Black screen during movie playback (audio still plays) on some AMD cards [Unity bug]

A user reported the following:

>
> > Is it normal for the Hirukowashi console intro is only music, but no visuals are shown?
> > For me just a black screen with the music appeared
> > I experimented a bit with it, but no matter what I choose with Hirukowashi the opening FMV is not shown. It only plays the music, but I have a black screen the whole time.
>
> Did the movies work before (for other console arcs or other chapters)?
>
> > They always worked fine for the other Arcs and I tested yesterday it worked for Watanagashi. It is only on Rei now, that I have this. I also looked in the game folder, but there they worked fine. And I have a Windows 10 notebook.
>
> When did you install the Rei mod?
>
>> Two months ago, but I updated it to the newest version on Friday

For Rei, the video playback uses a different way of playback (it uses Unity's built in player), so I guess having some issue isn't totally unexpected.

I asked them to send their logs, and the error message:

```
Got null handle from IDXGIResource::GetSharedHandle.
(Filename: Line: 1830)
```

appears after movie playback starts.

Googling this turns up a bug in unity: https://forum.unity.com/threads/video-player-crashing-with-got-null-handle-from-idxgiresource-getsharedhandle.867523/

On the Unity issuetracker, it says it is a problem with specific AMD GPUs: https://issuetracker.unity3d.com/issues/video-player-fails-to-start-playing-and-null-handle-errors-are-thrown-when-running-unity-editor-slash-build-with-specific-hardware

> Earlier generations of Radeon switchable graphics (R7 340, R7 440, 520, 530) have driver issues that make then incompatible with Unity's hardware-accelerated video decoding.

I'm guessing the version of unity we use does not have the fixes described on the issuetracker.

----

## Possible Fixes

- Do nothing: we have only had one report of this problem ever, although it would affect people with same hardware configurations
- Just add info about this bug to the wiki and/or changelog as a known issue
- Switch to .VP8 video files for all platforms, although that would reduce video quality (the .mp4 files are the originals)
- Disable using the vulkan renderer seems to also be a fix for this problem I read somewhere, but that is usually set through Unity Editor dialogs, not via code, so this may be difficult

For now, I'll probably do nothing, due to how many people this seems to affect. The lack of video playback isn't showstopping either.

----

## Log Files

[Player(2).log](https://github.com/07th-mod/higurashi-rei/files/9846204/Player.2.log)
[Player-prev.log](https://github.com/07th-mod/higurashi-rei/files/9846203/Player-prev.log)
[mod_log_2.txt](https://github.com/07th-mod/higurashi-rei/files/9846201/mod_log_2.txt)
[mod_log_1.txt](https://github.com/07th-mod/higurashi-rei/files/9846202/mod_log_1.txt)

The issue is a Unity video playback bug on specific AMD GPUs, indicated by the 'Got null handle from IDXGIResource::GetSharedHandle' error. Research Unity's video player component and hardware-accelerated decoding. Check the Unity version used in the project and see if an upgrade includes the fix. Examine video file formats (.mp4 vs .VP8) and rendering backends (Vulkan). The logs attached may show the exact error context. A fix likely requires deep Unity engine knowledge or a workaround like changing video encoding or renderer settings.

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