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Disclaimer. English is not my native language, so pardon me for possible grammatic mistakes
Part 1.
I got stuck with being unable to use bluray menus in vlc on fresh windows 10.
Here i will describe steps i took to debug and fix libbluray and java compatibility issues.

By reading this thread you will learn:
- how to get debug messages from libbluray
- how to spot compatibility issues
- how to spot and fix dependency issues for dll's

I hope that you will find this guide useful for fixing your problems with vlc.

=============
Currently i found out that combination of:
- vlc 3.0.16 Vetinari (jenkins@acd0bd199cbd Jun 18 2021 16:21:52)
- java jre-8u321-win64
works fine for playing bluray with menus.
You can install this combination and look at part1 and stuff described in part 3.3 of this guide for fixing missing dependencies, in case you've got a fresh install of windows
=============

0. Basic knowledge
libbluray - part of vlc(library) used to play bluray disks, If you have issues with bluray playback, chances are libbluray is at play here.
java\jvm - java is a programming language which requires jvm (java virtual machine) to run programs written on it. In context of this post it is used to display menus of bluray disks (other thing don't concern topic of this post)
jre - package which contains java+jvm and can be installed on your machine
BD-J - standart which describes how to use java for menus on bluray disks

1. Symptoms of the problem
1.1. First error
When opening bluray disc Media->Open Disk->Blu-ray with unchecked button "No disc menus" i've got popup message 1.2. Looking at logs
Open debug messages window Tools->Messages and set "Verbosity=2 (debug)" at the bottom of the Messages window.
Then try to open bluray disck as described above. Error message described above will appear.
Now look at the messages window, here you would find error from libbluray looking like this
2. Debugging libbluray
At this point i found out that the problem lies within libbluray, so the next step will be to get logs directly from libbluray.
Here i did some source code digging to found all the info i need. (i just downloaded sources to my pc, opened them with vscode and started searching for things)
You can get sources from main page https://www.videolan.org/developers/libbluray.html
or look at the git directly https://code.videolan.org/videolan/libbluray

So to get logs i launch vlc from command promt with environment variables, here is how to do it:
2.1. open CMD (just search "cmd" in windows, no admin rights required)
2.2. in cmd navigate to vlc directory, i used following command: *depends on your install path
2.3. set environment variables by typing: This code will set variables for this cmd window only. It means that you should launch vlc from this command promt (as described in p.2.4) otherwise vlc will ignore environment variables.
BD_DEBUG_FILE points to file where libbluray will write logs. I created directory "C:\temp" beforehand, also make sure that diractory doesn't require admin rights to create\write to files.
BD_DEBUG_MASK sets the mask for filtering debug messages. You can find supported values here https://code.videolan.org/videolan/libb ... trol.h#L31
I've decided to don't think about it that much and used value 4294967295 = 2^32-1 so that mask consists of all 1 in binary form and it will pass every message (it uses uint32 type). (i may be a bit wrong here, but it worked in my case)
2.4. launch vlc from cmd with command -vvv sets the verbose=2 automaticaly
2.5. Repeat steps for launching bluray disk
2.6. open text file with debug log.
Here i used notepad++ program for opening file with logs, because it explicitly shows if file was changed and if i want to reload it.
Text file should be automatically created in the path from BD_DEBUG_FILE variable.
For some reason file size can be displayed as 0KB while vlc is running, but there still will be logs inside. Don't let zero file size discourage you from opening log file!

Great now you got logs from libbluray and can get some insights into what is going on.

!!!From this point on all logs that you see are from file specified in BD_DEBUG_FILE variable. (don't confuse it with stuff you can see in Messages window in vlc ui)
*some of the following logs are split between several messages, please treat them as single continious log. (there is hard limit on number of characters in a single message, so it has to be done)

Part 2.1
Here is an example of libbluray log when everything is working as expected (i mean no issues, menues works)
i open bluray disk with menus, let it play till it gets to menu and stop playback by pressing square in the menu:

Part 2.2
log continues

Part 2.3
log continues 2

Part 2.4
log finished

Rollback Java to an earlier version: https://forum.videolan.org/viewtopic.ph ... 66#p527066 (post written by Don_Bubbles)

Part 3.1
What to look for in the log:
1. Paths
First of all look for JAVA_HOME (JavaHome) paths. There you will see if vlc is loking for java in the expected directories.

