Frame Errors *only* when viewing at 100% Resolution

[Nimish Thapar]

Hey guys. Got a bit of an odd thing here. I'm getting a frame read error from one of my clips, but ONLY when I'm looking at it 100% (I've attatched an image of what the error looks like) However, once I scale to 50% in any program I'm working in, the error is completely absent. Does anyone wanna let me know why it's only coming in at 100, and what I can do about it? This is test footage as it is so it's not like I lost anything crucial, but I'm still curious as to why it's happening. And I checked the original clip on the card, same issue at the same frame so it wasn't a dump error. Anyone got any thoughts? Or advice to avoid in the future? (Or most dreaded, do I have to send my Scarlet back in?)

 

[Terry VerHaar]

Questions that come to mind... what hardware set-up? GPU? Is this from RCX? Have you looked at it in an NLE or Resolve? What were the specifics of the footage?

You could open a ticket with RED and send a log if you want to get ahead of the problem - in case you can't figure it out.

 

[Nick Pasquariello]

The way Red files are written, they write the first, say, 32nd of the image first (literally every 32nd pixel), then once that's done for the whole image, the file writes in every 16th pixel, then every 8th, then every 4th, then every 2nd, and then the remaining. That is an oversimplification that is MUCH better explained here: http://www.red.com/learn/red-101/redcode-file-format

But basically, when you cut the resolution by half, you aren't taking the frame, then processing it, then squishing it down. You are LITERALLY grabbing every other pixel, and ignoring the rest. [This is actually REALLY clever in terms of the bottlenecks we run into in computers. You don't need as much bandwidth between your storage and your processor; you then also cut the processor usage substantially since you are processing so much less data through it. RedCode is a fantastic amazing thing that people don't often give enough credit to.]

Which means that the error that you're seeing is likely because some bit got flipped somewhere in that other half of the pixels that the computer ignores when you're at 1/2 res or lower.

Sometimes the file on the original Magazine is fine, if you haven't written it over yet. If the copy of the file that you're using is the ONLY copy, well, you're likely screwed on that frame . . .

 

[Nimish Thapar]

I'm on a iMac, but I'm nto 100% sure on the other specs as I'm not near that computer right now. How do I send a log to Red. I think a ticket might be a good idea at this point

I've tried to do this in Adobe Premiere, Final Cut, After Effects, and RedCine-X. The screenshot above is from the original magazine, (like I said it's a test shot so if the footage is bad it's not a big deal) but I'm wondering if there's anyway to fix that stray bit?

Also is there any way to produce a red intermediate at say, half resolution, just to send back the special effects deliverables? I don't need the 4k footage, as the test is being delivered at 720p. I haven't checked in camera, as it may just be my computer not being able to process the R3D, but I think it's the file at full res.

 

[Nick Pasquariello]

If you render out the clip with a Half-Res Debayer, you shouldn't have the problem in the output file. If you do a Full Debayer and then downres, you probably will see it. Why? See my post above.

If this is for a test though, I wouldn't be too worried. This kind of error can indicate one of two things:

1. This is a fluke and you probably won't see it again for a while, if ever.
2. There is an issue with the camera or magazine.

Talk to Red. They'll ask you to send in a log file from the camera (and they should tell you how to do so).

 

[Nimish Thapar]

Alright. I'll try the half debayer method. One question, since I'm still sorta a noob with red cameras... How do you do that? Also yeah I'll probably just keep an eye out for this problem in future shoots but I feel like I'll send in a log to red regardless. Thanks for your help nick!

 

[Nick Pasquariello]

When you set up your export settings in RedCine-X, you have the option to select the level of Debayer; when you are looking at a 1/2 res of the file, that is a Half Debayer. If you are looking at a 1/4 res, that is a Quarter Debayer.

In RedCine-X, at the bottom, there are a bunch of tabs. One of them is Export. From there, hit the + sign in order to create a new Export preset. You get a ton of options, can choose whatever type of file that you want. Right on the first page is a button that says Debayer Settings. Set them to 1/2. Set everything else a you want. Save the preset.

Then you can use the preset to export whatever clips you want.


Now, if you are using an editing program that utilizes raw R3Ds, you might not find yourself in RedCine-X that much. Being able to really use the raw files throughout editorial is a relatively new thing. You can probably export the clip at 1/2 res (1/2 Debayer) in those programs as well, but I know the steps to do so in RedCine-X by heart, so there you go. How to do so in the various editing programs, I don't have memorized.

