I have been backing up my photos (jpegs) and music files (mp3's) for some time now and have been meaning to ask:-
I have "do not compress" selected, but the files are still placed within zip files by the AISBackup process. Would the quality of the files deteriorate if I had to do multiple restore & backups (i.e would compression of some sort kick in each time)? Would this differ (e.g. be worse, I imagine) if I had compression selected?
Thanks a lot
Jim
Compression / Quality
Compression vs. No Compresssion
Hi
The files are not compressed within the zip files but information about each file is stored along with a list of all files in the zip file, called the central directory. In fact no compression means the backup is slightly bigger than the original data.
There is not much performance difference between compressed and uncompressed up to version 1.8 but from version 1.9 AISBackup backs up and tests a backup a lot quicker when using uncompressed.
The files are held within zip files to enable AISBackup to function correctly. If you would prefer an exact copy of the original files use the Tools / Disk to Disk Copy option instead.
After re-reading your question I think I should also mention that the zip file format is a loss-less compression technique, in other words there absolutely is no way that the original files can deteriorate within a zip file.
Barry
The files are not compressed within the zip files but information about each file is stored along with a list of all files in the zip file, called the central directory. In fact no compression means the backup is slightly bigger than the original data.
There is not much performance difference between compressed and uncompressed up to version 1.8 but from version 1.9 AISBackup backs up and tests a backup a lot quicker when using uncompressed.
The files are held within zip files to enable AISBackup to function correctly. If you would prefer an exact copy of the original files use the Tools / Disk to Disk Copy option instead.
After re-reading your question I think I should also mention that the zip file format is a loss-less compression technique, in other words there absolutely is no way that the original files can deteriorate within a zip file.
Barry
Compression / Quality
Thanks Barry - I had not realised that the zip format was lossless compression, which really answers my question from all angles!
I think I must have been thinking of the jpeg process - which can degrade an image each time a picture is re-saved.
Jim[/quote]
I think I must have been thinking of the jpeg process - which can degrade an image each time a picture is re-saved.
Jim[/quote]