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Old 23rd July 2018, 15:46   #1  |  Link
MaximRecoil
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MKV file is almost twice as big as the source ISO image

The DVD ISO is 3.68 GB, and consists of 8 titles: the main title which is about an hour and a half long and then the rest of the titles are each about 10-15 minutes long (with the last title being about a minute long).

I used MakeMKV which spit out 8 MKV files (nothing was re-encoded of course; it was just repackaging the MPEG-2 and AC-3 streams from the DVD ISO into MKV containers). The file size of the main title alone is 3.6 GB, almost as big as the entire ISO. The combined file size of all 8 files is 7.07 GB.

How is it possible for 7+ GB worth of MPEG-2/AC-3 streams to fit into a 3.68 GB ISO?



I thought that maybe the ISO was somehow compressed, but that didn't seem likely because the video files are already highly compressed (MPEG-2 and AC-3 compression), and I don't see how general-purpose lossless compression could compress them much more. But as a test, I zipped the 8 MKV files, and like I expected, the file size was only reduced slightly, i.e., from 7.07 GB to 6.97 GB.
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Old 23rd July 2018, 16:13   #2  |  Link
sneaker_ger
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Is the DVD using seamless branching or something? (i.e. do the very same scenes of the DVD appear in more than one mkv file?)
https://www.makemkv.com/forum2/viewtopic.php?f=1&t=917
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Old 23rd July 2018, 16:19   #3  |  Link
MaximRecoil
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Quote:
Originally Posted by sneaker_ger View Post
Is the DVD using seamless branching or something? (i.e. do the very same scenes of the DVD appear in more than one mkv file?)
https://www.makemkv.com/forum2/viewtopic.php?f=1&t=917
No. All of the titles have 100% unique content, nothing is repeated. Seamless branching wouldn't have any application for this particular DVD.
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Old 23rd July 2018, 16:35   #4  |  Link
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It would have definitely helped us if you have posted the structure of the DVD instead of stories and assumptions and useless tests.
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Old 23rd July 2018, 17:08   #5  |  Link
MaximRecoil
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Originally Posted by Ghitulescu View Post
It would have definitely helped us if you have posted the structure of the DVD instead of stories and assumptions and useless tests.
I posted no "stories", no "assumptions", and the test was not "useless" (it established that a compressed ISO can't be the explanation). So that part of your post is a non sequitur.

As for the "DVD structure", I don't know what you're referring to exactly. If you mean the file/folder structure as it appears in Windows Explorer, then there's nothing unusual about it. It consists of an AUDIO_TS (empty, as usual) and a VIDEO_TS folder. The VIDEO_TS folder contains 5 VOB files (VTS_01_0.VOB through VTS_01_4.VOB), plus 2 BUP and 2 IFO files. Total file size of those 9 files is 3.68 GB, same as the size of the ISO.



If you open the IFOs in e.g., IfoEdit, there's tons of information, though I don't know which, if any of it, is relevant.

Edited to add: I opened the ISO in DVD Shrink, and under the default "Full Disc" mode, it looks like this:



It shows Titles 1-8 under "Main Movie", the combined duration of them (02:49.26), and the file size is only 3,764 MB. If I scroll through the preview window all of the titles are there back to back. That would fit comfortably on a single-layer DVD.

On the other hand, if I switch to "Re-author" mode, it looks like this:



Now just the main title, duration of 01:26.35, is 3,764 MB, and if I add all 8 titles to the compilation it comes to 7,381 MB, which of course would require a double-layer DVD:


Last edited by MaximRecoil; 23rd July 2018 at 17:36.
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Old 23rd July 2018, 17:47   #6  |  Link
Zetti
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I think Title00 i a combination of Title 01+02+03+04+05+06+07

Because i have some discs there is authored that way.
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Old 23rd July 2018, 17:58   #7  |  Link
MaximRecoil
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I think Title00 i a combination of Title 01+02+03+04+05+06+07

Because i have some discs there is authored that way.
No, title00.mkv is only the main title, which is about 1 hour and 26 minutes long. The combined duration of all 8 titles is about 2 hours and 49 minutes. Every one of those MKV files has entirely unique content; they all correspond perfectly with the 8 titles that are selectable from the DVD menu if you mount the ISO and open it in DVD player software. However, those 8 videos in the DVD ISO only take up about half the disc space of the same 8 videos in separate form, which is the mystery.
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Old 23rd July 2018, 18:29   #8  |  Link
Zetti
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That sounds strange
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Old 24th July 2018, 11:12   #9  |  Link
Ghitulescu
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Something like these





You may think what you want about your completnmess of the posting, yet it appears to be clear from the first image of yours (I'll repeat it below), that you have duplicated content, all titles being in the same VTS.


I have again to assume that you haven't actually checked the content of the MKV files per se or againt the corrsponding DVD titles. I think you have only checked the DVD content, but not in full.

My assumption is that you have 6 main short movies that are also grouped as PlayAll plus some intermediary (transition) scenes. A short look in the menus would have cleared this for good. Typically anime disc.
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