mpv-synth is a modern Windows media player with frame interpolation, automatic HDR colour management, a filmstrip timeline, and one-click browser streaming.
The third-party ecosystem hasn't kept pace with how people actually consume media. The most popular options are functional, but they feel like they were designed a decade ago — in most cases, they were.
Clunky interfaces assembled from stock Windows form components. Windows that linger on your desktop doing nothing after playback ends. No memory of where you were in a file.
No awareness that you might want to move on to the next episode automatically. No consideration of the display you're watching on, the colour space of the content, or whether the motion could benefit from interpolation.
You open a file — it plays. When it's done, it's done. It just gets out of the way. There's no application to wrangle. It feels like a natural feature that should be part of any modern operating system.
That's the experience mpv-synth is built to deliver on Windows. Open a video file and it plays, full stop. No splash screens, no library to build, no window hanging around after playback ends. When there are no more videos to watch in a folder, the player closes itself. It knows its job is done.
Download the zip and extract it where you want the installation to live. C:\Program Files\ is the recommended location.
This single script downloads the latest versions of mpv, ffmpeg, ffprobe, yt-dlp, and VapourSynth*; registers file associations; creates Start Menu and AutoPlay entries; then removes itself.
The install is interactive — read the prompts as they appear. Defaults are set to the recommended choices throughout, with one exception: if your machine is more than roughly a decade old, choose x86_64 at the first prompt rather than the default x86_64-v3. Any modern hardware should handle v3 fine.
mpv-synth registers itself as the default handler for common video formats. If Windows asks which app to use, select mpv-synth and tick "Always". That's it — everything else is handled automatically from this point forward.
mpv-synth is built on mpv — one of the most capable media engines in existence — and wraps it in the experience layer that was always missing. Optional browser extensions for Chrome-family browsers and Firefox add a "Play in mpv-synth" right-click option to any link or page with embedded video, routing the stream directly through the player.
Full VapourSynth pipeline powering buttery-smooth playback at 30, 60, 90, 120, or 144fps. Switch presets from the right-click menu or a keypress. Entirely optional — the player is equally happy without it.
ICC-detect reads the colour space and HDR metadata of every file on load. HDR content is passed through natively on capable displays and tone-mapped correctly on SDR — automatically, every time.
150 evenly-spaced thumbnail slices composited into the seekbar, giving you an at-a-glance map of the entire file. Hover for a frame-accurate preview. Jump to any scene with a click.
When a video ends, mpv-synth moves to the next file in the folder automatically. When you quit mid-file, it resumes exactly where you stopped — no manual bookmarking required.
The auto-subs plugin activates a subtitle track only when it matches every term in a configurable list — so match=en,forced picks up English (Forced) automatically, while leaving everything else untouched. Fine-grained, or one-word simple.
Press U from within the player to pull the latest versions of mpv, ffmpeg, yt-dlp, plugins, and the updater itself. The entire toolchain stays current with a single keypress — or run updater.bat directly without opening the player.
The installer handles all dependencies — mpv, ffmpeg, VapourSynth, and the interpolation libraries — automatically.
Download the zip and extract it where you want the installation to live. C:\Program Files\ is the recommended location.
This single script downloads the latest versions of mpv, ffmpeg, ffprobe, yt-dlp, and VapourSynth*; registers file associations; creates Start Menu and AutoPlay entries; then removes itself.
The install is interactive — read the prompts as they appear. Defaults are set to the recommended choices throughout, with one exception: if your machine is more than roughly a decade old, choose x86_64 at the first prompt rather than the default x86_64-v3. Any modern hardware should handle v3 fine.
Open portable_config\mpv.conf and set your preferred language codes:
# preferred audio language
alang=ja,jpn,en
# preferred subtitle language
slang=en,engFor subtitles to activate automatically, edit portable_config\script-opts\auto-subs.conf and set your match terms. A track is only selected if it matches every term in the list — so you can be as broad or as specific as you like:
# English forced subs only (the default)
match=en,forced
# Any French subtitle track
match=fr
# Nothing auto-selects — mpv picks based on slang above
enabled=nomatch list is comma-separated with no spaces. Each entry must appear somewhere in the subtitle track's name or language tag for it to be selected. The default match=en,forced targets tracks labelled something like English (Forced).
mpv-synth registers itself as the default handler for common video formats. If Windows asks which app to use, select mpv-synth and tick "Always". That's it — everything else is handled automatically from this point forward.
portable_config\mpv.conf and look at the PERFORMANCE PROFILE section. Setting vo=gpu and gpu-context=d3d11 will make the biggest immediate difference. Any machine capable of running Windows 11 should handle mpv-synth smoothly.The browser extensions are completely optional — mpv-synth works perfectly as a local player without them. They add a "Play in mpv-synth" right-click option to any page with embedded video in Chrome-family browsers and Firefox.
