VLCMediaPlayer.jumpBackward behaves strangely on Opus files (jumping forward instead)
This is a pretty strange issue: It surfaced in the Nextcloud iOS app and I have been able to reproduce it consistently there, but any attempts at creating a minimal example app don't seem to exhibit the issue. The fact that this only happens on Opus files (and not e.g. on MP3s), has led me to believe that this could be an upstream issue (in VLCKit or VLC) as opposed to e.g. an issue with the app or the UI bindings to the VLCMediaPlayer
instance.
The problem: Calling VLCMediaPlayer.jumpBackward
while playing an Opus file seems to magically jump forward by a few seconds instead. Here's an annotated demo of the problem in the Nextcloud app:
What's particularly strange is that my attempt at creating a minimal reproducible example app seems to work perfectly fine. For reference, here is the code of my failed attempt at reproducing the bug in isolation.
Here is the Nextcloud code I've been debugging (only very slightly modified from the Nextcloud upstream to include some more logging) and here is the issue I have filed in the Nextcloud app, also including a short demo.
Any ideas on what the issue could be or how to debug this further?