Mud

ROCKMORE

ROCKMORE

Veteran
What actually is mud translated into real technical language?

Is it caused by hardware, software or both?

What situations will cause the worst problems, fast movement, soft or contrasty lighting?

What are the situations when it will never appear in a frame?

Is the GH1 the only mud-cam or is it just getting the worst mud?
 
"mud" is when the amount of detail exceeds the codec's ability to deal with it, so things get mushy.

It's a hardware limitation based on the type of compression they chose to use.

The worst of it happens when you have extreme amounts of detail, and then combine that with motion. So shooting a forest, with billions of leaves and grass everywhere, and compounding that with some sun peeking through so there's high contrast detail everywhere, and then moving the camera around -- that's about the worst case scenario for getting mud footage.

It won't appear in the frame if you manage the circumstances to minimize the amount of detail that overwhelms the codec. Your standard interview shot with shallow depth of field, for example, is a perfect case of where the codec will perform superbly.

Or stick to 720p mode; 720p mode seems to be much more robust.

All HDV cameras are subject to mud, especially the earliest-generation Sony and JVC HDV cams, and basically any camera with a long-GoP codec with insufficient bandwidth can have it. The GH1 has perhaps the easiest-triggerable mud of any long-GoP camera I've worked with.

But if you take advantage of the shallow-DOF capabilities, you'll greatly minimize the danger of getting hit with a muddy shot.
 
As far as how often you'll run into it if you're a little bit aware of it...I just shot over the course of 6 days on a sailboat at sea with the kit lens. So far, the only mud I can find was a shot where about a dozen dolphins were moving very quickly and playing in our bow wake. The boat (in other words, the camera) was moving pretty heavily, the dolphins were moving and breaking up the water, which was also moving. This caused some problems although out of ten minutes or so I got plenty of useable stuff.

No where else did the boat's motion give me any trouble. I also had an HFS100 with me which did not break-up at any point, but also doesn't quite have the 'look' of the GH1. Showing raw footage to the crew after the trip stunned them, as it looks like scenes from a movie.
 
Barry_Green said:
"mud" is when the amount of detail exceeds the codec's ability to deal with it, so things get mushy.


The worst of it happens when you have extreme amounts of detail, and then combine that with motion. So shooting a forest, with billions of leaves and grass everywhere, and compounding that with some sun peeking through so there's high contrast detail everywhere, and then moving the camera around -- that's about the worst case scenario for getting mud footage.


Or stick to 720p mode; 720p mode seems to be much more robust.

But if you take advantage of the shallow-DOF capabilities, you'll greatly minimize the danger of getting hit with a muddy shot.
Click to expand...

So it's actually pretty easy to avoid with good planning. If a shot has a lot of detail such as a city scene with a lot of buildings, how much movement can you get away with. Any? I usually shoot with a small portable jib on a dolly so my goal is always smooth and steady camera work.
 
A city scene won't have a tenth the amount of detail that the forest scene has. I bet you could execute smooth cinematic moves mud-free, but I haven't shot a crane/dolly type of shot with a GH1. But I bet it'd be fine.
 
I just finished up on a promo for a Salsa Festival (in the Screening Section) and I thought I got away with very little mud. In fact when I frame by framed some of it I saw there was some in places I hadn't noticed before.

Which goes to say that if you look hard you will find it. But if you are just watching a finished piece you really don't notice it.
 
editman said:
I only noticed mud in 720p when having the shutter high. When shooting in 1/50s it's not an issue.
Click to expand...

That's a great point I've been wondering about. Many of the shots that seem to be causing the most trouble are flash pans for effect. All those can be shot as individual elements, cut into place in post later, defocused, speed ramped etc. So if I'm correct you can shoot a series of quick blurry pans at a slower frame rate and even throw them slightly out of focus to soften the image and have a bin full of mud free effects if you need them later?
 
jshaw300 said:
I just finished up on a promo for a Salsa Festival (in the Screening Section) and I thought I got away with very little mud. In fact when I frame by framed some of it I saw there was some in places I hadn't noticed before.

Which goes to say that if you look hard you will find it. But if you are just watching a finished piece you really don't notice it.
Click to expand...

Do you remember what were you doing with the camera when the mud appeared in those shots? 720P 1080P? Was the shutter speed 50th/sec 60th/sec or faster? Was the camera moving a lot or the Salsa dancers?
 
ROCKMORE said:
That's a great point I've been wondering about. Many of the shots that seem to be causing the most trouble are flash pans for effect. All those can be shot as individual elements, cut into place in post later, defocused, speed ramped etc. So if I'm correct you can shoot a series of quick blurry pans at a slower frame rate and even throw them slightly out of focus to soften the image and have a bin full of mud free effects if you need them later?
Click to expand...

For 720p you should always aim for 1/50s or 1/60s to get the right amount of motion blur. This helps the camera to work at it's best and to minimize artefacts.
 
In 720p you must NEVER use 1/50 in the USA model!

1/50 is appropriate for the PAL version, but not for the NTSC version.

If you use 1/50 in the USA version, it will drop your entire footage into becoming 720/30p!
 
Barry_Green said:
In 720p you must NEVER use 1/50 in the USA model!

1/50 is appropriate for the PAL version, but not for the NTSC version.

If you use 1/50 in the USA version, it will drop your entire footage into becoming 720/30p!
Click to expand...

I'm in a Pal country which brings up another question I know is not directly connected here, but I've posted many threads on the subject and never gotten any definitive answer to date.
When shooting a project to be exported to both NTSC and PAL markets, is it better to shoot with an NTSC GH1 or a PAL GH1?
I decided to post the question on another thread.

http://www.dvxuser.com/V6/showthread.php?t=190079
 
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editman said:
I meant 1/50 for PAL and 1/60 for NTSC. Sorry for not differentiate that.
Click to expand...

That's Ok.

I would be interested in a few other challenges for the GH1 sensor.

Does the camera perform better in terms of "Mud" artifacts, with softer focus information presented to the sensor? In other words, if you defocused the camera giving the sensor less detail, and did a quick pan, would it translate the image into a nice creamy soft blur, or would it make up new artifacts to try to decide what it thinks is really there?
(Barry's aliasing explained)

1080p / 720p What would be the difference in the effect translation to the sensor?
 
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I would say the 1080 mode is more sensitive and works great for shoots on a tripod. Everything else go for the 720 which is really excellent on the GH1.

Mud only seams to appear in bright light in combination with lots of details. So with softer focus there is less detail and it should have a higher chance to avoid muding.
 
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