plex_loadfile_hook

This commit on mpv broke backwards compatibility with how Plex utilizes the loadfile command to play video. This release fixes it via a hack, and allows using the latest version of libmpv.

Why is this an issue? Plex uses an incredibly old version of libmpv which lacks many new improvements, most notable one being Dolby Vision tonemapping (either to SDR/HDR) via the gpu-next video output driver. Other good reasons include improved support for graphic APIs, ASS performance improvements and the better high-quality preset being included.

How this works

A detour is placed on mpv-2.dll.mpv_command_node to catch the playback URL. It is parsed and then passed to mpv with the correct arguments. This mod also fixes playback for *.plex.direct URLs when using upstream mpv. This release makes use of DLL proxying to inject plex_loadfile_hook when Plex loads Direct3D 11.

Installation

Windows only. Binaries provided for x86_64, but it should work for 32-bit as well.

1. Download d3d11.dll from the latest release and put it in your Plex installation folder. (e.g. C:\Program Files\Plex\Plex)
2. Grab the latest libmpv (mpv-dev) build from shinchiro's provided builds, rename libmpv-2.dll to mpv-2.dll, and replace mpv-2.dll in the Plex installation folder with it.

Use new settings

Open %LOCALAPPDATA%\Plex and start adding settings to mpv.conf.

I recommend the following as a basis:

# The new video output driver; allowing better color management and support for DV/HDR tonemapping.
vo=gpu-next

# A preset for higher quality playback. Comment out or replace with `profile=fast` if playback performance is unacceptable.
profile=high-quality

# Refer to the manual; too long to elaborate. Replace with your own choice if needed, but this is a good generic option.
hwdec=auto-safe

# Allows for HDR passthrough & automatically setting the display to HDR mode, when using the Vulkan API.
# Could be set to `no` if on an SDR display.
# On mpv version 0.40, there's a default `auto` value which will display HDR content directly if the display supports it. Or it will use mpv's tonemapping for it otherwise.
# target-colorspace-hint=yes

# Replace with gpu-api=d3d11 if you're having issues.
# vulkan will allow automatic switching to HDR when playing DV content, and will display DV tonemapped to HDR.
gpu-api=vulkan

# Replace with your display's bit depth. Will be 8 for most SDR displays, and 10/12 for most HDR/DV supporting ones.
dither-depth=10

Refer to the mpv manual (linked in resources) for additional settings.

Resources

• mpv manual
• perfect-dll-proxy
• MinHook