OT: Pixels dropping out?

Lili wrote on 8/1/2005, 6:20 AM
I just captured a video I shot yesterday with a PD 170 that is fairly new and have never had a problem with. However, in this video, most of the clips (seems to be more towards the end of the 28 minutes of captured footage) have what first appeared to be little sparkles appearing and disappearing every few seconds.

Upon closer inspection, they look like pixels that have "dropped out" (if that can even happen). For instance - there is a shot of a red background, but instead of it being evenly red, some areas are white, or a pale color, and when the video is played, they look like sparkels of light.

FYI
I don't get any warning codes within the camera as to needing to be adjusted or cleaned. Although I shoot with the PD 170, I've been capturing with the Sony HC32, but that is also pretty new.

Does anyone know what this is a the cause? Thanks.
lili

Comments

GlennChan wrote on 8/1/2005, 12:08 PM
LP mode and differences in head alignment can cause dropouts if you use another camera to capture. Try the original camera.

2- in the past, mixing tape brands could cause dropouts because the lubricants interacted with each other. Sony and Maxell reformulated their tapes in 1997.

Liam_Vegas wrote on 8/1/2005, 12:56 PM
Were you in DVCAM mode on the PD170? Although I suspect not... as I doubt you would have been able to capture at all using the HC32 - but you never know.

If there is no reason why not... efeinitely trry capturing the tape using the PD170.
Lili wrote on 8/1/2005, 4:10 PM
I shot a video this afternoon and captured it with the PD170, but the the dropouts are worse (bigger and more frequent) than ever.

When you say don't mix brands, do you mean that once you start with a brand stay with it, or that I should use Sony tapes with the Sony cameras? I've been using Panasonic DV Master tapes - as they were recommended by the place where the PD170 was bought.

Spent a lot of time with the client setting up the shoot and everything looked great - now the video is totally unacceptable.

Once the dropouts occur, are they gone forever?

Thanks for the replies.
GlennChan wrote on 8/1/2005, 7:05 PM
In the past, Sony and Panasonic tape did not play well with each other. Having a Sony or Panasonic camera makes no difference.



In practice this may be difficult/impossible.

Basically if you encounter problems with tape brand mixing, then try a head cleaning tape. The head cleaning tape may clear up problems with dirt/stuff on the camera's heads, which is another potential cause of dropouts. Read the instructions carefully- improper use of head cleaning tapes can damage your camera's heads.



According to Adam Wilt's DV FAQ, you may have a chance of capturing dropout-free with a DV deck that has automatic tracking. DSR-1500 and DSR-1800 decks have tracking.

You can also paint over dropouts in Photoshop or compositing/rotoscoping programs. In Vegas this is really easy.
Duplicate the video onto itself. Shift the lower/upper video by 1 frame. (select the clip, hit 4 or 6 on numpad)
Go into the pan/crop tool
Click on mask on the bottom

Use the mask tool to cut out areas where dropouts occur. Below the video track will be the previous/next frame. So, this replaces the dropout area with picture from the next/previous frame.

If there's picture movement, you may need to export frames into Photoshop or a rotoscope or compositing program to clean up individual frames. Or do it within Vegas use the pan and masking tools.

Some other programs have dropout detection filters available I believe, although I don't know if that's feasible.

2- Is there something wrong with your camera? have you gotten it checked and professional cleaned (which is more thorough than a cleaning tape)?

From your post, it seems like you're saying you shot some more footage and that footage has more dropouts. That would indicate your camera has problems.

As opposed to...

You captured the footage you already shot with your PD170, and it's getting more dropouts now.

3-

Maybe.

Data is recorded onto DV tape as a bunch of 1s and 0s, with error correction. You get problems when those 1s and 0s are ambiguous. Some decks will read those 1s and 0s less ambiguously than others (a good example would be LP mode; the camera that shot the footage will read the tape better than others). Also, trying to re-capture can sometimes recover a different set of data (and you can merge the two manually).

If something was recorded poorly then the 1s and 0s on the tape simply aren't there like they're supposed to be. In that case, the information is gone forever.
johnmeyer wrote on 8/1/2005, 7:51 PM
If you connect a monitor to your camcorder, do you see the dropouts on the monitor as the tape plays back? Or, do you only see the dropouts on the captured video? If you see it on the monitor, then it is bad tape, dirty heads, mis-alignment, and all the other things previously mentioned. If it looks fine on the monitor, but bad after capture, then the problem has to do with the capture process.
Lili wrote on 8/2/2005, 7:06 AM
1. Had used the cleaning tape prior to making last video as the dropouts started (very minimally) 3 vids ago and got progressively worse with each new capture.

