Comic Book RAR (CBR) converter

A CBR file is a RAR archive of page images, the same idea as CBZ with a different container. RAR was popular with comic scanners in the early 2000s because it compressed slightly better and could split large files into parts, so most older scans circulate as CBR. RAR is a proprietary format: RARLAB's free unRAR code may be used to read archives but not to create them, which is why many tools open CBR files and almost none write them.

Two generations are in use. RAR4 archives start with the bytes 52 61 72 21 1A 07 00 and RAR5 archives, written by WinRAR 5 and later, with 52 61 72 21 1A 07 01 00. Both open here, including solid RAR5 archives. Extensions are unreliable in practice: plenty of .cbr files are ZIPs and plenty of .cbz files are RARs, so we look at the signature and treat the file as what it is.

Encrypted archives and split sets are the cases we cannot handle. A password-protected RAR cannot be read without the password, and the first file of a .part1.rar set only contains part of the pages. Both are refused with a message rather than turned into a comic with missing or blank pages.

The most useful conversions are CBR to CBZ, which repacks the same images byte for byte into a ZIP every reader understands, and CBR to PDF for devices without a comic app. CBZ to CBR is not offered, since writing RAR needs RARLAB's licensed tool and gives readers nothing a CBZ does not.