DV capture quality sucks

cooldude859 · Member Joined: 12 Dec 2007 Location: United States

Hi

I have a Panasonic GS85 and have been capturing via firewire. Aside from the expected interlace lines, I am getting some kind of vertical pattern that odesn't move with the video. It basically causes the video to look like hell. Even after using a high quality deinterlace in virtualdub, the verticals are still there. I have seemingly tried everything from different capture programs. Removing every possible DV codec and installing others. I even transferred a captured file to another pc and still see the problem.

But, my old pc has a capture card(composite) so I tried capturing that way. Obviously, not as sharp a picture but NO ARTIFACTS. Much more useable than the DV capture.

I don't really get it. I have seen others across the net complaing about the mysterious vertical lines but have found no solution to this. Is it caused by the camcorder?

I hope someone can solve this one. I like the crisp image DV gives. But I hate the artifacts.

Thanks for any help.

edDV · Posted: May 22, 2008 01:08

Baldrick · Administrator Joined: 09 Aug 2000 Location: Sweden

Moving you to our dv forum section.

cooldude859 · Member Joined: 12 Dec 2007 Location: United States

Here's a screen shot. The lines are more apparent on my widescreen LCD monitor. Not so apparent on my 15" CRT. But still there. The photo doesn't look as bad as the movement in the video.

Thanks.

JohnnyMalaria · Member Joined: 29 May 2006 Location: United States

Your image is 1280 x 960 and so it has been enlarged (presumably from playing full screen). The artifacts may or may not be due to that.

You need to capture a frame at its native resolution (720 x 480) and post that so we can see if the same artifacts are present. You should do that from VDub and from Windows Media Player to compare (they should use different decoders).
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filmboss80 · Member Joined: 31 Jan 2007 Location: United States

I think I know what the OP is talking about with the vertical banding, as I have seen it in dark scenes when working with Japanese footage (0 IRE?) in the DV format. I used both Panasonic and Cedocida codecs and got the same results. The problem worsened with title keys and effects (recompression) in the editor's timeline. Never figured it out. I was thinking maybe the OP got a camcorder with the black level set low. Can't be sure if that would affect anything. Maybe some of you can enlighten us.

2Bdecided · Member Joined: 21 Nov 2007 Location: United Kingdom

Is it around colours and colour boundaries, looking like a kind of mesh when there is movement?

If so, it's probably NTSC DV 4:1:1 chroma, and the (bad) way it's being decoded on your machine.

The composite capture just smears it.

Just a suggestion - it might not be that.

Cheers,
David.

edDV · Posted: May 22, 2008 12:01

VLC is also good at snapshot directly from the DV-AVI file. It would be a good crosscheck on any artifacts added by Vdub DV codecs. Snapshot is under the "Video" tab.

Also VLC is good for deinterlacing DV playback. You will also find "Deinterlace" under the "Video" tab. "Disable" shows pure 480i (interlace). Try "mean" for 720x480p deinterlaced display. Below you see the results on the horizontal stock ticker.

480i direct DV-AVI

VLC "mean" deinterlace from DV-AVI playback.

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cooldude859 · Member Joined: 12 Dec 2007 Location: United States

Hey thanks for all that helpful info. After some careful reading I stumbled onto trying to "properly" deinterlace the video. At this point I was willing to try everything. I found a really neat tutorial for using Twixtor and FieldsKit to fix the video. I was skeptical but it worked very nicely. Surprisingly, it removed all the artifacts and interlacing without destroying any of the quality. It also converted the 60i>60p>24p with amazing results.

Sorry if I sound like a salesman but I feel a huge sigh of relief considering the hours of frustration. I am on my old pc so I can't post the capture, yet, but will try over the weekend. It really does look a lot more like film to me.

filmboss80 · Member Joined: 31 Jan 2007 Location: United States

Hmm... Your initial description was of a vertical pattern. Deinterlacing plug-ins like FieldsKit usually remedy horizontal interlace artifacts. I, too, would be real interested in seeing a good quality screen shot of your original problem.

