Introduction

Notes: • This guide and the file downloads are for Windows 32bit and 64bit systems running later than Windows XP. Be aware though that AVISynth functionality on 32bit is limited due to the lack of some filters/plugins and also reduced available system memory. • Following this will guide install AVISynth+. All references in this guide to “AVISynth” mean “AVISynth+”. There are other versions of AVISynth. It will also guide you to installing a collection of common AVISynth plugins/filters, including all the files for QTGMC, the high-quality deinterlacer. • Due to the need to manually add files to some folders in the Program files (x86) folder and Windows folders, you will need to be logged on to Windows as an Administrator. • Some of this process may require access to the full Windows right-click menu. There is a link at the bottom of the modern RC menu that will take you to the old-style complete menu. • I take this opportunity to thank @Cholla from VideoHelp for their assistance in preparing this page.

Caution

This guide requires pasting four files into Windows system folders. Please exercise care to prevent deletions of Windows files. You follow this procedure at your own risk.

Why this guide?

I’ve written this guide and created the downloads because I found that the majority of the difficulty in AVISynth and QTGMC is actually setting it all up. Arcane resources, located in cryptic folders such as CLANG and MSVC, make life a misery. But when it’s all set up, provided you’re happy with a bit of texting to make up your AVISynth (AVS) scripts, it is reasonably straightforward to use and the results can be astounding. The trick comes in knowing what plugins/code to use, but at least when it is set up, you can concentrate on the usage part instead of sweating, grumbling and possibly losing interest over what is, where is and/or how to make, an AVSI or a DLL that is reported to be missing.

What is AVISynth?

AVISynth is a video processing environment which operates by using a script file system (.AVS files), also called a “frame server” because it “serves” the video, after being processed, to the program that has opened the AVS file. At this point, the video hasn’t been rendered or encoded. That will only occur when you do a Save action. The script files are opened in third-party programs such as Virtual Dub which display the filtered video which can then be edited further and/or exported in your desired format. QTGMC is arguably the best deinterlacer around. QTGMC is a taxing process on your computer; on slower machines it may take a long time to encode videos. While this guide will get you going with the very basics of AVISynth and QTGMC, I would urge you to consult the AVISynth and QTGMC wikis to broaden your knowledge of how they work, in particular the various settings for each filter. While I use the basic QTGMC (preset=”fast”) filter here, QTGMC actually has many sub-settings which are put in the brackets. For example, a QTGMC line could be: QTGMC (preset="slow", matchpreset="slow", matchpreset2="slow", sourcematch=3, tr1=2, tr2=1, NoiseTR=2, sharpness=0.1)

AVISynth Components

There are three components to AVISynth: • The program files themselves, which are installed into the Program Files (x86) folder on your system drive using the installation file; • The various plugins/filter files, sometimes called dependencies, which go into the plugins folders in the AVISynth parent folder in the Program Files (x86) folder; • AVISynth scripts, created by you, which are opened in various programs such as Virtual Dub, and which produce the results of the filters you’ve added to the scripts. The installation is very simple. The main hassle with AVISynth is getting all the plugins/dependencies set up. I have made that easy by including all the common dependencies in a ZIP folder.

Bitness 32/64

One confusing aspect of using AVISynth is the plethora of 32 or 64 bit versions and plugins/filters. In a nutshell: • AVISynth+ will run in 32bit or 64bit environments; the same install file works with both. • A 32bit computer will not run 64bit programs meaning, for example, that VDub2 64bit will not run on a 32bit computer. However, 32bit programs will run on a Win64bit computer. • In most cases, there are separate 32bit and 64bit versions of plugins, hence the 2 separate plugins folders. • The program that opens the AVS script determines what bitness is used. For example, if you open an AVS script in Virtual Dub 2 32bit, AVISynth+ will access the 32bit plugins. If you open an AVS in VDub2 64bit, AVISynth+ will access the 64bit plugins. • Which to use? Some plugins are 32bit only, and some are 64bit only. If there is a particular plugin you need to use, you will have to open the file in the appropriate bitness (32bit or 64bit) program. That said, in my experience, every script I have run has opened OK in 64bit. In other words, all the plugins I’ve needed have been available in 64bit. Be aware though that there are plugins/filters that only exist in 32bit form. • A 64bit workflow will mean that much more memory is available. I have had occasions where, with 32bit VDub2, I have had memory halts with QTGMC when combined with other plugins. On 64bit VDub2, I have had no such issues.

