HELP! Vegas Is Haunted!

Jay Gladwell wrote on 6/15/2006, 4:55 AM

Got a DVD from a client (that's all he had) and have been asked to correct some problems. One problem was there were some video dropouts. I have gone in physically removed the two frames where the dropouts were and replaced with one frame before and one frame after.

When I view the video in Vegas there are no dropouts. When I proof the mpg file prior to burning there are no dropouts. After I burn the disc and view in DVD player on a standard television, the dropouts are back!

Does anyone have any idea as to what's going on here???

Thanks!

Comments

JJKizak wrote on 6/15/2006, 5:10 AM

Only thing I can think of is your burning the old file by mistake. Very easy to do unless you rename it. Just a thought.

JJK

Jay Gladwell wrote on 6/15/2006, 5:29 AM

Thanks for the thought, I had that one right off the bat. So I deleted the first file and re-rendered. Same problem.

This really has me baffled!

craftech wrote on 6/15/2006, 5:49 AM

Jay,

Render it to an avi file first, then render that to Mpeg 2.

John

farss wrote on 6/15/2006, 6:46 AM

Are they really dropouts or is there something in the source that's causing the encoder to loose the plot?
I've had something like this happen with stobe lights during a dance performance.

Jay Gladwell wrote on 6/15/2006, 7:30 AM

John, I've gone back and nearly started from scratch. It's rendering to mpeg now. If that doesn't work, I'll try the .avi, although I was hoping to avoid a step.

Bob, actually the real offender was during a static graphic (which I had to duplicate and replace), so there was nothing going on that would create the error you were suggesting... at least none that is visible to the nake eye!

Thanks, guys.

Former user wrote on 6/15/2006, 7:34 AM

You might want to make an AVI to verify that the black frames don't appear there. I wonder if this is the random black frame issue that has cropped up occasionally.

Dave T2

Jay Gladwell wrote on 6/15/2006, 7:41 AM

Dave, these aren't black frames. These are frames with video dropout. See sample here. Although the one that is giving me fits is on a graphic.

Chienworks wrote on 6/15/2006, 7:47 AM

One issue i've seen very occasionally is that sometimes timeline preview decodes MPEG frames differently than the rendering engine does. It's quite possible that it is a decoding error rather than a data error. What this means is that the problem may occur on one particular frame while previewing, but when the decoding happens for rendering it might be on a different frame. So, what you might be doing is cutting out a frame where the error appears, rather than a frame with the error, if you can follow what i mean. When rendering, the same error occurs but at a different place. Then the correction you made is to the wrong spot in the video!

This is why the suggestion to render MPEG to AVI before editing is a good one. After doing that there is no more MPEG decoding going on so spurious problems caused by the decoding remain static rather than becoming a wild goose chase while editing.

farss wrote on 6/15/2006, 7:49 AM

Nasty.

OK, just a wild guess. How are you previewing your edit?

Big trap with the Vegas preview window, it may only show one field. So say you have a dropout in field 2 but Vegas only shows you field 1, you think you're safe but when you render there it is.

Been caught out like this before. Client had done a freeze frame in FCP but it was de-interlaced, he'd stretched the still frame for a few seconds and what a mess. He didn't see it in FCP either so vegas isn't alone in this.

Bob.

Jay Gladwell wrote on 6/15/2006, 7:49 AM

Thanks for the explanation, Kelly. That does make sense. I'll give that a try for sure now.

Jay Gladwell wrote on 6/15/2006, 7:51 AM

Bob, I preview in the Vegas preview window and an external monitor (CYB). I'm hoping what Kelly suggested is the problem. Will let you know.

Thanks!

[edit]

Based on what John and Kelly suggested, I've canceled the mpeg render and started an avi render. (Got my fingers crossed!)

farss wrote on 6/15/2006, 8:17 AM

Ha,
ya think ya safe with external preview?
Nah, depending on your preview settings if frames are being recompressed then Vegas seems to only process one field and interpolate or something like that.

To really see these nasties you need to set Preview to Best Full.

I've always found it safest to trim one extra frame either side of where I can no longer see them (the dropouts) and internal preview seems to work best as it's stable and you get to see both fields merged.

Bob.

Jay Gladwell wrote on 6/15/2006, 8:23 AM

Yes, Bob, they are set to "Best" when previewing for the very reason you mention.

johnmeyer wrote on 6/15/2006, 8:38 AM

Since you've tried all the usual things, then if you have the QuantizeToFrames script handy, I'd try running that. One of the earlier posters mentioned that it might be possible for different encoders to grab different frames. I think this might actually happen if your frames aren't exactly aligned on frame boundaries. Even in Vegas 6.0d, there are still all sorts of small bugs waiting to happen when it comes to how video segments align. This is a tough problem in a product that lets you mix virtually every video and format under the sun.

I didn't write the Quantize to Frames script.. It was written by Randall Campbell who also wrote the excellent Veggie Toolkit, which you should check out here:

Veggie Toolkit from Peach Rock Productions

Here's the link to the QuantizeToFrames script:

QuantizeToFrames.js

Jay Gladwell wrote on 6/15/2006, 8:59 AM

Thanks, John, I'll check that out!

Jay Gladwell wrote on 6/15/2006, 11:01 AM

Well... I'm surprised. Rendering out to avi first did not fix the problem.

Former user wrote on 6/15/2006, 11:06 AM

Then it sounds like the problem might be in the original capture.

Dave T2

Jay Gladwell wrote on 6/15/2006, 11:17 AM

Dave, I've wondered about that. It's not the capture, it's on the DVD.

At any rate, I went back and captured the DVD onto DVCAM tape and then captured that into Vegas. Next, I went back and cut out the offending frames. Then, on another track, above the "blank" area of the original track where the frames had been removed, I inserted two full seconds of "clean" frames.

Still, in the final render those "ghostly" frames return! I have no idea what's going. I waiting to hear back from the client to see if he has another DVD that has no dropouts. If not, he'll have to live with it.

jrazz wrote on 6/15/2006, 11:30 AM

Jay,
If you don't mind me asking- are you charging the client for Murphy's law on this one or do you eat it? I tend to deal with this dilemma a lot. Something that should take 2 hours tops winds up taking 6. Just curious,

j razz

Jay Gladwell wrote on 6/15/2006, 12:07 PM

No, I'm eating this one. Two things I don't charge for:

1.) My mistakes.

2.) Those of Mr. Murphy.

Tom Pauncz wrote on 6/15/2006, 2:26 PM

Jay,
Just a thought. Have you thought of or tried to rip the material from the DVD as opposed to capturing to tape then capturing that tape with Vegas?

Perhaps you could work with the original VOB file from the DVD?

Tom

Jay Gladwell wrote on 6/15/2006, 2:40 PM

Yes, Tom, I tried that first. Thanks!

farss wrote on 6/15/2006, 2:44 PM

Two thoughts come to mind.

1) Are you certain it's clean media. I'd try generated media first just to make certain.

2) DVD is UFF and dropouts are field based. This one I can't really see how it'd cause a problem but I've seen some funky cuts cutting UFF media and then rendering to LFF.

3) Are these same dropouts that you're seeing or more dropouts?

Bob.

vazbul wrote on 6/15/2006, 3:40 PM

Hi!, I had once exactly this problem with digital drops. I was using Avis Express with a Miranda DV Bridge capture card and each time the software started rendering this kind of drops apeared. They were missing pixels that the capture card was making. The original media was OK. Try with another capture card. In more professional envirmoments they apear if your system does not have a nice reference signal in the VTR (s), capture card (decklink) or camera.

I hope this help, regards form Mexico and Excuse my english.