Card vs Disk Recovery
SD card versis Hard disk recovery

Data recovery is data recovery - well sort of!

In reality, recovery from a camera memory chip is much harder than from a hard disk drive. There are two main reasons for this, the type of file system, and the fact that a memory card file is almost certainly fragmented.

Most PCs use NTFS as a file system. When a file is deleted, the directory entry is marked as deleted, and the sectors used are freed for future use. As long as nothing overwrites these two areas, a full recovery is possible. Typically, on a PC hard drive, the files are sequential. This means once the start has been found, the rest just follows on. Unless the video has been edited, or the disk very full, a quick and easy recovery is possible. A MAC disk is not quite so easy, but again typically, files are sequential. This finding a file start, will typically yeild a good working file, even if the file name is missing. Many programs do this - and is often called Data carving.

When it comes to memory chips the story is rather different. Very few video files are sequential - most have at least two fragments,. and a GoPro can have maybe 1,500 fragments. The next problem on a memory chip is that most are FAT32, or exFAT. When a chip if formatted, or files deleted, it is normal for the location of each fragment to be lost. Sometimes this information does remain on exFAT chip, but for a FAT32, it is always lost. The solution to find the file start (easy) and then assume the file is continuous, just does not work. This is why most data recovery programs fail. GPR on the other hand does a complete memory chip scan, and then joins the hundreds of fragments together. This a complex, and sometimes rather slow procedure, but ensures that valid file is recovered from memory card.