This rule allows you to attach a new extension. It is useful when the extension of a file is missing (or if the file has a wrong extension). There is an option to find the correct extension based on the file's structure..
The parameters are as follows:
|New extension||Simply adds the new extension to the file name.
|Append to the original filename||If this option is deselected, the new extension will replace the old extension. (This can be used if the file has a wrong extension, for example.)
If the option is selected, the new extension is just added (This can be used when the file does not have any extension at all).
|Detect using binary signature||Sometimes the extension of a file is missing. At other times it is wrong (e.g. some downloaded files get the aspx extension, although they may actually be zip or pdf.)
One way to identify the file extension is by trial-and-error: Attach different extensions and try to open the file with its associated application. This is very tedious.
A far more efficient way is to compare the file's digital signature with the signatures of known file types and identify the file's type. This is done internally within ReNamer, so you do not have to know what a "digital signature" means, or the actual value of the signature for the given file.
Note that different extensions do not have unique signatures. So sometimes the file's signature may match the signature of several different extensions. In such cases, ReNamer shows the New filename with all matching extensions. For example, "fileName.flv|wmv|pdf". ReNamer also pops up an error window (because the combined extension is invalid). Just read the suggested extensions and then try them out one by one. This method is still better compared to making wild guesses, because ReNamer suggests only 2-3 extensions.
For more accurate results, use ReNamer with TrID, a specialized utility for identifying the file's real extension. Be aware that even TrID often suggests multiple extensions, and you still have to try them out.