Pixelation/Compression Problem at DVinfo.net

Tim Clark · May 20th, 2005, 01:11 PM

I'm having a little trouble with some of the images I'm capturing and wondering if anyone can help.

I've got FCP4 and I'm downloading footage into my External Hard drive from my DVX100. I'm not shooting in the progressive 24p mode and all my settings are correct for DV in Final Cut.

I have added some filters, including widescreen and color correction, but when I view my footage in the timeline I can see pixelation in the background colors. The background walls will have pixelated boxes with lighter and darker boxes that will move and swirl about behind the talent in the shot.

I will see this pixelation in the canvas, but I will also see it in the DVD that I burn from DVD Studio Pro. So, I'm sure it's not just "playback" quality.

A computer-geek friend of mine says it's a problem of compression, but I'm not sure where the problem is. I've got all the capture and render folders in the same external drive, all going through FireWire. And all the footage has been properly rendered. I've even tried to desaturate the color so the computer won't try so hard to find the "correct" color on that background.

He suggested that I re-capture the footage and try again, but it's happening in nearly every project I start. Anyone dealt with this?

Glenn Chan · May 20th, 2005, 01:21 PM

Are you using secondary color correction in the 3way CC filter? If so, hit the show mask button and see if you see the pixelation/blockiness there.

The 4:1:1 color smoothing filter may help a little, along with the softness settings in the 3way CC (drag the bottom sliders out so it the limit effect settings look like chopped off pyramids).

2- With no effects, do you see your problem?

Tim Clark · May 20th, 2005, 01:39 PM

I did not use the 3-way corrector, only the basic corrector.

I'll give that a try. Will the color smoothing make the picture any less sharp or more out of focus?

When I turn off the effects, the problem is still there. However, when I look at the original footage in the bin, it is not there. Which is why I was concerned about some sort of compression problems. I should be able to add any effect without causing problems with the picture. And it's not on every shot, only a few select scenes. It's not a specific color (like Reds) either.

I'll try the 3-way filter today.

Boyd Ostroff · May 20th, 2005, 02:37 PM

That's odd. Try this experiment: create a new empty sequence and drop a clip into it. Does the bar above the track turn green or is it light blue? If it's green then that indicates FCP wants to render the sequence. That would mean something is mis-matched between the clip and sequence settings, and that might be the culprit. Carefully look at the properties of each.

If the bar is blue, then do you see the blockiness in this new sequence? Does it look different than opening the clip itself in the viewer?

You said the original clips look clean, so this probably isn't the problem, but there has been a lot of discussion about noise in DVX-100a footage under certain conditions. I'm not personally familiar with that camera, but it might be worth digging through our DVX forum to read up on this issue.

Glenn Chan · May 20th, 2005, 02:45 PM

Hi Tim,
I don't think the 3-way Color corrector filter would help. My advice would only apply to the 3-way CC filter bringing out artifacts in DV-compression video.

I would look into what Boyd is saying (your problem may be a settings mismatch).

Something else that may help is to get properties on your footage. Check that they are DV... and not PhotoJPEG or something like that.

Tim Clark · May 21st, 2005, 12:15 PM

Well, the 3-Way CC didn't work. I fooled around with most of the options, one at a time, and it didn't make it better.

I copied one of the bad scenes and pasted it into a new sequence, and the system wasn't looking to render it at all. It stayed gray. I have a feeling it might be a problem with the DV footage coming directly from the camera.

If anyone has any other suggestions, I'd appreciate it. Thanks for the input so far.

Boyd Ostroff · May 21st, 2005, 12:37 PM

Quote:

Originally Posted by Tim Clark

I have a feeling it might be a problem with the DV footage coming directly from the camera.

This would have been one of my first guesses, but you said "However, when I look at the original footage in the bin, it is not there.". If it looked OK when double-clicking it in the browser to open in the viewer, then it must have been captured without problem. Or are you now not sure your original statement was correct?

Tim Clark · May 21st, 2005, 06:05 PM

I opened up the original images in the bin. They are okay, but not perfect. I found that by making even slight adjustments in the contrast, or tweaking the color just a little bit, that the problem surfaces.

The image is "fine" before I touch it, but the image does need to be tweaked with some color correction so I can't leave it as-is. But whenever I do just about anything to it, it starts causing the image problems.

That's what leads me to believe that it's in the original images. The problem is there, just waiting to jump out.

Boyd Ostroff · May 21st, 2005, 06:42 PM

Oh, well in that case it sounds a lot like that's just the way your footage is. Unfortunately, depending on the nature of the scene, exposure, etc, you are limited in how much manipulation can be done without having problems like these...

