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  • Open Any File with AVISynth

    AVISynth is a really cool utility, yet it seems very few people are using it! The reason many haven't started is probably not because AVISynth is hard to use, but basically because they downloaded it, double-clicked on each file to try and get it working only to find that it doesn't seem to do anything!? So perhaps it may be a good idea if I explained what AVISynth does and how it can be used!

    What can we do with AVISynth?

    Lets say you downloaded a weird format video file and wanted to edit it with VirtualDub or convert it to Mpeg with Panasonic Mpeg encoder or with some other Mpeg / AVI etc., encoder. It would normally be impossible to do this because neither VirtualDub nor Panasonic Mpeg Encoder supports this format. Windows Media Player, however, is usually able to play just about any file with no problems. If it cannot play it there will usually be a codec you can install that will allow Media Player to do so. Well, if Media Player can play it usually AVISynth will let you open it in whatever application you need! This even applies to Mpeg-2 files! Yep, that's right! If Media Player can play your Mpeg-2 file then AVISynth will let you open them in almost any video editing or converting utility!

    But that is not all! Before it sends the video to be opened in VirtualDub (or whatever application you want) it gives you the option to do all sorts of things to the video! You can resize it, crop it, sharpen, blend, separate interlaced fields, delete frames, duplicate frames, add 3:2 pulldown, reweave interlaced fields, bob deinterlace, convert between YUY2 and RGB and a whole host of other interesting and useful features!

    How does it work?

    AVISynth acts as a go-between between your video file and any video application you wish to use. You install AVISynth by putting a small .dll program in the Windows System folder. This is almost like a Windows upgrade, it then intercepts all files opened that are called something.avs and then runs them through AVISynth. In turn AVISynth decodes them using Media Players codec's and sends them to the application you were opening them with - cool huh!

    Basically to do this you need to write a simple text file saying what file you wish to open (just like making a .lst file for Mpeg2avi) and rename the text file with an *.avs extension. Then, when you open this file in VirtualDub or Panasonic Mpeg Encoder (or whatever application you are using) AVISynth will take over and covert it for that application.

    Don't worry, it may not sound too clear to you right now, but its not hard and after you have followed my step-by-step examples you will be able to set it up and open any file in seconds. So without further delay lets get started.


    Lesson 1: DVD to AVI with AVISynth!

    Since we are Mpeg-2 obsessed at Digital Digest, what better than to show you how to open a DVD in VirtualDub. As you know VirtualDub doesn't support Mpeg-2 and cannot open or edit Vob files...we will soon change that!

    Can you open DVD or Mpeg-2 in Media Player?

    As I mentioned, AVISynth can open just about any file that Media Player can handle. But if you cannot open a Vob file in Media Player then you will need to install the Ligos and WinDVD codec's first so Media Player can. This is easy enough to do:

    You will need:

    Ligos Mpeg-2 Filter and WinDVD Audio Filter

    Download the above files and drag the something *.ax file over the RegDrop program and your files are registered. Like this:

    Note: the picture above is only an example of what you do, you do not need any or filters.


    Installing AVISynth

    Before I start here are the things you will need:

    AVISynth 1.0 Beta 3

    VirtualDub 1.4c

    After you have downloaded and unzipped AVISynth you should end up with a folder containing the following files:

    Cut and paste the first file called avisynth.dll into your C:\Windows\System folder. Then double-click on the install.reg file and the program will be installed. To uninstall it double-click on the uninstall.reg. To uninstall you can also delete the avisynth.dll file from your Windows\System folder but that's up to you.

    Cannot find the DLL file?

    If you cannot find the avisynth.dll file then its very likely that windows is hiding it from you. Windows hides all files that have the DLL extension. in case you accidentally delete any of them and cause windows to become corrupted! To view all files you should open windows explorer and go to:

    View > Folder Options...

    Hit the View tab button and select the option: Show all files

    This will allow you to see the avisynth.dll file and place it in the Windows\system folder :). If you are worried about people accidentally deleting DLL files you can turn the 'hide hidden or system files' option on.


    Creating an AVS File

    Okay, all the hard work is done! Make a folder on your main drive (usually C:) and put the Vob file you wish to open inside it. I have called my folder vobfiles and the file I'm going to open is called VTS_01_01.Vob.

    So open windows notepad (or any text editor) and type the following into it:


    As usual the colours are mine and here to help explain this line means. The DirectShowSource is a command that basically means open anything using Media Players codecs. Then, in brackets and quotation marks, we say what file we wish to open. In this case I said look for the Vob file in the folder C:\vobfiles and called VTS_01_01.Vob.

    Save it!

    Anyway, save the file as whatever you like but put the extension. *.avs on it instead of .txt or .doc etc. I'm calling my text file movie.avs. So when I choose Save in notepad I will type the filename "movie.avs" make sure you use quotation marks (" ") to force notepad to save it as avs instead of txt. Again, it will not work if the text file is called movie.avs.txt or movie.avs.doc or something like that.