Installation

Downloads

Download these files:

AVISynth Plus

https://github.com/AviSynth/AviSynthPlus/releases/ download/v3.7.5/AviSynthPlus_3.7.5_20250420_vc redist.exe

QTGMC files and other Plugin/Filter files

This zip file (53MB) contains all the plugin/filter files you’ll need to set up and run QTGMC and various other common filters. It is your responsibility to keep them updated or to add other plugins as required by your scripts. AVISynth Plugins Package 20241105 Download this zip file to a suitable location; it doesn’t matter where, as long as you can find it later.

Files Set up

AVISynth Program File

Note: If you already have AVISynth+ installed, this installer will simply overwrite the current installation. All your plugins folders will remain intact. Run (DC) the AVISynth+ exe file to install AVISynth+. You will get warnings from Windows about the apparent dodginess of the EXE file. Ignore. Click on More Info, then Install and Install. AVISynth installs on your system drive into the “Program Files(x86)” folder. The AVISynth+ main folder has the two “+” plugins folders. “plugins+” and “plugins64+”. This is what a standard installation looks like on the system drive. There may be “non plus” plugins folders as well, but we won’t be using those.

Plugins Folders

Locate the downloaded Plugins Package ZIP file, RC on it and choose Extract All… and click Extract…. A folder will open, containing the various plugins folders. Note: the plugins included here are only the common ones I have collected. There are hundreds of others that are available, having all sorts of functions/effects. If a script tries to use (“call”) a plugin that isn’t installed, you’ll get an error message describing what is missing, which should be enough to find details on it on the AVISynth Wiki homepage on the web, or just do a search for “AVISynth Santiag”, for example. Assuming Windows is installed on the C: drive:

32bit Windows

1. Copy the two files in folder 1 to your C:\Windows\System32 folder 2. Copy all the files in folder 4 to your C:\Program Files (x86)\AviSynth+\plugins+ folder.

64bit Windows

1. Copy the two files in folder 2 into your C:\Windows\System32 folder. 2. Copy the two files in folder 3 into your C:\Windows\SysWOW64 folder. 3. Copy all the files in folder 4 into your C:\Program Files (x86)\AviSynth+\plugins+ folder. 4. Copy all the files in folder 5 into your C:\Program Files (x86)\AviSynth+\plugins64+ folder.

FFTW Library files

If you’ve done the above correctly, skip this section. Probably the most confusing aspect of setting up, especially for QTGMC, is the bitness of the FFTW3.DLL and libfftw3f-3.dll files and where they reside. The 32bit versions are 2336KB and must be in the C:\Windows\SysWOW64 folder. The 64bit versions are 2708KB and must be in the C:\Windows\System32 folder. Yes, those locations do seem the wrong way round but they are correct. If you’re so inclined, here’s the explanation. Here are the FFTW files (they are also included the above package). Download and unpack the zip to get access. Annoyingly, both versions have the same name, hence the reason I’ve given the file sizes so you can work out which one is which. Those of you with an attention to detail will observe that the two files appear to be exactly the same. That’s because they are! By some twisted logic, libfftw3f-3 is simply a renamed fttw3.

Dependencies

As you have probably cottoned-on-to, some filters/plugins for AVISynth rely many other plugins which you may not actually use in a script. QTGMC is a good example. While in the script we will only use “QTGMC”, there are many other “hidden” plugins required to make it actually work. They are in folders “4” and “5” of my install process above. So, if you are trying to use a filter and get error messages, go onto the AVISynth site and search for the filter description. The documentarian will show the required dependencies, which you will probably have to download separately and place into your plugins folder to make the filter work.

Virtual Dub Setup

Set up Virtual Dub, as per my instructions here. VDub is used to open, or display, the AVISynth AVS scripts that you create. Other programs can also open AVS files, including advanced AVISynth programs such as AVSPMod and some media players such as Media Player Classic. VDub allows you to edit the AVS on the fly to adjust your AVISynth output. You can then perform further operations such as editing/trimming, cropping, resizing, and export to MP4 all from VDub. Or you can Losslessly export the video so that it can be edited further in a more fully-featured video editor.

Updating AVISynth

AVISynth is updated occasionally. To update your installation, the recommended procedure is to simply replace the avisynth.DLL with the new version as opposed to reinstalling. This VH post refers.

