Frames from other videos??? - WTF?

Gambo · #1 (**permalink**) 04-11-2005, 09:51 PM

Right here goes!

I don't know if this site is for amateur/professional (or both) editors, but I have stumbled upon a problem that no-one can solve! If anyone knows an answer then please please let me know!

I've been editing videos for about a year and the company I am currently freelancing for have a G5 2ghz dual Apple Mac with Final Cut Pro, with a full setup (inc, AJA IO box, DSR, BetaCam, Black and Burst Signal generator, SCSI hard drive - the works).

About 6 months ago, we were working on a huge project (1 render file was 250gb!) with an awful lot of assets. We started getting rogue frames randomly through the video.

These frames were either green and pink (which I believe could be a sync problem), but also frames from other projects?!? They can be from projects that are no longer on the system. We would re-connect or re-capture the footage and the problem was gone, but would then appear in another part of the video.

This has carried on until present. The project has finally been finished, but it now happens with other projects! Technicians don't understand it, Apple don't get it, and I sure as hell don't!!!

The system has been replaced, aswell as other components, and we think we've narrowed it down to renders!

When the footage is captured - its fine!
When imported into Final Cut Pro - it's fine!
But when its rendered - this is when the problem can arise (but it is completely random - sometimes it won't happen - other times it does it all the time!)

The other day I captured in a 2min video from DV Cam, Rendered it 8-bit uncompressed and exported it out as an Mpeg2 - rogue frames?

If anyone can help - or has any questions - let me know!

Thanks

Gambo

skratakh · #2 (**permalink**) 04-11-2005, 11:03 PM

well to me it would seem as though the hard drive requires defragging, though if the system has been replaced this couldn't really happen, plus i haven't defragged or know how to defrag a mac. keep updatin cos i'd like to know how it goes.

Gambo · #3 (**permalink**) 04-12-2005, 12:07 AM

we've defragged it, re-formatted it and changed it!

It was suggested that it could happen when the system crashes (but apparently macs don't crash! (or so they say!).

This though would not explain why the problem can occur during rendering!

You know in Gremlins 2 when they catch the gremlin in the phone system? Well I think we've got one in our machine!!! Moving shit around and stuff!

We've just got in another/new G5 2.5 dual today to work on while the other one gets taken away - they've done this before though and couldn't find anything!

I really want to know whats going on though because its costing a fortune to sort out! As you can imagine!!!

mrlipring · #4 (**permalink**) 04-12-2005, 01:05 AM

this definitely sounds like there's been a problem writing to or reading from the hard disk.

When a FAT has become corrupted in the past, i've had trouble playing mp3s. They've become corrupt, and played ok up to a point, then there's been half a second from another song, or another song that's been deleted, like you describe.

Obviously, when a file gets deleted, it doesn't actually get overwritten, it just gets deleted from the FAT. If something hasn't properly been deleted from the FAT, but the sectors it uses have been overwritten, or the FAT is pointing to the wrong place, like you're describing, it can really balls things up.

Obviously, i'm talking about windows stuff here, but i'm assuming that macs use a file allocation table of sorts, and that it's becoming corrupted.

If i was getting stuff like this happening, i'd be thoroughly stress testing the memory, cpu and hard disk. Leave it testing for a week if need be. There's something very wrong there. My guess is, it's corrupted FATs.

Gambo · #5 (**permalink**) 04-12-2005, 01:50 PM

thanks for your view mrlipring.

I'll suggest it to the techi. I, like you, no virtually nothing about the insides of a mac. Sure, they look nice and sexy, but they don't half do my f***ing head in! Atleast I know where I am with a PC - if they've got a problem then 9 times out of ten they tell you what it is, Macs on the other hand tend to go all pussy on you! That's my view anyway - I apologise if i'm wrong!

The wierd thing is that the hard drives have 'apparently' been changed a couple of times - but i'm sure that they kept some components of the original system.

This certainly sounds like a valid theory, but would it affect a clip that had only been captured through DV Cam, and exported straight out as an .m2v? This clip wasn't even played on the timeline! The system does have to render it - obviously, but it wasn't actually saved on the system at all!

We also use SCSI drives with the system and one died a couple of months after the problem started, so it was replaced. This could have affected it, and when it was replaced the main hard drive wasn't, so I'm not sure if its something that can be passed between drives or not? (If you know what I mean!!!)

Being an editor, this problem is my absolute nemesis (as you can imagine!).

A reply would be great, Cheers

Gambo

mrlipring · #6 (**permalink**) 04-12-2005, 03:56 PM

the chances are that during any processing, the datastream is buffered (or buggered, in your case) on the hard drive. Virtual memory. Whether you saved it to the dodgy drive or not, it was possibly on there at one time.

Gambo · #7 (**permalink**) 04-13-2005, 03:57 PM

One thing I didn't mention about this problem (or rather something that happened to the original project) was this:

At the peak of all the problems, when we were just getting totally pissed off with it, we exported the video out as .mov. We watched it and there were 2 dodgy bits. We noted the timecodes and sent the mov to our DVD guy (who works on the other side of town and uses a pc). He patched over the glitches and exported it out as an .m2v, right?.

There were 3 new glitches on the video! This was a total one-off but can you explain it? Or is that just too messed up?!!!

Cheers

mrlipring · #8 (**permalink**) 04-14-2005, 12:22 AM

You need a bloody exorcist mate, not a technician.

Gambo · #9 (**permalink**) 04-14-2005, 08:04 AM

Ha Ha, thats exactly what I thought! Or a Sledgehammer!

This was only a one-off but it really took the piss! Do you know what I mean?

Gambo · #10 (**permalink**) 04-14-2005, 08:10 AM

Actually, while I've got your attention, there's one other thing that happens very very occasionally.

I don't know how hot you are on FCP but sometimes cross dissolves look a bit fucked up - frame blending wise. They sort of judder around. If you can't help on this one don't worry about it. Like I said its only happened a couple of times on that one mac.

By the way, what sort of films do you make?

Gambo