Fixing corrupt MLVs - A shoddy story & what? where? how?

[user0597]

This will be a long read, however, hopefully an entertaining scribbling of idiocy and desperate quiet anger. Enjoy.

So, a couple of Sundays ago, before nerve wrecking and data restoration, I was shooting on a pond. As it's customary while shooting raw, we ran out of card space just when we didn't have time to spend. Only time to take the card and transfer about 2-3 files off the card to get a couple of takes in and then drive one of the actors where he wanted to.
Laptop open, card in, Ctrl-X and Ctrl-V. Going, going. Not. Not going. Frozen to a snail's pace at 44 bits per second. No good. Spent 3 of the 5 minutes I had for this already. Maybe the card is too full – delete the .tmp file. Going. Going. No. Stiff as a board. That's fine, happens. Unplug, redo, delete. Bing, bang, boom, out and shoot two more takes. Looking good.
Take the actor home, swing by the house to unload the MLVs over a USB3 connection before heading back for the last shots of the scene.
Plug in, card full – great, select the files and.... hold on. Select the files again. What's this? Properties. 29 GB? Out of 59GB? *alarms seeping in and out through the veins in my eyes*  Copy all that's there off the card. Open. No. No, only a couple of them work. Something's way, way, way the hell off. Can't touch the card now. Scrap all other plans. Get the gear from the woods and get to the bottom of this.
Sit down, form a plan. Raw dump of the bits using ,,HDD Raw Copy Tool" (didn't work, later on rewriting it to the card was only greeted with an access error).
Run chkdsk to repair the file system (was able to get 29 out of probably 32 files out, 90% with conversion preventing damage). Folders FOUND.000 and FOUND.001, you magnificent bastards.

Do they start? No. Convert? No. Do they have size to them? Yes. So... I could have the files or... I could have a bunch of fancy shredded paper. No clue at this point and no experience that could soothe my nerves in any direction.
Some kind of data copied, a raw copy of the entire card as a fallback, time to break out every kind of partition/card/HDD data rescue program you can get your hands on through the internet.
Nothin'. Fancy didn't work. Break out the CLI. Testdisk stumped. Photorec stumped. Fine, the card doesn't want it, I don't want it either then. Let's see about the rescued files. Maybe some hope of salvaging any kind of mood out of it... or complete and utter realization of the start of things tirelessly going wrong that week.
Where to start? Someone must have at least had something similar happen, right? Or has it? A post on the Magic Lantern forum about damaged headers, HEX values mentioned. So HEX is the key? Hex it is. Open up the file. What? No words to even find. Absolutely no experience with the structure of the MLV files, what constitutes a block even? Magic Lantern forums. Someone mentions MLV_Dump.

For the sake of sanity, let's skip the chapters of the learning process and proceed all the way to the getting things back on track day. HxD the tool of choice. Some files – headers gone. Other files – damaged frame(s) with VIDF blocks needing replacement. Metadata in some places, metadata....not...in other similar blocks.  Handicraft and test runs through MLV_Dump.exe to work my way through. A third of the previously dead files have frames with visual glitches here and there, but a tremendously larger amount of files saved in total than hoped. Brilliant. Almost everything there. Moments that won't be lost like bits on a broken disc. It's late, better finish tomorrow... *a dark cloud peaks afar* you've earned it...
Morning. Let's go. Boot. Get the external drive. Alright. It's taking a minute. It's always been slow. Taking a while, though. Replug. Yes, this is it. Should work. Taking a bit, though. Re-do. It's not doing it. The *censored* drive I just put hand*censored*fixed *censored* files on! Come on... at least enough to catch my breath. Noup, does not comply. Fine, shred the damn external case. Hook up to PC direct. No. No, it won't work. With all other projects on it that have no back ups, better not force it before making a raw dump first.

Skip the scarping together of money and purchasing a drive and a successful recovery two days later.

Got it all, let's get things on track. Get the camera, format, test. Nice. Restart. Format.... hang on. Redo. No, no... Plug in to PC, format, replug: ,,This card needs to be formatted before use"
*cue head meets desk* ...a break.  I mean, I'll take anything at this point. Just please can I not get hit by lightning on Friday at this rate?
Card? No good. Cannot hold any kind of format by any tool known to man. Tried them. As soon as you reinsert the card or cycle the camera the thing is jumbled. HEX looks like a wheel-of-disorder all over. No matter what your wrote before. Effectively dead. Only Lexar itself can help now. And they are. It'll be swapped.

What should have been a day of shooting took two weeks to sort out in total. Moral of the story? I don't know if there is one. Don't hurry perhaps. Especially when you have to. It only changes it from a chance to a probability.
I wrote a guide for my own personal use in case I should ever need to repair a MLV again. Hopefully it'll be under a thick stack of digital dust in the future.

The way I went about fixing the MLVs, written by someone who has approximate knowledge about many things... so assume nothing:

Edit: Updated the guide to a much better version.

[dogmydog]

Dude, thank you so much for this!
I shot a commercial video on my 50D and the camera stopped recording, so I had to restart it.
Now the MLVRAWVIEWER wouldn't open it, so I edited the HEX file and copied the header from another working file and it worked!
Thanks and many cheers,

[Kharak]

nice read!

I know that feeling, when ones eyes start pumping out of your face and the blood in your feet is leaving and that thought in the back of your mind comes crawling.."You are fucked!"

Luckily, ML never failed me that bad, always was able to recover what ever I "lost".

And thanks for the guide, I'll be sure to save it a special place in case I get as deep in broken MLV's as you did.