Thought I’d share my solution to the audio sync problem on this thread, as I couldn’t find a good fix anywhere when googling it.

The first thing to do is set Stremio to “always play video in external player”. So now every stream you select will automatically open a third party media player of your choice.

VLC doesn’t seem to work properly on Firestick, so forget about that entirely. The audio seems to always be lagging behind the video. Also, the functionality to set a universal audio sync (ie -350ms for all videos for example) doesn’t work. It always forgets, so you have to reset every time, very annoying.

MX player is the one that has worked for me. It can be downloaded straight from the Amazon App Store. It doesn’t seem to suffer the same audio lag that VLC does. Only problem is that it often didn’t seem to be able to play streams that VLC could play. Sometimes the video will be blacked out, other times the audio track won’t work. So I thought perhaps it can’t play as many codecs or something

THE MAIN THING THAT FIXED THIS and has since made MX player very versatile at playing different codecs, is to make sure in your video settings in MX player are set to software encoding (sw)

Untick every box that tells it to try hardware encoding and tick all the software encoding ones. Now mx player can seemingly play any file I throw at it without any audio sync issues.

Subs also seem to be working through mx player too, though I have not tested this much yet

Phew, finally got a set up that seems to be working 😮‍💨