2. Is java succesfully loaded
Here is log when i try to load uncompatible jre version with vlc 3.0.17 *this log is a bit truncated

I haven't tried but i suspect that you will see similar messages when trying to use jre-8u341 which is known to have compatibility issues https://forum.videolan.org/viewtopic.ph ... nu#p528023
Here i've got the file "C:\Program Files\Java\jre1.8.0_321\bin\server\jvm" but libbluray can't load it. As far as i know (after some googling) "The specified module could not be found" message is misleanding, and hides from you that the file is here, but doesn't contain required methods.
If you see this kind of errors on whatever vlc version you are on, i suppose the best way is to try other jre versions or move to older vlc version (in my example i moved from vlc 3.0.17 to 3.0.16)

Part 3.2
3. Is there some missing dependencies
Sometimes vlc can load bluray with menu, but get stuck right after start of playback, but before showing the menu.
I've got that case when i was using vlc 3.0.16 and jre-8u321-win64.
I've got 2 machines with same vlc\jre versions, and on one everithing was working, but on the other one with freshly installed windows playback keep hanging just before menu would show.
Here is libbluray log from that hanging machine:
*log part 1

Part 3.2
log part 2
Notice that jvm was successfully found and loaded, but we've got some exceptions while loading java awt classes (like java.awt.Toolkit, java.awt.BDGraphicsBase, java.awt.BDFontMetrics)
Awt.dll is a part of java, and it means that we've got some system dll missing, that are required for normal java operation.
In the next part i will give step by step guide how to fix your dependencies.

Part 3.3
Fixing missing dependencies.

I was a bit dumbfounded when i faced issue regarding absence of system dll's, but luckily i've got another machine with the same vlc\jre versions where everything worked.
So here is how i've got around it.
There is a tool called dependency walker https://www.dependencywalker.com/ which analyses dll's and shows their dependencies and which of them are missing on your machine.
So i've run it twice on both machines, got the list of all missing dependencies (for each machine) and compared them. The difference between the lists were the required dll's that were missing from hanging machine.
!!! List of missing dll's to compare to is provided below
After installing missing dll's on second machine everything worked.
I'm definetely was missing C:\Windows\System32\CONCRT140.DLL and maybe C:\Windows\System32\msvcp120.dll (i'm not sure about last one because i've downloaded it before i've got the lists). These dll's can be obtained from installing Microsoft Visual C++ Redistributable 2015\2013 respectably (or just google how to get them, prefer answers from (answers.)microsoft.com, because there you will found links for download directly from microsoft website)

So here i'm gonna talk about following software with specific versions:
jre-321u-win64
dependency_walker 2.2.6000
but this guide can be applied to any dll

1. Download dependency walker
https://www.dependencywalker.com/
2. Locate dll which depencies you want to analyse
Here we are looking at C:\Program Files\Java\jre1.8.0_321\bin\awt.dll
I've decided to look at this dll because of errors in part 3.2
I saw that the errors where in classes staring with java.awt (java\awt) so i just used file exlorer search to look for any file containing "awt" in C:\Program Files\Java\jre1.8.0_321 folder.
The only one found was awt.dll
3. Open dependency walker program and select required dll.
Press File->Open
It may take some time (it may look like dependency walker is hanging but it's doing it's thing) to analyze file.
For time estimates, it took about several minutes (let's say ~3-5min) to analyze awt.dll on my pcs (not powerful, i7-2600k and i7-6600U).
Awt.dll size is about 1.46mb, analyzing 12kb random dll takes several seconds.
4. Select missing dlls
Wait till analysis is complete, it will finish with error message telling you that sone dependecies are missing.
In te middle of the Dep_walker window (below the dependecy tree shown at the top) you will see a vertical list of modules.
In the frist column you will see different icons, in the second column named "Module" you will see module names.
We are interested in the modules marked with yellow circle with question mark inside.
Order modules by their icons (should be sorted by default)
Select all marked modules by clicking on the first one, then scrolling to the last marked module and shift+click it to get selection from first to last.
After that right click selection and press "Copy file names" in popup menu
5. Compare list of missing dll's with provided list
Below i will provide list of missing dlls from my machine where vlc3.0.16\jre-8u321-win64 installed
By finding difference with that list you may find what dll's you need to download
In my case i found out that i was missing CONCRT140.DLL
You may use any online service for this task, i've personally used compare plugin for notepad++.
6. Install missing dll's by googling how to get them)))

Part 3.3.1
dll's to compare to Part 1

Part 3.3.1
dll's to compare to Part 2

Part 3.3.1
dll's to compare to Part 3

Part 3.3.1
dll's to compare to Part 4

Part 4.
This message concludes this mini guide, thank you for your time.
I hope you find it helpful for solving your problems with bluray menu playback.
Please comment here if you solved other type of issues which can be found out by loking at libbluray logs. (or just post link to threads where you describe how to fix this kind of problems)

Thanks for the awesome detailed steps! I found a really weird issue, not sure whether it's a VLC or libbluray bug or something else. One of my BDMV folder backups created with MakeMKV was automatically named "The Abbott and Costello Collection_ Disc One#1AA2". When I open it with VLC with the menu, it it shows a small thumbnail, the playback progress bar has an orange section bouncing back and forth--and it sits forever. Changing the hash (#) in the folder name to a space ( ) causes it to start working.

I tried to reproduce with a different BDMV folder backup, replacing a space ( ) in the folder name with a hash (#). But menu kept working fine.

I tried VLC 3.0.18 with both jdk-8u321 and jre-8u361, and got same results. Perhaps these logs are helpful? Split into three posts due to length limits.

PART ONE OF THREE

PART TWO OF THREE

PART THREE OF THREE