Using SyncBackPro > Expert Mode > Compression, Compressed

To increase compression performance SyncBackPro can be configured not to waste time trying to compress already compressed files, e.g. MP3's, JPG images, etc. Instead of compressing files of these types it will instead store them (without compression) in the Zip file. Note that they are still stored in a Zip file but are not compressed within the Zip file.

•Auto-detect files that may not compress: If enabled, SyncBackPro will check if a file can be compressed before compressing it. File types in the filter are ignored as those will not be compressed anyway. However, by enabling this option you can avoid trying to compress files that cannot be compressed. To check for compressibility, SyncBackPro will quickly compress 1MB of data from the middle of a file. This is done in-memory and using a low compression level. If that data cannot be compressed by more than 5% then the file is considered to already be compressed or the compression rate is so low it is not worth trying to compress the file. It is important to note that it is impossible to know if a file can be compressed or not unless you actually compress it using the compression method and levels chosen. Therefore, this method of checking for compressibility is not fool proof.

This profile settings page can use and create shared settings.

To add a file type (not to be compressed, but just stored) click the Add button. You can then enter the file type, e.g. JPG. There is no need to prefix it with a period (.) as it will be added automatically.

To remove a file type, select it in the window then click the Remove button. While selecting, you can use the SHIFT and CTRL keys to make multiple selections.

If a file is stored, and not compressed, the variables %STOREDEXTTOTAL% and %STOREDCOMPTOTAL% are incremented. The log file will also state the total number of files that were not compressed.