FCP laying in the wrong footage, not respecting specified in-outs

So I'm happily editing along, and I do a routine mark in and out on my source, in on my record and hit F10 to lay in the shot... FCP decides to pick a different in point than I had selected in the source! Huh? I try it again. Same result. I quit, trash prefs, relaunch, and it does it again: Still refuses to hit the right in point on the source side.

I figure it must be a corrupted clip. So I move on to another take. Ten minutes later, working with a different clip, the system does it again. Lays in a different part of the take than I have specified.

This is midway through a project that I've been cutting for weeks using the same footage.

Any ideas what could be going on?

Thanks.

FCP 7
OS 10.5.8
QT 7.6.4

What format are you working with?



www.strypesinpost.com

What happens if you just drag the clip into the timeline?

What happens if you just let the wrong part go in, then Match Frame?

Move just that timeline and that clip into a new project file. Close the old project file. Test the behaviour. Same result, or not?


www.derekmok.com

Are you dragging the SAME sequence to the Edit to Tape window that you have made these IN and OUT point marks on? I can't tell you that I haven't made the mistake of dragging the WRONG sequence...or marking the IN point on the wrong sequence.


www.shanerosseditor.com

Listen to THE EDIT BAY Podcast on iTunes
[itunes.apple.com]

Eh, Shane. I believe he's talking about the usual insert/overwrite edit function in FCP, not about laying to tape.

Btw, I found that color coding the sequence that's going to tape can help.



www.strypesinpost.com

AH! I missed that. Zoning too much watching dailies.

That is odd behavior.


www.shanerosseditor.com

Listen to THE EDIT BAY Podcast on iTunes
[itunes.apple.com]

Yeah, this is a weird one. In the spirit of things that are weird, here's a weird question: How off is it? Is it off by like a few frames, or several minutes, or something in between? Is there any consistency at all to how off it is?

Regulars will have already guessed what I'm thinking. If it's consistently less than or equal to 15 frames, then I bet a nickel it's a GOP issue.

My initial guess is that it's DSLR footage in H.264. But I've no idea how you can cut h.264 for weeks (or maybe because of the constant rendering it takes weeks).



www.strypesinpost.com

Oh, that's possible. I didn't go that far in my thinkery. Anybody know off the top of their heads what the GOP structure is for H.264? I know for NTSC 1080 HDV it's 15 frames, and for 720 HDV it's 12 frames, but I dunno what the Canons are putting out. A minute spent googling didn't turn up anything definitive.

For those playing the home version of our game, a GOP is the fundamental unit in most MPEG-2 and H.264 data streams. Whereas some formats (like uncompressed, or ProRes) treat a frame or field-pair as a discrete chunk of data, other formats like MPEG-2 and H.264 compress whole sequences of frames as a block. These blocks are called GOPs, for "groups of pictures." If you've ever seen a piece of compressed video go all green and blocky for a fraction of a second, you're seeing an incompletely decoded GOP.

I think Derek may have nailed it. If I copy the current sequence to a new project, and close the old project, everything behaves correctly in the new project.

Since FCP keeps everything in one project file, the problem would be at the project level rather than at the bin level, right? So does it follow that there should be no danger in now migrating all the bins from the old project to the new one?

Strypes asked earlier what format this is. It's Prores 422 1920x1080 23.98, transcoded outside of FCP from RED files. But again, no problems until today, and I've been using all this media for weeks.

Thanks for everyone's help.

Okay, so I was way off the mark on that one.

It's true that Final Cut project files are big blobs that contain all your bins together, but I've never done much debugging to figure out exactly what aspects of them can get screwed up and which are relatively immune. I think my first thing to try in your situation ? purely because it's a real quick test ? would be to export an XML of my project. Load it back up, let Final Cut create a new project out of it and see how it behaves. The simple act of serializing out your project to XML and then back in might be sufficient to clear up whatever's being wonky.

>Anybody know off the top of their heads what the GOP structure is for H.264?

Can't remember too much about it, but I remember it was more complicated than that. Instead of a straight diagram with I, B and P frames, H.264 was like a web with B, P slices and other stuff, with multiple reference frames. And I don't think H.264 does fixed GOP lengths. I could be wrong about this, though.



www.strypesinpost.com

Oh, outstanding. I wish Apple would release an immediate point update to versions 6 and 7 that just totally disables H.264 support in the application, and forces editors to run all H.264 media through log-and-transfer. There would be much wailing and gnashing of teeth, but seriously guys, it's for your own good.

Mumble grumble old man angst.

> Since FCP keeps everything in one project file, the problem would be at the project level rather
> than at the bin level, right?

Yep. Hence the tests I suggested. Still keep an eye out, though -- we haven't nailed it 100 per cent. Clips could behave fine now and crop up with problems later. We've ascertained that the problem is project-specific, but we haven't ascertained that it's not something in the clips that's causing the project file to become corrupt, or the software's handling of the project file. This is telling:

> no problems until today, and I've been using all this media for weeks.

Had you used the specific clips with the problems before this? Same batch of media can still behave differently.


www.derekmok.com