www.makemkv.com

Hi I am wondering I have Scream UHD movie normally i use different software to back up my full iso and the full disk should be 59 GB but Make MKV backup is 58 GB what is lost? my normal backups match size
My asus drive could not read the disk but my pioneer would which the other software is not compatible with

Ok i did some more tests i bought a second copy of Scream 1 and was able to make a new copy using the other software to make an ISO and then remade a backup with the new disc and it was the same here is The MTS Comparison it has lost some bitrate compared to the backup iso image The Lower bitrate is from the Makemkv folder
and here is the BDinfo Scan of the Backup folder And ISO File so any reason to this by chance? hopefully someone knows thanks again

I guess my main Question is shouldn't the mts file be the same as the original and both comparisons are decrypted when making backup to folder option?

I don't normally use ISO files, so I'm just speculating. However, as I understand it, an ISO file is a disk image that includes everything that would go on an optical disc, including the file system overhead. Blu-rays use the UDF file system, usually version 2.5. I don't know what the overhead is for UDF, but it is not zero.

When you use MakeMKV to create a .mkv file or a backup of the whole disc, it does not contain any UDF overhead.

I would guess this filesystem overhead accounts for the different in size between an ISO of a disc and a MakeMKV backup.

A bit more info would be helpful, primarily what software you used to do the full iso backup, and then what software you used to get the video files out of the iso. Needless to say MakeMKV is not even capable of compressing the video data as it's being ripped, and even more certainly not when doing a full disc backup. To confirm this, use MediaInfo to check the actual bitrates of the video and audio tracks within the .m2ts files. This will also tell you the number of tracks and list every single one, here might lie the discrepancy between files? Perhaps some additional tracks only useful for encryption is tossed out by MakeMKV's particular decrypted-disc-dump process? Keeping in mind that all implementations of creating a "decrypted disc dump" are inherently proprietary to every piece of software that can do it, as they all are changing the data in some way as it passes through - y'know, to decrypt it - and they have to choose what data to remove/modify and how to best do it.

I would then also be curious, if you did an encrypted backup of the same disc using your two different solutions, would you get files with exactly identical sizes? Since in that case neither MakeMKV or your other mystery software are doing any on-the-fly modifications to the data?