JohnnyMalaria · Member Joined: 29 May 2006 Location: United States

aedipuss · aBigMeanie Joined: 25 Oct 2005 Location: 666th portal

doesn't look like banding to me. more like typical square pixel diagonal line jaggies. it's compounded with deinterlacing as you've only got every other line, leaving out the smoothing of the in between lines. you can see it in the yellow stars also.
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JohnnyMalaria · Member Joined: 29 May 2006 Location: United States

I don't agree

Look at these two samples. After deinterlacing, there are notable vertical bands (e.g., the upper horizontal edges of the star) that are more than two lines tall even in a region of the image where there are no interlacing artifacts.

aedipuss · aBigMeanie Joined: 25 Oct 2005 Location: 666th portal

your eyes must be better than mine, all i see are jaggies above and below the diagonal lines and no banding in the center of the star where there are no lines. the jaggies may join together where they are close, and look like banding. but i think it's just where the red pixels intruded into the yellow pixels at the corners of the squares. and the same with the yellow into the red areas. but what do i know

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JohnnyMalaria · Member Joined: 29 May 2006 Location: United States

I guess using MS Paint in a hurry didn't help.

Here's a different take:

As it happens, a couple of days ago I did notice this when play a DV file in WMP. I can't recall the details though (which PC, OS version, display etc etc).

jagabo · Member Joined: 09 Dec 2005 Location: none

JohnnyMalaria · Member Joined: 29 May 2006 Location: United States

But in edDV's example, aren't both images decoded with the same DV decoder but in one case displayed as-is and in the other the already decoded image is deinterlaced by VLC?

If it were just 4:1:1 sampling, I'd expect to see it both images and the bands should be 4 pixels wide, not 2.

edDV · Posted: May 24, 2008 12:08

vhelp · ..Semi Neutral.. Joined: 31 Mar 2001 Location: New York

These are just theories mind you, because the true origin is not known, and the steps that
lead to the final posted image are also not fully known.

The images that edDV posted are a bit hard to decirn because they seem to be from an analog
type source and they are pretty blurry. That indicates to me some equipment filtering had been an
internal part of the system or user-applied. Never the less, you can't really completely rule one thing
here because anything that comes from broadcast (tv) are almost always full of errors of one sort of
another. So, everything else following that fact are pointless.

The other factor is relying on a softwares filter function. Personally, WMP and VLC do not quite appeal
to me, and I wouldn't rely on certain features of them when analizing a video or frame is important.

As an example, that pic he posted could already have sub-sampling errors from within the source level
before he captured it. Plus, noisy interlaced sources are usually desceaving in filter outputs.. ie,
the deinterlace function. Besides, he was just posting a deinterlace example

Now, given the facts of todays software and their upgrade/version issues, if I needed to export a
single frame from a video I would perform this function from my own image tools and just skip these
known applications (WMP and VLC are examples) all to gether and review/analize them for my own
purposes.

edit: I didn't read the whole discussion, so I missed jagabo's and edDV's followup
posts. Sorry bout that fellows

-vhelp 4687
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jagabo · Member Joined: 09 Dec 2005 Location: none

Undead Sega · Member Joined: 03 Apr 2007 Location: United Kingdom

what is 4:1:1 Helper???

jagabo · Member Joined: 09 Dec 2005 Location: none

4:1:1 Helper is a filter for VirtualDub:

http://www.geocities.com/xesdeeni2001/

Undead Sega · Member Joined: 03 Apr 2007 Location: United Kingdom

cool, but what does it to exactly? looks interesting.

jagabo · Member Joined: 09 Dec 2005 Location: none

NTSC DV subsamples color at 1/4 the resolution (on the horizontal dimension) of the brightness resolution. In other words, the luma channel is 720x480 but the chroma channels are only 180x480.

When converting this to RGB some programs resize the 180x480 chroma planes using a simple nearest neighbor (aka point) resizing. 411 Helper fixes that by smoothly interpolating the colors channels.

Undead Sega · Member Joined: 03 Apr 2007 Location: United Kingdom

ohh right, does this also go for PAL DV?