Looks like the issue has returned with the latest Plex-1.45.0.3013 update. Above mentions copying everything into the Plex/Plex directory, I have tried this and it does not work. It was previously working fine on Plex-1.43.4.2971 all that changed was Plex updated. I have replaced the mpv-1.dll since the update and it fails with error code 4294967283. It seems that there is an issue with resolving the stream host. I have provided what I've found below to show that it works fine with Plex's dll but not SVP's dll. All that is changed is the mpv-1.dll:
Plex's original mpv-1.dll:
Jun 08, 2022 00:52:58.714 [7036] DEBUG - [MPVEngine/mpv] cplayer: Setting option 'stream-lavf-o' = 'resolve_hosts=[XXXXXXXXXXX.plex.direct:XXXXXXXXXXX]' (flags = 16)
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] cplayer: Running hook: ytdl_hook/on_load
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] ytdl_hook: ytdl:// hook
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] cplayer: Set property: start="+1796" -> 1
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] ytdl_hook: not a ytdl:// url
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] cplayer: Set property: aid="no" -> 1
Jun 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] cplayer: Set property: sid="no" -> 1
un 08, 2022 00:52:58.715 [7036] DEBUG - [MPVEngine/mpv] ffmpeg: Opening https://XXXXXXXXXX.plex.direct:32400/library/parts/2151/1499763098/file.mkv?X-Plex-Session-Identifier=n6o2qylyc6vqah1jf6j4v9xd&X-Plex-Product=Plex%20for%20Windows&X-Plex-Version=1.45.0.3013-1676042f&X-Plex-Client-Identifier=oti94rrvujjg47wu7cq8df9q&X-Plex-Platform=windows&X-Plex-Platform-Version=10.0.22000&X-Plex-Features=external-media%2Cindirect-media&X-Plex-Model=standalone&X-Plex-Device-Name=SurfaceBook2&X-Plex-Device-Screen-Resolution=1481x858%2C1714x1143&X-Plex-Client-Profile-Name=Plex%20Desktop&X-Plex-Token=xxxxxxxxxxxxxxxxxxxx&X-Plex-Language=en&Accept-Language=en
Jun 08, 2022 00:52:58.768 [7036] DEBUG - [MPVEngine/mpv] ffmpeg: Mime-type: 'video/x-matroska'
Jun 08, 2022 00:52:58.768 [7036] DEBUG - [MPVEngine/mpv] demux: Trying demuxers for level=normal.
Jun 08, 2022 00:52:58.768 [7036] DEBUG - [MPVEngine/mpv] mkv: Seeking to 3117326564 to read header element 0x1c53bb6b.
Jun 08, 2022 00:52:58.768 [7036] DEBUG - [MPVEngine/mpv] ffmpeg: stream level seek from 16384 to 3117326564
Jun 08, 2022 00:52:58.814 [7036] INFO - [MPVEngine] Resuming playback.
Jun 08, 2022 00:52:58.814 [7036] DEBUG - [MPVEngine/mpv] cplayer: Set property: pause=no -> 1
Jun 08, 2022 00:52:58.815 [7036] INFO - [MPVEngine] Playback has resumed.
Jun 08, 2022 00:52:58.815 [10876] DEBUG - [QHotkeyInput] Playback state is now 'Playing'
SVP's mpv-1.dll:
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] cplayer: Setting option 'stream-lavf-o' = 'resolve_hosts=[XXXXXXXXXXX.plex.direct:XXXXXXXXXXX]' (flags = 16)
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] cplayer: Running hook: ytdl_hook/on_load
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] ytdl_hook: ytdl:// hook
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] cplayer: Set property: start="+650" -> 1
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] ytdl_hook: not a ytdl:// url
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] cplayer: Set property: aid="no" -> 1
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] cplayer: Set property: sid="no" -> 1
Jun 08, 2022 00:49:40.008 [10812] DEBUG - [MPVEngine/mpv] ffmpeg: Opening https://XXXXXXXXXX.plex.direct:32400/video/:/transcode/universal/start?hasMDE=1&path=%2Flibrary%2Fmetadata%2F6110&mediaIndex=0&partIndex=0&protocol=http&fastSeek=1&directPlay=0&directStream=1&subtitleSize=100&audioBoost=100&location=lan&addDebugOverlay=0&autoAdjustQuality=0&directStreamAudio=1&advancedSubtitles=text&session=w88l4lzkqkk4r1neskd6gfga&offset=650&subtitles=auto©ts=1&Accept-Language=en&X-Plex-Session-Identifier=tkt3rheiwgook11zjim7r5os&X-Plex-Chunked=1&X-Plex-Incomplete-Segments=1&X-Plex-Product=Plex%20for%20Windows&X-Plex-Version=1.45.0.3013-1676042f&X-Plex-Client-Identifier=oti94rrvujjg47wu7cq8df9q&X-Plex-Platform=windows&X-Plex-Platform-Version=10.0.22000&X-Plex-Features=external-media%2Cindirect-media&X-Plex-Model=standalone&X-Plex-Device-Name=SurfaceBook2&X-Plex-Device-Screen-Resolution=1481x858%2C1714x1143&X-Plex-Client-Profile-Name=Plex%20Desktop&X-Plex-Token=xxxxxxxxxxxxxxxxxxxx&X-Plex-Language=en
Jun 08, 2022 00:49:40.011 [10812] ERROR - [MPVEngine/mpv] ffmpeg: tcp: Failed to resolve hostname XXXXXXXXXXX: The name does not resolve for the supplied parameters
Jun 08, 2022 00:49:40.011 [10812] ERROR - [MPVEngine/mpv] stream: Failed to open https:/XXXXXXXXXXX -----------(I shortened this)
Jun 08, 2022 00:49:40.011 [10812] DEBUG - [MPVEngine/mpv] cplayer: Opening failed or was aborted: https://XXXXXXXXXXX
Specifically looking at the "ffmpeg: Opening" line, you can see there is a different structure to how the URL is passed through. This seems to be the root causes of resolve error and may need the SVP dev team to recompile the MPV dll for the new Plex URL structure.
Any assistance from the dev team would be appreciated as this is one of the main reasons I have SVP