Extract installer\mpv-synth-extension.zip in place. Then, inside the native\ folder, right-click install.bat and choose "Run as Administrator". This registers the Python host that allows the browser to securely launch mpv. You only need to do this once.
Chrome / Edge / Brave / Vivaldi: Go to chrome://extensions, enable Developer Mode, click "Load unpacked", and select the chrome\ folder.
Firefox: Go to about:debugging#/runtime/this-firefox, click "Load Temporary Add-on…", navigate to the firefox\ folder, and select manifest.json. For a permanent install, see the README inside the extension zip.
Click the mpv-synth icon in your toolbar. Fill in the mpv Location (the folder containing mpv.exe) and Config Location. If you installed to the default location, you can leave the pre-filled placeholders as-is. Click Save.
In the same config page for the extension you can adjust the slider to adjust the amount of video you'd like to have cached, the default 30 seconds is a good balanced amount. Lowering it may start playback faster, depending on your internet speed, and raising it provides more protection against running out of buffered video.
All actions are available in the right-click menu with keyboard shortcuts displayed alongside them. Here are the ones you'll reach for most often.
| Key | Action |
|---|---|
| Escape | Toggle fullscreen |
| Space | Play / Pause |
| q | Quit — position saved automatically |
| ← → | Seek 5 seconds; hold Ctrl for 5 minutes |
| ↑ ↓ | Seek 30 seconds forward / back |
| a / d | Previous / next chapter |
| w / s | Step one frame forward / back |
| , / . | Previous / next file in folder |
| [ / ] | Playback speed −10% / +10% |
| { / } | Playback speed ½× / 2× |
| Backspace | Reset playback speed |
| - / = | Volume down / up |
| v | Toggle subtitle visibility |
| Ctrl+v | Cycle subtitle tracks |
| I | Edit keyboard bindings & menu |
| M | Edit player configuration |
| U | Update all components (mpv, ffmpeg, yt-dlp…) |
All shortcuts and right-click menu entries are defined in portable_config\input.conf.
Each line follows this pattern:
[key] [action] #menu: Top Level > Submenu > Item nameFor example:
Right seek 60 #menu: Navigate > Skip > 1 min forward#menu: portion is optional — omit it for a binding with no menu entry. Use _ as the key for a menu entry with no keyboard shortcut. Each > adds a submenu level. Open the file via Tools → Edit Config in the right-click menu, or press I.
All plugin options live in portable_config\script-opts\ — one .conf file per plugin, named accordingly. The main player options are in portable_config\mpv.conf.
The filmstrip defaults to 150 thumbnails generated across 4 concurrent threads. This gives a dense, visually rich timeline and runs smoothly on modest hardware — tested on a 65W Ryzen 7 mini-PC.
# portable_config\script-opts\filmstrip.conf
thumbnail_count=150
max_concurrent=4max_concurrent to 2 or 1 — thumbnails will build more slowly, but playback won't be affected. thumbnail_count=100 still looks great. Set thumbnail_count=0 or enabled=no to disable the filmstrip entirely.
Several bundled components are used in modified form — patched for reliability, this setup's specific quirks, or to resolve issues found during testing.
The player at the core of everything. Extraordinarily capable, extraordinarily extensible.
The starting point and inspiration for this project.
The frame processing framework powering interpolation.
The interface layer. The de facto standard for mpv UI.
Native Windows right-click menu integration. Modified for this setup.
Timeline hover thumbnails. Modified — stall watchdog added for reliability.
Native Windows file/folder open dialog integration.
Recently played files list.
Libraries for VapourSynth integration and interpolation.
This started as a simple integration project and turned into months of debugging Lua timing races, writing plugins from scratch, and learning the internals of a rendering pipeline I didn't know existed. The software is free. If you've gotten anything out of it, I'd genuinely appreciate the gesture.