Pixelation Problem

G

gianpl

Member
Here I am again....with of course, more problems

I shot on 24p on my DVX100A and for some reason the footage looks pixelated in some parts, like edeges and shirts when imported into my computer.

Does this happen to anyone???
Is it a setting on the camera ??? detail level or something??? what detail should i use?

is it a setting in fcp???

or it is just because its playing on a computer and when played on a TV will looo just fine....?

Please I really apreciate your help....

I used JVC MiniDV tapes.
 
Yeah, if it's red, that's the problem. I always get pixelation though, regardless. I popped in a DVD to see if I still got this. Results were very similar. Things seem clear on my TV. Test your results on your TV first.
 
That is a fault of the DV codec, but rest assured it is fixable. What NLE do you use? If you use vegas, simply insert the "chroma blur" filter onto the offending clip, adjust the horizontal blur until it goes away. Other NLE's have this function as well, but I'm not as familiar with it.
 
Im using FCP....

Could it be that im using a 1ccd minidv sonycamera from the year 2000 to capture my footage into the computer????????
 
Nope! It's there for all DV footage with bright reds. You can use the 4:1:1 smoother under "keying" but it screws up the edges and reappears when you re-compress. My advice: don't bother doing anything. If your footage is destined for DVD you might bother, if it's destined for DV tape, it won't do any good at all.
 
it is destined for a webpage.....should i still not worry???

thanks a lot for your quick responses guys ....you guys kick ass
 
No andre, this problem is not only limited to the DVX, I have seen it with the XL2, PD170 and even a 1chip TRV20. It has to do with overly saturated colors and the DV codec. Yes you should still take care of it if you are going to web, and as policar said, if you go back to the DV codec it will reappear, which is why I never use the DV codec for my final product, I usually go with Quicktime Motion-jpeg which preserves all the quality, same size as DV codec, but much better compression. I don't know about the FCP filter, but the vegas filter does a terrific job in getting rid of this DV artifacting, with no damage to any other part of the footage. I would think that you could get similar results with FCP.
 
DV codec artifacts are very well known and documented these days. Chroma-patterning is not a DV artifact. I would be happy to get info about this artifact...maybe you are confusing this patterning with the well known Quilting in DV but this is another story. B.t.w. DV codec is an enhanced form of motion-jpeg whereby it is known that for the same size, M-jpeg can't compete with DV codecs. I am also interested to know where I can find any info about chroma-patterning with the other brands you mentioned.
 
Andre, the problem he's experiencing is CLEARLY the 4:1:1 color space from DV codec. Yes, the dvx has unique issues beyond that, but they're not nearly as noticeable, and what he's describing is EXACTLY the problem you get from DV artifacts.

Personally, I work in DV since FCP is smart enough to keep compression generations to a minimum. (Usually meaning one generation of compression.)

If I wanted a super clean DVD, I'd then go into After Effects in uncompressed, do chroma blurring and noise reduction and unsharp mask, then output, but I don't care that much.

If your output is higher resolution than 320X240 I'd consider doing something about the artifacts. Otherwise, I'd just leave it be. FCP is a little bit unpleasant when it comes to smoothing chroma artifacts. You have to work in PNG or Animation or uncompressed, then create two layers of footage stacked on top of each other, then apply chroma blur to the top layer. Fun? No, but it's the only way to clean up artifacts without green edges around the frame appearing or artifacts reappearing.
 
Sorry, I just want to read something about this artifact. I don't need statements that it IS a DV codec related artifact. After about 25 years of having been involved in digital video design issues, including all kinds of transform-coded compressors for broadcast applications, I still want to learn...
 
Andre, This is indeed a well documented DV 4:1:1 problem, and occurs on the dvx quite often because of the color saturation available by this camera. Don't believe me, well do a test for yourself. Make a 0/0/255 red circle and lay it on top of a 255/0/0 blue background, or any color for that matter, but this is most pronounced. In your preview it should have good clean edges, and don't use the Avid DV codec becasue it has chroma blurring built in. Anyway, in the preview it looks good, now render it to a DV AVI, and play it back. Viola, horrible pixelated edges. IT is the 4:1:1 codec, you can do it yourself. Check the XL2 forum, there is a recent post on there about the same problem with the XL2. The problem that Adam wilt is explaining is different, and not noticeable at all, unless you are blowing up the image 200%. He even said himself that this is not a noticeable problem. Now, render that same red cirlce footage with the motion jpeg codec, and watch what happens. mutch better than the dv codec. just becasue something is derrived from one codec, and claims that it is better, does not mean that it is. Just look at HDV. It is a good codec, but has it's own problems with artifacting. I respect that you have worked in the business for a long time, but this is something that I have done lots of research on, and have found the reason why it occurs and how easily correctible it is. If you want me to post screen grabs just ask, I am more than willing to back up my research.
 
We are talking about the analog signal outputted by the DVX. So we talk about the DVX CCD signal being digitized/ processed/ HW compressed/ HW decompressed (recorded) and outputted by the DVX analog output. Pixelated edges well known in all tranform based compressors, don't show up as vertical spatially fixed patterns (stripes) on saturated/modulated colors. You don't have to blow up the pics to see this specific DVX artifact with saturated colors . Just download this .mov scene http://www.jesterrecords.com/dvx60i.mov shown by JesterJJZ in this forum. This problem has nothing to do with DV pixelization. I would appreciate to get the mail about the XL2 signal pixelisation.
 
Here, this was posted just a couple days ago, and if you do a search you will find many more instances.
http://www.dvxuser.com/V3/showthread.php?t=31517
We are not talking about analog out from the DVX, I don't know where you got that. The analog out, as you described has already been processed through the DV codec. This problem is well documented, and is why many NLE's today have a filter to correct the problem. Jesterriouses footage also has this, and by applying a quick chroma blur filter I was able to get rid of the offending lines. I am not talking aobut DV pixelization, it something completely different, and has to do with the way the 4:1:1 codec compresses colors.
But whatever the cuase, it is an easy fix, USE CHROMA BLUR and go from there. I will post pics in a minute, once I find them on my site.
 
Ok, here is some footage that I shot that suffered from the chromatic abberation. With a little chroma blur the problem was gone.

No chroma blur
nochromablur1.jpg



With chroma blur
withchromablur1.jpg




No chroma blur
nochromablur2.jpg


with chroma blur

withchromablur2.jpg



This last one has been blown up 200% so that you can better see the problem, and resolution.
chromatest.jpg
 
Plse read the starter post in this thread. No NLE, no blurr filters, no side stories involved, just about the DVX output. That's where I am talking about.
 
The "starter post" said he was using Final Cut Pro! You can't just ignore that! It's obvious what the problem is. Are there other problems? Yes. Are there other problems relating to chroma? Yes. Are there other problems relating to chroma specifically on the dvx? Yes.

Are these problems causing what he describes? 1000:1 odds says "no." I've gotten this plenty of times with all the dv footage I've shot. The dvx has hot reds and sharper everything else (progressive scan) so it's particularly apparent with it, that's all.
 
This is an interesting thread. Does anyone know if there is a chromic blur filter or an equivlent in Premier Pro 1.5 ?
 
Yes, andre, I realize this, but you HAVE to realize that any output from the DVX or any other DV camera for that matter already has been processed with the DV codec. That's what I'm talking about. :)
Maybe it is time for you to re-read the starter post, where in the very first sentance he says "when imported into my computer". Are you working with DV footage in some other way Andre?
 
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