Doug Fearman · May 23rd, 2005, 09:39 AM

I'm glad you brought up this issue Tim. I'm having the same problem only with footage I shot last week on a panasonic GS-70. Initially I thought it might be a bad vid card but I don't think so. And for the life of me I can't figure out what's causing it. I appreciate the input from everyone and will see if using these suggestions fixes the problem.
doug

May 20th, 2005, 01:11 PM	#1
Tim Clark MicroDolly Hollywood Join Date: Feb 2005 Location: Burbank, CA Posts: 22	Pixelation/Compression Problem I'm having a little trouble with some of the images I'm capturing and wondering if anyone can help. I've got FCP4 and I'm downloading footage into my External Hard drive from my DVX100. I'm not shooting in the progressive 24p mode and all my settings are correct for DV in Final Cut. I have added some filters, including widescreen and color correction, but when I view my footage in the timeline I can see pixelation in the background colors. The background walls will have pixelated boxes with lighter and darker boxes that will move and swirl about behind the talent in the shot. I will see this pixelation in the canvas, but I will also see it in the DVD that I burn from DVD Studio Pro. So, I'm sure it's not just "playback" quality. A computer-geek friend of mine says it's a problem of compression, but I'm not sure where the problem is. I've got all the capture and render folders in the same external drive, all going through FireWire. And all the footage has been properly rendered. I've even tried to desaturate the color so the computer won't try so hard to find the "correct" color on that background. He suggested that I re-capture the footage and try again, but it's happening in nearly every project I start. Anyone dealt with this? __________________ www.microdolly.com Jibs, Dollies, Camera Mounts

May 20th, 2005, 01:39 PM	#3
Tim Clark MicroDolly Hollywood Join Date: Feb 2005 Location: Burbank, CA Posts: 22	I did not use the 3-way corrector, only the basic corrector. I'll give that a try. Will the color smoothing make the picture any less sharp or more out of focus? When I turn off the effects, the problem is still there. However, when I look at the original footage in the bin, it is not there. Which is why I was concerned about some sort of compression problems. I should be able to add any effect without causing problems with the picture. And it's not on every shot, only a few select scenes. It's not a specific color (like Reds) either. I'll try the 3-way filter today. __________________ www.microdolly.com Jibs, Dollies, Camera Mounts

May 21st, 2005, 12:15 PM	#6
Tim Clark MicroDolly Hollywood Join Date: Feb 2005 Location: Burbank, CA Posts: 22	Well, the 3-Way CC didn't work. I fooled around with most of the options, one at a time, and it didn't make it better. I copied one of the bad scenes and pasted it into a new sequence, and the system wasn't looking to render it at all. It stayed gray. I have a feeling it might be a problem with the DV footage coming directly from the camera. If anyone has any other suggestions, I'd appreciate it. Thanks for the input so far. __________________ www.microdolly.com Jibs, Dollies, Camera Mounts

May 21st, 2005, 06:05 PM	#8
Tim Clark MicroDolly Hollywood Join Date: Feb 2005 Location: Burbank, CA Posts: 22	I opened up the original images in the bin. They are okay, but not perfect. I found that by making even slight adjustments in the contrast, or tweaking the color just a little bit, that the problem surfaces. The image is "fine" before I touch it, but the image does need to be tweaked with some color correction so I can't leave it as-is. But whenever I do just about anything to it, it starts causing the image problems. That's what leads me to believe that it's in the original images. The problem is there, just waiting to jump out. __________________ www.microdolly.com Jibs, Dollies, Camera Mounts

May 23rd, 2005, 09:39 AM	#10
Doug Fearman Regular Crew Join Date: Oct 2004 Location: upstate new york Posts: 97	I'm glad you brought up this issue Tim. I'm having the same problem only with footage I shot last week on a panasonic GS-70. Initially I thought it might be a bad vid card but I don't think so. And for the life of me I can't figure out what's causing it. I appreciate the input from everyone and will see if using these suggestions fixes the problem. doug __________________ Would someone turn on the lights!?

May 20th, 2005, 01:21 PM	#2
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	Are you using secondary color correction in the 3way CC filter? If so, hit the show mask button and see if you see the pixelation/blockiness there. The 4:1:1 color smoothing filter may help a little, along with the softness settings in the 3way CC (drag the bottom sliders out so it the limit effect settings look like chopped off pyramids). 2- With no effects, do you see your problem?

May 20th, 2005, 02:37 PM	#4
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,797	That's odd. Try this experiment: create a new empty sequence and drop a clip into it. Does the bar above the track turn green or is it light blue? If it's green then that indicates FCP wants to render the sequence. That would mean something is mis-matched between the clip and sequence settings, and that might be the culprit. Carefully look at the properties of each. If the bar is blue, then do you see the blockiness in this new sequence? Does it look different than opening the clip itself in the viewer? You said the original clips look clean, so this probably isn't the problem, but there has been a lot of discussion about noise in DVX-100a footage under certain conditions. I'm not personally familiar with that camera, but it might be worth digging through our DVX forum to read up on this issue.

May 20th, 2005, 02:45 PM	#5
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	Hi Tim, I don't think the 3-way Color corrector filter would help. My advice would only apply to the 3-way CC filter bringing out artifacts in DV-compression video. I would look into what Boyd is saying (your problem may be a settings mismatch). Something else that may help is to get properties on your footage. Check that they are DV... and not PhotoJPEG or something like that.

May 21st, 2005, 06:42 PM	#9
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,797	Oh, well in that case it sounds a lot like that's just the way your footage is. Unfortunately, depending on the nature of the scene, exposure, etc, you are limited in how much manipulation can be done without having problems like these...