Erratic behavior when playing MP4 files on 4.25

[agustincordes]

Hi all! We're having a strange issue with this plugin. Our main goal is to use it to play MP4 files on Linux. We were able to make it work with Unreal 4.25 thanks to @HBGames fix (https://github.com/HBGames/VlcMedia) and @Alexei-Kondratiev instructions to compile the libraries on Ubuntu 18.04 (https://github.com/Alexei-Kondratiev/VlcMedia).

However, this problem seems to be affecting Windows 10 as well: the first time a video is played after opening the media source, it will fail. Unreal immediately throws the OnEndReached event and only the first frame of the video is shown. The second time will seemingly work, but the plugin still behaves erratically.

I know most errors logged by the library can be ignored, but there's one that stands out: missing lock callback. This is always logged when the video fails. We did implement this fix: fdsalbj@a33a3db

Any clues about this? It would be simply amazing to ensure Unreal can play MP4 files everywhere thanks to this plugin. Thanks in advance!