Checksum for .m2ts from "Backup" not matching Pavtube's...

[Acfeiln]

So, I wanted to investigate whether there would be differences in doing a full disc backup of the same disc in both Pavtube BDMagic and MakeMKV. I am using the latest version of both programs (Pavtube BDMagic v4.7.0.5359, MakeMKV v1.8.11).

So, long story short, I did a full disc backup (copying folder structure and everything) of Disc 1 of the Korra Book 2 BD. I used Fsum (Frontend v1.5.5.1) to generate both md5 and sha2(512) checksums for the SAME FILE (01062.m2ts, which is the first episode) and got DIFFERENT results.

I did the same thing with Fsum on that file directly from the disc, and got a different result from EITHER rip.

I would think that the encryption has something to do with the difference in the disc and the decrypted file (I checked that box in MakeMKV)...but why are the two copies different? How can I know which one is accurate? What does MakeMKV check against, exactly, when it says it generates checksum files to verify the rip?

If anybody knows what actually goes on in this process and what might produce these differences...or, more importantly, how I can check for some kind of accuracy against the source...I would be very, very grateful for the help.

UPDATE: I demuxed both files using tsMuxeR (v2.6.12) and decided to check the streams themselves...every single one returns different md5/sha2(512), not just the video stream, every single audio one as well.

[Romansh]

Erm, so one rip is decrypted and the other is not?

Otherwise, are the M2TS files the same size (i.e. can you check the byte count for them)?

Also, can you post MediaInfo reports for both (i.e. the same M2TS, one from the Pavtube backup, the other from MakeMKV's backup)?

[Acfeiln]

Sure thing. Both the MakeMKV rip and the Pavtube rip are decrypted. I was saying that maybe running Fsum on the file directly on the disc, that THAT one might have still been encrypted. But both rips are decrypted, and they are indeed the same size.

It won't let me post anything..."board attachment quota has been reached." Sorry, in case you couldn't tell, I'm new here. -.-

UPDATE: So I still can't upload things it seems, but I have verified that the MediaInfo reports for both files are IDENTICAL. However, the checksums generated by Fsum are not. I've never used Fsum except for this purpose...I wonder if it's to do with that?

Another interesting note: I used MKVToolNix (v7.0.0) to remux the .m2ts files into .mkv...and then again used tsMuxeR to get the streams out. The video stream itself from the .mkv also carries a different checksum...so not only are the checksums of the streams from the .m2ts files different, they are also all different from the checksums of the streams from the remuxed .mkv files. Four different checksums for what I would have thought should be the same video stream...

[motimi]

I am definitely not an expert on this subject, or even very tech-savvy at all, but I'm pretty sure the way that each of these programs backs up the Blu-rays is done slightly differently, resulting in different files with different checksums, even though they are all of the same video.

I've used a few different programs (not MakeMKV) to back up DVD ISOs and I've noticed that the resulting ISOs are different even when I'm only working with one source DVD. I'd imagine that something similar is happening with software that back up BDs.

BTW, if you want to upload an image, try Imgur. For long lines of text, try Pastebin.

[mike admin]

You should get exactly the same checksums for all (non-BD+) M2TS files. Moreover MakeMKV checks the SHA1 hashes of M2TS during backup and reports if they don't match ones stored on disc.