DirectShow subtitle provider based on libass
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Latest commit 8acdfaa Nov 19, 2017



AssFilterMod is a fork of AssFilter by Alex Marsev.

Open-source DirectShow subtitle renderer based on libass and the SubRenderIntf interfaces. Like the well known XySubFilter, AssFilter don't render the subtitles directly onto the video. It instead communicate directly with the video renderer to send the subtitles. This process allow the video renderer to do what it wants with the subtitles.

AssFilterMod is a version of AssFilter with new features and bug fixes:

  • Added the Settings and Status tabs
  • Added support for SRT subtitles
  • Works with built-in video renderers in MPC-HC
  • Fix crash when the subtitle track is changed
  • Use latest versions of libraries
  • Auto-loading of external subtitles

General Settings:


Multiple folders need to be seperated by using the delimiter ; in the External Subtitles Folders. Note: Only subfolders of the currently playing media file folder can be used.

SRT Settings:


In the Custom Tags edit control, you can enter Ass Tags and customize your SRT subtitles the way you want.

Ex: If you want your subtitles to be BOLD, enter {\b1}.

Important notes:

  • All tags that you use in the Customs Tags will overwrite the default settings.
  • Settings are saved in the registry: HKEY_CURRENT_USER\Software\AssFilter
  • Only ASS and SRT subtitles are supported.


Windows Vista, 7, 8, 8.1 and 10 (32 and 64 bits)


Can be found here


Compiling AssFilterMod is pretty straightforward:

  • Have Visual Studio 2015 Update 3 or Visual Studio 2017 installed.
  • Check out master branch of assfiltermod.
  • Ensure that all submodules are up-to-date by running git submodule update --init --recursive from inside the tree.
  • Open assfiltermod.sln solution file and build.

3rd-party libraries


  • alexmarsev For the great AssFilter working prototype
  • LAV Filters Nevcairiel's awesome DirectShow Media Splitter and Decoders
  • MPC-HC Light-weight media player for Windows
  • stackoverflow Not a project, but a lot of useful ideas and code
  • VideoLAN Org VLC Media player (SRT subtitles parser code)