 

[Nimish Thapar]

Haha that's perfectly alright. I can clone the look into the debayer from redcine-x and pull that into adobe after effects. Thanks again for your help! It definitly saved the test, and here's to hoping I don't have to send my scarlet back in to LA.

 

[Tim Bradley]

I know you said its not a dump error, but I have had exactly the same looking frame errors that were a dump error or computer induced error. When I checked the SSD on another computer all was fine, so my suggestion is to try looking at the footage on another computer.
I have a MBP that just does not work with R3D files without giving me this same error.

 

[Tim Bradley]

The image attached above shows a reasonably bad corruption issue but the problem ranged (for Me) from almost un-noticeable to completely corrupted.

Since changing laptops I have never had the issue again. I had sent my camera twice to Red prior to changing laptops. The Red techs both times could in my case find no issues with my Epic.

 

[Nimish Thapar]

I'll definitely try that out. My hope is that this is an in-house fixable problem. I should also check that computer because it was acting up and seriously slowing down while exporting the clip/ wrking with it so it might just be the computer.

 

[Nimish Thapar]

Well Tim it seems that the problem persists between computers. I've opened a ticket with Red. I guess It'd only be appropriate for me to keep you all in the loop so I'll let you know what they tell me.

 

[Tim Bradley]

Well Tim it seems that the problem persists between computers. I've opened a ticket with Red. I guess It'd only be appropriate for me to keep you all in the loop so I'll let you know what they tell me.

Bugger. It was worth a try

 

[Nick Pasquariello]

My best-educated-guess is that you are both having the same problem, but it's happening in different places. For Nimish, the problem is in the raw data of the file. For Tim, the file gets interpreted, and something is getting calculated wrong in the CPU or GPU. Since Tim's problems are only happening in one computer, and since they are localized only to Red files and in various pieces of software, then to me this points to a single transistor in the CPU or GPU that just ain't right. [The newer style of MacBook Pro, when it first came out, had an issue in the NVidia chips, where the specific metals used would crack over time. It was a faulty NVidia thing, not an Apple thing, but this is a real world example of the kind of thing that could cause what you saw, or worse.]

In either case, the image is drawn out "in sequence". Meaning that if a single bit gets skipped, added, or flipped, it doesn't just affect the one pixel that it happened on. It affects every other pixel in a line after it. Because in all these scenarios, each Pixel isn't recorded, bit for bit. The data is looked at as a whole, and compressed down, and then later decompressed and interpreted for viewing. Why compressed? Because storage is finite. Most video formats work this way (except for the appropriately titled "Uncompressed" format) and why DIT's are so adamant about using checksumming software on set. The chances of anything happening to any particular file are, I'd say, 1 in 10,000 (though it can subjectively feel like 1 in 100).

But I plan on sorting through more than 10,000 files in my career. The chances of two different files resulting in the same MD5 hash are, well, low enough that if it happens to me, I'll chalk it up to fate not wanting me to work with that client again.

 

[Nimish Thapar]

Sounds like a pretty good description Nick. So far Red seems to think it's a one off glitch, (their engineer's are currently reviewing my log file). I am happy enough that it only happened on test footage to be honest, as this way I lost nothing crucial.
I also realised I'm not operating on the latest Firmware (I missed a few updated while travelling) so it may simply be something Red is aware of and they already addressed. I'll let people know what happened. But in any case thanks for all the help you guys have provided, and in keeping me from freaking out. Granted I don't have any projects for another month so if I did have to send my red in for repairs I wouldn't be too out of it, but here's fingers' crossed hoping it's a one time fluke.

 

[Nimish Thapar]

Well it seems I overreacted to a one-time fluke. Nothing wrong as far as Red can see (internal sigh of relief). Thanks for listening and helping me out guys. And once again thank's for the debayer save for the one clip.

 

[ericyoung]

Shoot lots of test footage interiors, exteriors, in different heat conditions, running for several hours continuously, now while you have the time. Try to stress the camera - if it holds up with no more critical errors you'll have much more confidence. If it fails, at least you can get it fixed before a paying job!

 

[Nimish Thapar]

I do still have a full two hours of screen tests tomorrow so I will be just scrutinising all that footage like crazy. My next paid project isn't slated until june so I should be good either way. How long do red turnarounds usually take?

 

[ericyoung]

I do still have a full two hours of screen tests tomorrow so I will be just scrutinising all that footage like crazy. My next paid project isn't slated until june so I should be good either way. How long do red turnarounds usually take?

Depends where you are relative to the nearest Red repair centre, and what the fault is!

 

[Nimish Thapar]

Haha I'm across the country in the Northeast. But here's to hoping my tests tomorrow all come just fine.