Magic Lantern Forum

Using Magic Lantern => Raw Video => Topic started by: Dardo on March 27, 2023, 11:22:23 PM

Title: File got corrupted because camera shut off. Can it be recovered?
Post by: Dardo on March 27, 2023, 11:22:23 PM
I was recording an interview when at 3/4 of the way when my EOS M ran out of battery. I thought this was no big deal, but then then I found out that the first clip (longest, most important one) is 0 KB big and, of course, can't be loaded into MLV App. Someone told me that the footage may still be there and I might just be missing the header for the file, but since they don't know that much about ML they redirected me here.

So, any ideas? I'm using Danne's latest experimental build, uploaded in January. Thanks in advance.

Screenshots (hosted online because I don't know how to upload images yet): https://postimg.cc/gallery/VttCjSF
Title: Re: File got corrupted because camera shut off. Can it be recovered?
Post by: Walter Schulz on March 28, 2023, 06:18:55 AM
To clarify:
You wrote "first clip". Did you use the same card *after* battery breakdown for any other recording/picture?
Title: Re: File got corrupted because camera shut off. Can it be recovered?
Post by: Dardo on March 28, 2023, 06:14:59 PM
Yes, I continued recording the rest of the interview with the same camera because I had more than 300 GB of free space left. The only change I made to the camera was changing the battery.
Title: Re: File got corrupted because camera shut off. Can it be recovered?
Post by: Walter Schulz on March 28, 2023, 07:08:38 PM
Recovery may be possible if
- Cam stops recording hard because card storage is filled to the brim.
- Cam stops recording hard for whatever reason and no further write operation has taken place.

If file is not closed properly by camera (as in your case) card controller and cam firmware may use anything that looks like card space not allocated. Including said file data anywhere on the card.
So: Maybe some pieces may be recoverable. Some (all/most?) will be lost. Sorry!

But please take a second opinion from people more knowledgeable about how SDcard controllers work. Maybe card controller has indeed used diferent storage cells. Controllers do load distribution to balance write cycles for storage cells. I cannot tell to what extent.


Title: Re: File got corrupted because camera shut off. Can it be recovered?
Post by: names_are_hard on March 28, 2023, 09:47:43 PM
What's the current reported free space on the drive?  You definitely won't recover more than that amount from the missing file.

The first thing to do is image the card.  That way you're working from a single file on a fast disk, and you don't need to worry about changing the card and maybe losing more data.

When you've done that, use photorec on the image file.  Maybe you'll get lucky.
Title: Re: File got corrupted because camera shut off. Can it be recovered?
Post by: Dardo on March 28, 2023, 11:24:39 PM
Thanks guys, seems like I'm simply screwed. I'll have to search what Imaging the card is, like names_are_hard said, but I guess I'll just do the editing and scripting with the audio (I used a recorder for that) and then ask the guy to repeat only the interesting parts. I hope he's up for it.