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Old 21st May 2020, 18:28   #763  |  Link
Perenista
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Join Date: Oct 2013
Posts: 205
I noticed what appears to be an issue with MKVToolnix, or with what I have in mind...

I have an ISO (DVD) from a TV recording. When I use MPC-HC to open the DVD, the disc is able to play the 2 parts together. When I use MAKEMKV it generates 2 Matroskas. That's OK, but when I append the 2nd file to the 1st, there is an audio bug that is never seen (heard) in these individual files. So this must be a) MKVToolnix's doing, or b) a bug inherent to this idea of appending. Important: I noticed with other disc that is totally different, so this isn't an isolated case, it's valid for ALL appendings we ever do.

Let's see if I can explain this...

We will assume each video has 2 minutes. Appending would make a single 4 minute MKV file, right?

The problem is that the 4 minute file mutes the audio for a second after the point in which they are joined together.

Like this:

>>>>>> 4 minute file when analyzed further:

2 minutes 2 minutes
====== =/====

/ = the muting.

/ would be at 2:02 or 2:03.

Then at 2:04 the video and audio continue just fine.

But (and here's the catch) if we open file2.mkv and play it... we never notice the / I just mentioned above.

Here's proof of what happened. Instead of just posting a written explanation, I have actually recorded the bug happening

First, I want to show how I am putting these files together:

https://i.imgur.com/1QQDF2s.png

Second, download this file from Google Drive and play in your PC:

-LINK REMOVED-, problem solved

PROOF.mpg;

Pay attention of what happens in the following moments:

- 0:00 until 20 seconds - file1.mkv is played.
- 20 seconds until 47: file2.mkv is played

- Starting at 50 seconds I play this "4 minute" file, which is file1.mkv and file2.mkv appended.

1 minute and 7 seconds: exactly the moment in which the / (bug) can be noticed: the audio is briefly muted. This would be in a 4 minute file the moment 2:02 or 2:03, approximately.

Note that file2.mkv at 30 seconds onwards don't show anything wrong. This is how it should have been in the 4 minute file.

In theory the appending of file1.mkv and file2.mkv should generate a 4 minute file spotless. Why is that not happening?

MEDIAINFO from file1.mkv:

https://pastebin.com/1BgabbRa

Last edited by Perenista; 22nd May 2020 at 02:16.
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