Hello there,
Long story short: I have a big PC game collection from golden era (1995 - 2010) - digital ISOs and BINs and a limited space to preserve them. I dont trust clouds in any form, so I prefer old school external HDDs for store. For me 7Zip is a good way to archive them and save some space, but recently ive found out that if you convert a BIN or an ISO file to ECM and then you archive it with 7Zip (ultra compression), the final compression file size will be in most cases almost at a half compared to original non ECM file.
Example:
Original Bin file (rld-cl1.bin) - 672MB
Original Bin file zipped with 7zip on ultra compression (rld-cl1.7z) - 268MB
Original Bin file converted to ECM (rld-cl1.bin.ecm) - 586MB
Original Bin file converted to ECM zipped with 7zip on ultra compression (rld-cl1.bin.7z) - 195MB
So there is a difference of 73MB in this case.
Does this method is good? You can damage the BINs in any way if you ECM them, ZIP them, unzip them and UnECM them back to BIN? I noticed in properties of an UnECM(ed) BIN file that the BIN no longer have Last Modified Original Date - in this case was year 2005.
There are other different methods to save space? I dont care much about loading time from archiving/extracting. I just want to be sure that all the files remain untouched in this process. Thanks
Checksums seems to be the same. Around 35% in average, depends on files stored in Bin/ISO image.