Help with writing Avisynth Plugins

[blaze077]

I am just starting to get into writing Avisynth plugins but got stuck right at the beginning in this guide.

Under the "Compiling Your First Plugin" section, it says:

Copy (C:\Program Files\ or other installation directory then AviSynth 2.5\Extras\avisynth.lib to demosaic\lib

However, there doesn't seem to be any such file anywhere in my Avisynth+ installation folder.

I am using Avisynth+ r2173.

[qyot27]

If you didn't choose to install the SDK when you installed AviSynth+, then those files won't be there.

And because it's gnawing at my brain like a parasite, the section of that guide that talks about licensing is false. The 2.6 (and Plus) C API does not and never has required plugins written with them be released under the GPL. You can use whatever license you like for the plugin, the exception is there in avisynth_c.h and was not removed at any point between 2.5 and 2.6 (unlike the C++ header, but even it had the exception restored when 2.6 Final was released).

[blaze077]

Will keep the licensing thing in mind.

As for the SDK, I just redid the installation with the FilterSDK option enabled and I still do not have an avisynth.lib file anywhere in the installation folder. I have the avisynth_c.h like before.

[qyot27]

Looks like Groucho2004 didn't include the dev files in the install package for that build.

To be fair, if you're looking at building the plugins, you might want to start by building AviSynth+ itself to get a feel for it*. And if you do that, the .lib files will get built.

A guide is in the AviSynth+ source:
https://github.com/AviSynth/AviSynth...ng_avsplus.rst

The only thing that requires mentioning is that after cloning it, you'll want to checkout the MT branch to get the correct updates. Or you can do the checkout at the same time as the clone:

git clone -b MT git://github.com/AviSynth/AviSynthPlus.git

[blaze077]

Thank you. I will try that out tomorrow.

[Groucho2004]

Originally Posted by qyot27

Looks like Groucho2004 didn't include the dev files in the install package for that build.

What dev files? The AVS+ installer script only includes help files if "Filter SDK" is selected.

Edit: The "official" 2.6 Avisynth installer does offer the option to install the C-header and avisynth.lib.

[qyot27]

Actually yeah, now that I think of it, I don't think I'd ever tried installing the AviSynth+ SDK files from the InnoSetup-based installer. I must have been confusing it with the old installer.

Part of why it's not in the new installer is probably the stance that 'AviSynth+ should be supported in your program by using dynamic loading', and that doesn't need the *.lib files. For plugins that gets kind of hairy, though - not saying it can't be done, just that it's somewhat arcane (the FFMS2 C-plugin does it, but I haven't gotten it updated to use AviSynth+'s headers yet).

[blaze077]

I somehow managed to reach the Building Avisynth section of the guide through trial and error and whatever little knowledge I had. However, when I used the following command:

git clone git://github.com/AviSynth/AviSynthPlus.git && cd AviSynthPlus

it gave this message:

-bash: git: command not found

[qyot27]

With msys2 open:

pacman -S msys/git

[blaze077]

Thank you. That worked. Now I get the same error with cmake even though I have installed cmake and it has automatically been added to the Windows PATH directory:

-bash: cmake: command not found

[qyot27]

I'm pretty sure the CMake installer's 'add to PATH' option puts the parent directory in the PATH, not the one we need. It needs to be C:\Program Files\CMake\bin (or C:\Program Files (x86)\CMake\bin if you're on 64-bit Windows) that's added to the PATH.

To check, run

echo %PATH%

from the regular Windows Command Prompt, or

echo $PATH

from inside msys2. Try to find either C:\Program Files\CMake\bin (Command Prompt) or /c/Program Files/CMake/bin (msys2) in the list of directories that show up. If it's *not* in there, then you'll have to either fix or add that directory to the PATH entry manually.

[blaze077]

The directory "C:\Program Files (x86)\CMake\bin" is there in the Windows PATH. The echo %PATH% command in Windows Command Prompt returns all the directories in PATH whereas the msys echo $PATH gives me this:

/usr/local/bin:/usr/bin:/bin:/opt/bin:/c/Windows/System32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0/:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl

[qyot27]

Okay, I see what happened: https://github.com/msys2/msys2.github.io/issues/20

You need to make sure that msys2_shell.cmd has MSYS_TYPE_PATH set to 'inherit' (open it in Wordpad to check so that the Unix-style line feeds are interpreted correctly). But if I'm reading some of those cases right, when opening msys from the Visual Studio Command Prompt, it should be able to recognize that and inherit the %PATH% without the need to edit things.

[blaze077]

Sorry for the late reply. The MSYS_TYPE_PATH was set to 'inherit' already so in the end, I just added the cmake directory manually through the export PATH command. Now I'm stuck on the last part:

cp Output/AviSynth.dll Output/system/DevIL.dll Output/plugins/DirectShowSource.dll \
Output/plugins/ImageSeq.dll Output/plugins/Shibatch.dll Output/plugins/TimeStretch.dll \
Output/plugins/VDubFilter.dll ../$AVSDIRNAME/64bit

This gives me the error:

cp: target '..//64bit/dev' is not a directory

[qyot27]

You didn't set the AVSDIRNAME variable, or closed/reopened the terminal after you'd set it, or tried setting it when you were in the wrong directory. After cloning the git repo, cd into AviSynthPlus, set the AVSDIRNAME variable, back out of the AviSynthPlus directory, create the build and packaging directories, cd into the build directory, and then run the cmake configure and build commands. And after all that's finished, without closing the terminal at any point, then run the cp instructions to copy the .dlls into the packaging directory.

If the stuff actually built, you can find them in the Output/ directory and manually copy them around as you see fit.

[FranceBB]

Slightly off topic but still about "writing an avisynth plugin". I can generally use the avisynth scripting language in an .avs file or use C/C++, link the avisynth header and make a .dll. My question is: is there a way to handle certain tasks in C++, link the avisynth header AND use the avisynth scripting language for some other task INSIDE a C++ project?

[StainlessS]

Francebb, no chance.

Edit: you can use invoke() to call built in filters though, with args that would be familiar.
You can also call external plugs but have to handle errors if not installed.

Mobile

http://avisynth.nl/index.php/Filter_SDK/Env_Invoke


EDIT: Now seeing comments below, changing my reply from "No chance" to "Yes, Every Chance".

[TheFluff]

I'm pretty sure it's possible. You'll have to generate a script and write it to disk since you can't interact with the script interpreter directly, but once you've done that you can be your own host application and feed input/read output as you wish.

The question is why you want to do this, though. Any logic done in Avisynth script is usually easier done in almost any other language, and if you just want to build filter chains all you need to do is interact with the script environment directly by calling env->invoke() as StainlessS points out. The Avisynth video provider in Aegisub is one example of how to create a "script" (read: filter chain) from a C++ application and use it to read video frames.

[Gavino]

Originally Posted by TheFluff

You'll have to generate a script and write it to disk since you can't interact with the script interpreter directly

Yes you can, simply by using env->Invoke() to call the Eval() function on some script language text.

[TheFluff]

Oh right, well there you go then.