Using AVISynth

You don’t actually open AVISynth as a program. What you do is create a script (an AVS file), and when you open that script in VDub, the script will use the parts of the AVISynth installation and plugins it needs to process, as per the filters you set up (such as QTGMC) and then display your filtered file in VDub. You can then do further editing or save it into another format for further editing in an external editor, or for distribution in, for example, MP4. For example, my typical workflow for a VHS capture is: • Capture with AmarecTV, • Create an AVISynth script with the captured AVI file (as I show below) to deinterlace with QTGMC, • Open that AVS file in VDub and apply other filters such as basic cropping, resizing, colour and level adjustments, • “Save As…” the video into AVI format, • Import that AVI into my video editor for titling, fades, further cropping and editing and exporting to my final format such as MP4.

Typical AVISynth+ script to run QTGMC

A “script” is actually just a plain text document, written with Notepad, but saved with the AVS file extension instead of TXT. A typical AVISynth script which uses QTGMC to deinterlace an AVI video and double the framerate follows, with explanatory comments following. SetFilterMTMode ("QTGMC", 2) AviSource("H:\racwa\aeroclub-int.avi") ConvertToYV12(interlaced=true) AssumeTFF() QTGMC(preset="Fast", EdiThreads=8) # set EdiThreads to half the system cores you have Prefetch(24) # set to the number of Logical Processors in your CPU Explaining the various parts: SetFilterMTMode ("QTGMC", 2) Tells AVISynth what multi-threading mode to use. AviSource("H:\racwa\aeroclub-int.avi") Tells AVISynth what “source filter” to use to open the file, and it’s location. Always wrap the full name in quotes. If the AVS file is saved in the same folder as the video file you’re processing, you don’t need the drive and parent folder in the name. Tip: use the Windows RC menu “Copy as Path” item to copy the complete file name, then paste it in. There are other source filters for opening other types of files eg MPEGs, MOVs, MP4s. For example, you cannot use “AVISource” to open an MP4. Other source filters are shown lower down this page. ConvertToYV16(interlaced=true) Converts file to the required colour space. AssumeTFF() Tells QTGMC what the interlace status of the file is. Almost all analogue captures are Top Field First; DV files from DV camcorders are almost always Bottom Field First, so if you’re working on DV, use “BFF”. In any case, if you get it wrong, you’ll notice forward- backward-forward movement when you step through the video frame by frame in VDub. Simply change to the other option. QTGMC(preset="Fast", EdiThreads=8) Tells AVISynth to execute QTGMC using the “fast” preset and to use the extra threads in your CPU to speed up processing. Set the EdiThreads to half the system cores you have (Task Manager>Performance has the number of cores in your CPU). QTGMC defaults to double-framerate mode; it splits each field into a frame. Prefetch(24) Tells AVISynth to use the available cores in your CPU to speed up the process. Set it to the number of Logical Processors in your CPU, available from Task Manager. If you have issues, reduce the number progressively. You then save the script text, using a basic editor such as Notepad, as a text-format file with the AVS file extension. All that is then necessary is to open the file in Virtual Dub and the result (meaning your original file, after processing by the script) will be displayed. Give it a go. Copy the text of the script, paste it into a TXT/Notepad document, change the name of the file to be opened and save the file as an AVS file. Here are some sample full-interlaced files for you to experiment with (not all files have full-interlacing; for example, converting telecined movies to progressive video require different treatment. See my page on Deinterlacing for details).

AVI

• f18 • aeroclub

MPEG 2

• aircraft MPEG2 (requires a different source- opening filter) Open your AVS file in VDub and, fingers crossed, you’ll shortly be looking at a crisp, smooth, deinterlaced AVI. You can now continue editing it, perhaps trimming and deleting parts, and/or exporting it in whatever format you wish to either continue editing elsewhere or save as an MP4 for distribution. If you have problems, run the AVISynth Info tool, which will report any issues with your installation.

File-Opening / “Source” Filters

There are many different file types and AVISynth does not have a common source filter which will open them all. To that end, here is a list of filters that will open most file types. All of these sources work with 64bit; some don’t work with 32bit. For files with no audio, the a = and AudioDub(v,a) lines can be commented-out or deleted. Copy the source filter you need from this page and paste it into the top of your script. Occasionally, a particular source filter doesn’t open the file properly. For example, the field order might randomly swap. If you’re having problems with a file not opening as you would expect, try changing the source filter. An example of this is in this post, and another in this post on VideoHelp..

AVI (32 and 64bit)

AviSource("H:\Video Tapes Albums\Video Album 2 Tape A3\Leroy.avi") no need for a separate audio source filter.

MP4, AV1 (32 and 64bit)

v=LSMASHVideoSource("F:\Flying\F18\F18 Movie - Fish\Sting of the Hornet.mp4") a=LSMASHAudioSource("F:\Flying\F18\F18 Movie - Fish\Sting of the Hornet.mp4") AudioDub(v,a)

MPEG2

FFmpegSource2("F:\Family Videos\2004\birthday.mpg", atrack=-1) This will extract the first audio track in the file. When saving the video in VDub, very fast encoding into AVI or H264.

