Process fragments

Process fragments and partial files

It is very common in recovery to have areas of the memory chip containing video that is not part of a main file. The could be due to corruption, or partial overwriting. It could also be when a file as not been finalised correctly, maybe due to a camera failure, or a physical 'crash'.

The Forensic only option of 'Process fragments and partial files' will help restore these files to be a usable video. The operation for this is in two stages and is enabled by the option box 'process fragments and partial files'. The standard GPR recover is stages 1-5. These stages will process all fragements and generate files where all elements , ftyp, moov and mdat exist on the memory chip. The saved file sare recover_xxx.mp4 or recover_xxx.lrv

Reconstruct videos
The reconstruct process is stage 6. At this point any time an unused ftyp, and associated mdaa for Hero 4-8, is found, the fragment chain is followed to gnerate a file that may have say 30 fragment runs. After this, a moov atom is generated based on the fragment run found. Obviously this means that certain information such as date is not known.

Generating a fragment run with no origianl metadata can be flawed, so at times a fragement from one video is merged with another. This is an area of on going development to improve the accuracy of the result. The files are names reconstruct_xxx.mp4 or reconstruct_xxx.lrv

Build videos

The build process is stage 7. It is very similar to the reconstruct stage but just starts with a cluster containing video. It does not require any existing atom, (ftyp, moov or mdat). It will then recreate all required atoms. The success rate is reasonable, but not always 100%. The best results are from a camera where the mode settings have not been changed, and with a larger cluster size. Less good results if there have been multiple mode settings, and on a small cluster size memory chip.