|
Camcorder Recovery
|   |
|
Camcorder Recovery
| |
Mini DVDs are typically used in Camcorders, Video cameras etc. The typical failure mode is related to sessions not closing, or just general failure at the start of disk.
Different types of camera do use slightly different logical recording methods, but fortunately, the basic standard is to record mpeg files, with some control files, IFO files. It is very common for a failed DVD not to have any of these IFO files, but recovery is still possible.
There are three possible ways to work on a Mini DVD that has failed
A mini DVD is normally recorded as an ISO9660 structure, or UDF with groups of files with the following extensions, IFO, BUP and VOB. The
file IFO and BUP are identical. The VOB file stores the mpeg data and therefore is the important one to recover.
A VOB file is basically an MPEG file with addition information taken from the IFO and BUP files. The maximum size for a VOB is 1GB, and so on a long movie there will be multiple VOBs and matching IFO files. In addition there should also be a VIDEO_TS.IFO and VIDEO_TS.BUP, with an optional VIDEO_TS.VOB if there is a start menu. If it is possible to recover all of these files, then a new video disk can be created. If only the MPEG can be recovered, it is necessary to rebuild the IFO / BUP files. This is performed by a feature (currently under development) to rebuild video files
Wizard recovery
For many camcorder disks, they will be detected by the wizard as Corrupted Video Disks. If the screen indicates that several files are present, then a full recovery may work. Typically, it will be necessary to recover files from unallocated space.
Logical recovery
The Recover function will allow recovery of files in a logical way - as long as the disk has the basic control blocks still intact. If this fails, then Raw recovery will be the best option.
Raw recovery
The raw recovery mode is probably the most common mode for recovery of video disks. It will scan the complete disk, and extract either a single large MPEG file, or many smaller mpegs, based on individual chapters. If the individual chapters are required, then the Separate video file chapters option should be selected. Different camcorders work in different way, so it may be best to try a recovery with 'Separate video file chapters' enabled and disabled.
Raw recovery can be done with a complete scan, but often the start of the disk cannot be read. It is therefore advantageous to determine where the data starts. There are two ways, one is to use view sector, and try different starting points, eg 20000, then 10000 and try and find the start by trial and error. The easier way is to us the built in function, Search for start sector. Once the start location is determined, and the options set (Split on possible file starts and Separate video file chapters) then a scan can be performed.
If after a period of time the scan moves very slowly, and comes up with a significant number of errors, the scan can be cancelled, and the reconstruction started.
MPEG reconstruction
If the raw recovery mode described above has been used, then the files will be a series of MPEG files. These can be double clicked and viewed Windows Media Player. However, they can not be written to a new DVD and played on a domestic video recorder. There are several options. There are many applications that can be used to create Video disks from MPEG files, and often such features are built into DVD burning programs such as Cyberlink Power Producer - 2 Gold. The CnW Rebuild video files (when complete) will allow mpegs to be merged, and a video disk image recreated.