Recover videos in damaged disks and cards

For Mac users, I have already covered this topic a few months ago, but now I have a better tool in development that will be ready before Xmas. I will unveil it very soon.

For Windows users, I have recently found a good technique to create a disk image from the damaged disk or card, which is the first step towards recovery of footage.
Note that this can also be useful to Mac users if the disk is not visible in the Finder, but is visible on a Windows PC.

In a nutshell, we use a small utility called dd for Windows that is able to read the raw data of a disk. (From now on, I will just use the word disk, and it can refer to a hard disk, a memory card or a USB drive)

Under the premise that the disk is readable, ie Windows detects it when you plug the disk or insert the card in the reader, “dd for Windows” should be able to create a file with about the size of the disk.

Here is the process, step by step:

1. Download the utility:

http://www.chrysocome.net/downloads/dd-0.5.zip

This program is free and distributed under GPL license. For more information, refer to the product page.

2. Unzip it and make a copy on your Desktop.

3. Connect the damaged disk to the computer. Your PC must detect it, otherwise the technique doesn’t work.

4. Open a DOS shell (ie launch the program called cmd) and type the command:

dd --list

And you will get a list of the devices connected to your computer.
Here is what I get for example:

rawwrite dd for windows version 0.5.
Written by John Newbigin
This program is covered by the GPL. See copying.txt for details
Win32 Available Volume Information
\\.\Volume{aef46cf9-3e3d-11de-b8c6-806d6172696f}\
link to \\?\Device\HarddiskVolume3
fixed media
Mounted on \\.\c:

\\.\Volume{aef46cf8-3e3d-11de-b8c6-806d6172696f}\
link to \\?\Device\CdRom0
CD-ROM
Mounted on \\.\d:

\\.\Volume{6f41f4b2-d11a-11de-b318-001d4f88486c}\
link to \\?\Device\Harddisk1\DP(1)0-0+5
removeable media
Mounted on \\.\f:

Don’t be afraid, it’s just a list of the devices connected to your computer.
Here the interesting device is the F:\ volume described as removeable media: this is the card that I want to recover. Take note of the corresponding volume name:
\\.\Volume{6f41f4b2-d11a-11de-b318-001d4f88486c}

This volume name starting with \\.\Volume{ and ending with } will be used in step #6.

5. Verify that you have enough space available on your hard disk. The rule of the thumb is that a 4GB card will produce a 4GB file, a 120GB hard disk will need 120GB and so on.

6. Type the command below. Of course, you will replace my volume name by the volume name that you have noted from dd –list output:

dd if=\\.\Volume{6f41f4b2-d11a-11de-b318-001d4f88486c} of=c:\usb.img bs=1M

This command creates a file called c:\usb.img that is a carbon-copy of the damaged disk.
The operation can take a long time. For 1GB, it can take one minute or more. For 120GB, it will take several hours.

Note that you can monitor the size of the c:\usb.img file as it grows from 0 to the size of the disk: It will give you an idea of the progress.

What do I do with the .img file?
Now if everything went fine, you should have a .img with a size similar to the disk capacity.
If the disk still contains footage, the footage must now be inside this file also, and we can do a diagnostic of the file and hopefully, repair it.

For Mac users, Diagnostic and Repair have already been covered in a previous post.
For Windows users, the .img file can now be used to create an extract that will be uploaded to Aero Quartet. This is explained in the Movie Repair Guide in the Windows page.