the same time give one control over the blur. Sure...it's more work in the end...but I think worth the try.

This is also why I believe 60p looks better in this codec than 24p...because it has more information and the image for slow motion usually is set at a higher shutter speed.

What do you guys think. Kholi or anyone could you give it a try?

Edit: Of course when you do this make doubly sure to keep in camera sharpness completely off. This will wreak havoc on the weak codec.

What shutter speeds are you thinking or is it dependent on the level of motion the camera is detecting? The faster and more erratic; increase the speed accordingly? I ask 'cause of some car mount stuff I plan to shoot. Kholi initially recommended 60p for that but his later posts gives some hope for 24p. Your question might be my answer. Thanks.

Ian-T
05-24-2009, 05:16 PM
I was thinking more in terms of a 1/120 shutter speed. It's not too fast to cause a lot of strobing and the image should appear a little more sharp (without any in-cam artificial sharpening). That's also the same shutter speed you would want to use in 60p for smooth playback of slow motion.

I'm just thinking that the blur from panning or quick motion is the cause for the codec to flip out like it does. If we can prevent (or minimize) this blur we might be able to use this as a temporary solution until Panasonic comes out with a fix. Hopefully someone can test this out.

John Caballero
05-24-2009, 08:03 PM
Once we have a camera in our hands we will find out for sure what we can or can't do. Until then.....

dmoreno
05-24-2009, 08:46 PM
In theory, a blurred image (or an image with high motion blur) should be easier to compress due to having less detail. Also the "pixel to pixel" change from one frame to the next should be less when motion blur is present.
I would think it would work the opposite way, the highest the shutter speed during high speed motion the more the codec would break. We will only know till we have the GH1 in our hands.

Kholi
05-25-2009, 01:42 PM
How to break the compression in 1080/24:

A) Aperture/Iris or Shutter Change: Change either in real-time and the compression will studder for a few frames.

B) Shoot a lot of GREEN detail: Dunno why, but heaps of leaves and such this camera doesn't like. It's less an issue when static or telephoto, but wide and panning, you can see it if you look for it.

C) Panning faster than you should with any camera to avoid judder: This'll do it as well in 24P.

Dmoreno has it right for the most part, the lower shutter should actually help more than the higher shutter.

For any of these situations, if you MUST do it in excess and you're worried that it will ruin something shoot 720/60P.

I'm very confident that it just doesn't matter, though. And John is right about having the camera in your hands, but more-so having it in your hands and shooting something worth looking at in the first place.

Camera "tests" will always look more flawed than an actual production. Because there's generally nothing interesting to look at in the first place. =D

John Caballero
05-25-2009, 02:57 PM
If you are shooting a pan with wide angle you wont be looking for shallow DOF mostly. So if you lower the shutter speed and close the lens as much as possible, getting the ISO higher if necessary, you might get a more solid image I would think. Maybe, Kholi? You can pan on wides then get static on medium shots, close-ups etc. Anyway, this is a great learning process for everyone here whose gonna get the cam. Eventually we will all get some very nice shots.

Kholi
05-25-2009, 03:05 PM
If you are shooting a pan with wide angle you wont be looking for shallow DOF mostly. So if you lower the shutter speed and close the lens as much as possible, getting the ISO higher if necessary, you might get a more solid image I would think. Maybe, Kholi? You can pan on wides then get static on medium shots, close-ups etc. Anyway, this is a great learning process for everyone here whose gonna get the cam. Eventually we will all get some very nice shots.


Right. Unless youre doing stylized composition, but otherwise panning on a wide you're probably not trying to do a whip pan nor are you looking to get too much depth.

Will closing the iris down work? I thought so but either way it went I still got compression artifacts.

But trust me when I say that what you guys are seeing probably won't effect you once you start using the camera for actual material. I know a few people that would vouch for that specifically pertaining to the GH-1 and stuff that they've seen that others haven't.

Hehe.

My final advice would be to test when you get the camera, find out what works for you. Then shoot something serious and entertaining. When it's test footage, every frame is scrutinized. When it's serious, the single frames don't really matter.

But yeah, you'll see.

Ian-T
05-25-2009, 03:12 PM
Well...not making any excuses here, but I've seen professional movie trailer's image break down when I paused in certain places of the film. I would have never noticed it had I not paused in the first place. I'm just going to have to learn to adapt to this cam's weakness...like I did for my HV20.