Bad rectangular blocks in video (Urgent)

[defaulk9]

Hi fellas.

I'm in a bad spot here. I have video that for some reason is acquiring green blocks. They are usually 8 pixels high and something like 34px wide and they only last for a frame. They happen randomly througout the video but if I close the player and re-open the video, the green blocks will still be in the same position on the same frame. What could be causing these?

http://dfalk.myftp.org/bad-dv.jpg

A little history: I originally had a lot of them in my source material. I capture using a dv camera and firewire. When I noticed them, I re-captured my material and the second time I captured I saw no blocks.

But I needed to run some of that clean material that I re-captured through some filters in VirtualDub, and when I did this, the resulting video came out with the same green blocks.

Because the bad blocks happen in the same place every time, I'm thinking that it must be corruption in the file itself, meaning it must have been encoded bad, and not decoded bad. But if that's the case, why does it happen when doing a straight capture? I thought that no encoding occured during a firewire capture and that it was just a data transfer?

Please give me some advice on this. It's pretty urgent that I solve this problem.

Thanks!

[Video Dude]

Those green blocks look like video dropouts.

Hook up the camcorder to a TV and see if you green blocks appear (or another similar artifact). If you see the green blocks, then the DV tape has most likely gone bad. This happens sometimes when you reuse a tape many times or even if the camcorder heads are dirty. It seems to happen more if you use LP speed rather than SP. There is really nothing you can do to fix the tape. It would be smart to transfer the video to your computer and then export to a new tape so you don't get more green blocks as the old tape degrades more in the future.

There is really no way to filter out those green blocks. If it just a few frames then you can cut the green block frames out during editing. But if they are in many frames, then this cutting process would make you video look rather jerky in motion.

[Guest]

But I needed to run some of that clean material that I re-captured through some filters in VirtualDub, and when I did this, the resulting video came out with the same green blocks. It sounds like you are saying the video had no green blocks until you applied filtering to it in VirtualDub. If so, what filters did you use?

[Mug Funky]

green blocks don't happen on a DV camera, so they're probably not on your tape (DV's error concealment strategy is to repeat the same block from the last good frame, which explains the "swishing" look you get when fast-forwarding). the green blocks are probably happening on your computer. so you don't have to worry about your equipment at least :)

try capture with a different program. there's a few out there. i like scenalyzer, but it watermarks random frames on the free version. the upside is you can capture DV with low enough CPU/HDD pwnage that you can safely minimise it and use firefox for a while when waiting for your capture.

filtering during capture is a bad idea IMHO - too much risk of framedrops, and if none there, too much risk of directshow somehow doing weird things to your video. hard disk space is cheap, and DV is quite low bitrate for a "mastering" format (4:1:1 sampling is not good enough IMHO). best capture without filtering, back it all up to DVDs and filter it later.

[defaulk9]

filtering during capture is a bad idea IMHO - too much risk of framedrops, and if none there, too much risk of directshow somehow doing weird things to your video. hard disk space is cheap, and DV is quite low bitrate for a "mastering" format (4:1:1 sampling is not good enough IMHO). best capture without filtering, back it all up to DVDs and filter it later.

I wasn't filtering during capture. I re-captured the video a second time. Then I ran filters on that after it was all captured. As far as DV covering errors by repeating the last good frame, well that's how it looks in Virtualdub. It repeats the last frame, which makes it easy to miss the errors.

Working in premiere however, they show up as green blocks. I'm not sure why.

It sounds like you are saying the video had no green blocks until you applied filtering to it in VirtualDub. If so, what filters did you use?

Only deshaker.

[Guest]

Only deshaker. What happens if you don't use Deshaker?

[defaulk9]

you mean and just copy the original using full processing mode in vdub?

[Guest]

Of course, what else would I mean?

You said the video was clean before applying filtering. I'm trying to verify that.

[defaulk9]

nothing happens. But now I'm not blaming deshaker. My camera is now displaying thick blue bars across the picture in playback so something is terribly wrong :devil:

Needless to say I'm pretty sure it is my camera that has caused this awful mess. Erg.

Thanks for your help guys. Guess it's time to buy a new camera or something.