Files with SIB extension are created by Sibelius application. SIB files contains a sheet music document. Music notation can be created using MIDI devices or other software tools.
After converting the file to the new format, you will be able to use other programs to support it. Keep in mind, however, that the S7 file after converting to SIB may differ slightly from the original. The most important information should be kept, but if you want the file after conversion from S7 to SIB to be the same, you have to do this carefully and choose the proper application from the list below.
There is no guarantee, of course, that the conversion will come up to all your expectations, but it will certainly help you. If, after all, the effect of converting S7 to SIB does not meet your expectations, you can simply try to find on the Internet a different version of your file in S7 format, properly converted to a SIB file by someone else. If this fails, use the information provided in the further part of the website.
Unfortunately, if after performing the two previously described steps (trying to find your S7 file converted by someone else, and the attempt to convert it to SIB on your own) you still have a problem with your file, then there are only a few solutions left. You can once again try to find and install an application that can open the S7 file in its original format (without conversion to SIB file). Such a solution will be difficult to implement, but it certainly will give the best result.