MPEG 2 in MKV

aud=ffaudiosource("Filename.mkv",track=-1) vid=ffvideosource("Filename.mkv", track=-1, seekmode=1,fpsnum=30000,fpsden=1001) audiodub(vid,aud) Note TDecimate did not work correctly with ffvideosource on an MKV(AVC)

MPEG 2, VOB (32 and 64bit)

Note: m2ts out of sync 64bit on some files v=ffms2("boating.mpg") a=LWLibavAudioSource("boating.mpg") AudioDub(v,a)

MPEG2 (32 and 64bit) , MKV, MOV, MP4, FFV1 and

others

v=LWLibavVideoSource("sample.VOB") a=LWLibavAudioSource("sample.VOB") AudioDub(v,a) Magix NLE will not open the audio in AVIs created from MPEG 2s using this filter.

WMV

From here: https://forum.videohelp.com/threads/419043- Avisynth-and-WMV-s-keeping-A-V-in- sync#post2782791 WMVs can have variable video and audio framerate causing sync issues. This source filter code mitigates this. fn = "D:\filename" #without the extension vfn = fn+".wmv" afn = fn+".wmv" a = FFAudioSource(afn).EnsureVBRMP3Sync() FFVideoSource(vfn, fpsnum=30000, fpsden=1001) Preroll(60) AssumeFPS(30000, 1001) AudioDub(a) Other file types (this is the least preferable source filter because it may not be frame-accurate) DirectShowSource("title00.mkv")

AVSIs

Most plugins are in the form of DLLs, but AVSIs are also plugins. They are basically autoload files, meaning they that run as soon as AVISynth starts. AVSIs are generally not downloadable as a file. They may be presented on their download page as the actual text characters, so if you need to find or install an AVSI, copy all of the text given into a Notepad text file and save it, then change the file extension to AVSI. Ensure you have Windows set to show file extensions. An example of a “create your own AVSI” for the Chromashift plugin is here. When you click on the link to the AVSI at top right, all you get is a bunch of text. Simply copy all of that text into a text file, then rename it with the “AVSI” extension ie ChromaShiftSP.AVSI, and then you will have your AVSI to put in your Plugins folder. As an alternative, you may find the already- constructed AVSI on Github, Doom9 or other websites. Some common AVSIs are in the filter folders above.

AVISynth Tricks and Tips

• On Windows, there should be a RC option for copying the file name “Copy as Path”: very handy when copying your video’s filename into a script. • To quickly access and amend your script in VDub, after you have opened the AVS initially, go Tools>Script Editor. The script editor box will open so you can edit your script. Then, to run the amended script, click anywhere in the editor window then hit File>Save and refresh… You can set up keyboard shortcuts for these (I use F12 to open the AVS, then F5 to run the amended script). This feature is great for quickly assessing adjustments to values. • Text case is not important although the convention is to use the case as shown in the AVISynth wiki. • To “comment-out” or disable a line of text in the script, place a # symbol at the start of the text you want to comment-out. The # will also work on text part-way along a line. For example: Prefetch(24) # use the number of logical processors from Task Manager means that AVISynth will run “Prefetch(24)” but not run the text “use the number of…”. This is good for putting comments after the actual code on a line. You’ll see I’ve done this in the sample script for the EdiThreads and PreFetch. • To comment-out a number of lines, at the start of the line to be commented-out put in /*. At the end of the final line to be commented-out, put */. For example: /* this is a block comment; we can write a lot here and also comment out multiple lines of code SubTitle("Hello, World!") - this code won’t be processed because it is in a block comment */ A simple way to remember which order the / and * are in is to look at the keys on the numeric keyboard: to start the comment area, use /* (left to right), to close the comment area, reverse it to */. • If you want to wrap your code to the next line instead of having one massive long line of code, insert a space\. This will allow you to wrap the rest of the code to the next line. I find this is helpful in situations such as subtitles for Stack arrangements:

Scenarios

After going through all of that, you’ll want to start using AVISynth to actually achieve stuff. I’ve made up a collection of scenarios which you might come across and where AVISynth excels here: AVISynth Scenarios

Further Resources

The Videohelp forum has a number of very knowledgeable users of AVISynth. If you have any issues or questions on the use of the various filters/plugins, I suggest you post a topic there to seek help. If you have any issues with the setup described here, please send me an email at the address on the home page.