2. Played the vid on TV monitor and it plays perfectly.

The fix(es) suggested would be OK for small project, but there are thousands of dropouts in last vid, so that isn't an option at this point. Will try to recapture first and see what happens.

MIGHT this be a problem within the Vegas Capture mode itself?

Will let you all know the eventual outcome when resolution of problem is clear. Thanks a lot for your help!
lili
farss wrote on 8/2/2005, 7:42 AM
This is not a problem with Vegas's VidCap. Also dropouts will affect the audio quite badly as well, I usually hear them before I see them.
Certainly better decks MAY do better, the DSR 2000 is about as good as they get, mostly becuase I think it'll also play DVCPro tapes and therefore has wider tracking range.
If all else fails try this simple trick, play the tapes out of a good deck, and then feed the A/V into say an ADVC 110 or 300 and capture from that. Obviously use the best feed you can into the A->D converter, at least S-Video, if you can find a deck and converter with component so much the better.
Why you get less dropouts from the analogue deck outputs than down 1394 I really don't know, I picked up this tip from the guys at the Sony DV forum on COW. At first I thought they were nuts until I tried it and it really does work.
Clearly you need to investigate why this is happening, you could have something as simple as a major head clog, cleaning tapes will not clean major gummies on the head or it could be heads are out of alignment. Also bad weather conditions increase condensation inside the camera and that can cause big head clogs.
Bob.
Lili wrote on 8/2/2005, 9:03 AM
Bob,
Thanks for the info. Re the heads/camera being dirty, if that were the case, wouldn't the video also show the dropouts on the TV monitor? I tested it and vids played perfectly.

Just recaptured the same footage and still the same problem - whichever camera I recapture with.

I don't have a deck - they're pretty expensive where I live, but if I thought that would solve the problem I'd get one.

Have been using the same 2 cameras for over a year and have never had this problem. It's not likely that the heads on BOTH cameras would be dirty or have gone out of alignment at the same time, so this remains a mystery, but an issue I need to solve asap.
farss wrote on 8/2/2005, 2:12 PM
If you're getting the same problem in footage from two cameras then something sounds fishy. Have you tried capturing some old footage that used to capture OK?
Did you change type of tape in both cameras?
Try playing out of one camera via S-Video and use the other camera as A->D converter and see what you get. Theory seems to be that the analogue outputs have more error correction than what's sent down the 1394 cable.
Lastly try using a different capture app, Scenalyzer has just saved my bacon, there's a free eval version and that'll let you see if you're still getting visual dropouts.
Also when you get these dropouts is there anything happening with the audio, quite common to get a 'zzut' sound.
Bob.
Lili wrote on 8/4/2005, 10:45 AM
The "zzut" sound was there alright - an instant clue that something's dropping - not a sound I like to hear.

I called the place where I bought the camera and they said that with the volume of shooting I do, I should be using the headcleaning tapes more often. I had already done it once (for a ten-second duration) as recommended,, but they suggested I do it twice more --for ten seconds each.

So, I did that - recorded a 2 minuted video and captured it. The resulting clips were unrecognizable - they consisted of HUGE squares - like a patchwork effect!

Performed the identical test again and that time - everything looked normal! I will now do the identical test for a 3rd time and keep my fingers crossed that everything is back to normal and the camera transports just needed cleaning.

Strange though because it did not give me a message to that effect as it has done in the past. I've lost some confidence in this camera that I've always raved about - but I suppose any camera is bound to have glitches at some point.
Thanks for all your help.
lili
Former user wrote on 8/4/2005, 12:31 PM
I am not a big fan of cleaning tapes because of the abrasiveness and wear on the heads. But if you think the cleaning is helping, you might consider having the camera cleaned by a service professional. You will get a more thorough cleaning and less wear on the heads.

Dave T2
Lili wrote on 8/4/2005, 12:59 PM
That's very true, but until I buy a second camera, I don't want to be without it for even a week - which is how long I was told it would take - and 3 to 5 weeks if it was some other problem and they'd have to order parts from Kansas.

If that does become necessary, I'll have run out to get a back-up PD170 the same day because renting one's rather expensive.

It has been VERY hot and humid for about 6 weeks and I'm wondering if some of the outdoor shooting under the blazing sun- and then into a freezing A/C building may have contributed to the problem. I know for sure that's not good for any camera.
Former user wrote on 8/4/2005, 1:51 PM
I guess it is a tradeoff. Take a chance to not have work, or take a chance to lose the work you have (due to dirty heads) :)

Dave T2
farss wrote on 8/5/2005, 3:29 AM
Rapid temperature changes and high humidity will cause condensation inside the camera, very bad. Keep the cameras inside zip lock plastic bags or cases like Storm or Pelican with lots of silica gel. When the gear has gone from a cold place to a warm one let the whole case and contents warm up before opening them.
Bob.