Plugins

With these functions you can add external filters (DLLs) to the AviSynth script environment.

LoadPlugin

Loads one or more standard (C++) AviSynth plugins.

LoadPlugin ("filename" [, ...])

• filename is the path of the .DLL file(s).

LoadCPlugin

Loads so-called AviSynth C-plugins. C-plugins are created in pure C (unlike ordinary Avisynth plugins which are created with MS C++), use a special C API, and must be loaded with LoadCPlugin.

LoadCPlugin ("filename" [, ...])
Load_Stdcall_Plugin ("filename" [, ...])

• filename is the path of the .DLL file(s).
• The plugin's documentation should advise you if LoadCPlugin is needed.
  
• Load_Stdcall_Plugin is merely an alias or alternate name.

LoadVirtualDubPlugin

Loads a plugin written for VirtualDub. These are distributed as special DLLs with the file extension .VDF.

LoadVirtualDubPlugin ("filename", "filtername", preroll)

• filename is the path of the .VDF file.
• filtername is the name given to the plugin function after loading in AviSynth.
• Some filters' output depends on previous frames; for these, preroll should be set to a suitable number.
• VirtualDub filters support only RGB32.
• Usage example (ColorTools) – see here (doom9).
• See FAQ using Virtualdub plugins for more information.

LoadVFAPIPlugin

Loads VFAPI plugins (eg, TMPGEnc import plugins).

LoadVFAPIPlugin ("filename", "filtername")

• filename is the path of the .DLL file.
• filtername is the name given to the plugin function after loading in AviSynth.
• The plugin's documentation should advise you if LoadVFAPIPlugin is needed.

It is possible to put all plugins and script files with user-defined functions or (global) variables in an autoload directory, from which all files with the extension .AVSI and .DLL are loaded at startup, then unloaded and reloaded dynamically as the script needs them.

.AVSI scripts in this directory should only contain function definitions and global variables; they should not have a main processing section (else strange errors may occur). It also is not recommended to put other files in that directory.

The directory is stored in the registry. You can use double-clicking a .REG-file with the following lines to set the path (of course inserting your actual path):

REGEDIT4

[HKEY_LOCAL_MACHINE\SOFTWARE\Avisynth]
"plugindir2_5"="c:\\program files\\avisynth 2.5\\plugins"

The order in which function names take precedence is as follows:

1. User-defined function (always have the highest priority)
2. Plugin (external) function (higher priority than built-in)
3. Built-in (internal) function

Inside those groups the function loaded last takes precedence; there is no error in a namespace conflict.
It follows that there is no harm in loading the same plugin more than once.^{[dubious – discuss]}

A problem that may arise when multiple plugins have functions with the same name. You won't know which function will be called in your script, as this will depend on loading order. To call a particular function in this situation, AviSynth's DLLName_function() feature automatically creates prefix aliases; so for example, foo.dll's bar() function may be called as foo_bar(). This works both for auto-loaded plugins and for plugins loaded with LoadPlugin.

Suppose you have the plugins mpeg2dec.dll and mpeg2dec3.dll in your autoload directory;
if you want to load a .d2v file with mpeg2dec.dll (which outputs YUY2):

# using mpeg2source from mpeg2dec.dll
mpeg2dec_mpeg2source("F:\From_hell\from_hell.d2v")

or with mpeg2dec3.dll (which outputs YV12):

# using mpeg2source from mpeg2dec3.dll
mpeg2dec3_mpeg2source("F:\From_hell\from_hell.d2v")