    Opening the File in VirtualDub

    Okay, time to open our Vob file. Were are going to use VirtualDub, but, as I said before almost any program will open the avs file. Load VirtualDub and go to:

    File > Open

    Find the avs file you made:

    And this is what you get below - VirtualDub reads it just like it was an AVI file!

    That's right! Has he discovered how much his son likes apple pie, or has he just learnt about what AVISynth can do? You decide!

    AVISynth doesn't offer the ultimate solution for DVD conversion. For one thing it cannot handle subtitles or multiangles directly like Flask Mpeg can. Also, if Media Player cannot open a Vob file or if it cannot play the sound you will not be able to get it in VirtualDub either! All in all VirtualDub may not be as fast or versatile at manipulating Vob files another dedicated program such as Mpeg2avi because it was designed solely for that purpose. Nevertheless, have a play and see what you can come up with :). But don't forget, AVISynth is not just for opening Vob files it can handle almost any file.


    Advanced avs Files

    That introduction tells us the basics, but there is so much more AVISynth can do with these files before they are given to VirtualDub or whatever application you may want to open them in. I will not explain every possibility because that's a mammoth task. Instead, I will explain how to use some of the basic commands and then you will know how to design your own better.

    Opening ASF and MOV files

    Its not an exact science but you can often open many MOV or ASF files. Both MicroSofts ASF and Apples QuickTime are generic codecs. This means that different codecs are used for both ASF and QuickTime files but they are still called ASF or MOV. What I'm trying to say is you can open some but not others. To open them you usually need to specify the Framerate. You do that like this:


    Opening Multiple Files

    If you want to open lots of files so they open as one single file like making a mpeg2avi .lst file, all you need to do is add a plus (+) sign and tell it which files to join. For example, instead of this in out text file:
    We could have this:

    That would tell AVISynth to open vob files: 01, 02, 03 & 04 as though it were a single file.


    Other File Opening Options

    DirectShowSource("filename&location"). As we have already seen, this command will open just about any file that Media Player can play. This includes audio files such as WAV, MP3 etc. For example, you could open just about any audio file in an audio editing package such as SoundForge even if SoundForge didn't support that format. Just make an avs text file like we did before and open it in SoundForge the way you did VirtualDub. Unfortunately ASF files do not work correctly and look upside down and ma not have any sound :(.

    There is also an experimental Vob opening command called:

    But this may or may not work for you so you may wish to swap DirectShowSource and VOBVideoSource.

    AVISynth also offers other AVI opening commands. The reason for this is because handler may be able to open a certain file type better or process it faster, or may be supported better by the application AVISynth is opening it in.


    So between this lot you should be able to open almost anything.

    This command is designed for opening wave files.


    Video Editing Commands

    Once you've decided how you will open the file you can command AVISynth to do stuff with them beforeit sends them to the application you wish to open it with. This is very useful if you need to crop or resize or something like that but the application you want to open it in doesn't let you. All this crap may sound a little like we are about to learn a programming language, but really its just a matter of listing what things you want done. For example, say we want to open the file but make it half the size it was originally, we could put:


    That's all we need to do! Save the avs text file as usual and open it in VirtualDub to see how it looks. You will find that it opens the video file but at half of its original size!

    Okay, lets add to that. Lets say the application you wish to open the file in prefers the RGB AVI format but your original file is in YUY2 format we could put:


    This time it will open the file, half its size and change the format to RGB. Notice also how I have just added this new command to the last one like a shopping list :). Each command can usually be just stuck underneath the last and AVISynth will perform them in that order.

    File Command Order

    The order in which you ask AVISynth to perform commands can affect both what the final result looks like and how fast the option is completed. For example, say we opened a huge 720 x 576 pixel DVD file. We want to sharpen the image and resize it to 352 x 288 according to a bicubic resize. We could do it like this:


    But that is a slow way to do it because this way the sharpen filter comes first in the list. Obviously it takes longer to sharpen a 720 x 576 image than it takes to sharpen a 352 x 288 image! So instead its better to do it in this order:


    This way the image is shrunk first and then sharpened after.

    We can also repeat effects. For example, if you wanted to make it twice as sharp you could do this:


    Note: Not all programs will be able to handle every option or some repeated sequences of options so its trial and error. For example, VirtualDub will often crash if you try and feed it a Vob file with multiple AVISynth alterations added it it.


    Frames & Fields

    I couldn't finish this article without saying a few words about AVISynth's Field and Framerate commands. So here are a few that should help you get started.


    This is one of the easiest ways to solve those NTSC interlace problems when opening the file in an application that cannot deinterlace it. You could use:


    Simple as that! You may be interested to know that Bob is the method that PowerDVD uses most often to solve those annoying interlace combing problems. This will fix all interlaced files that look corrupted like the following picture:

    For more details on interlace problems you could check out my article on 'NTSC / PAL & Interlace'.



    Another handy little feature that lets you separate the top and bottom frames of an interlaced picture. If for example you will be resizing an video file from 576 pixels high to 288 pixels high or lower an easy way to both speed things up and completely solve all interlace problems without any loss of detail s literally to separate fields. This can be done thusly:


    This will double the amount of frames in the movie because its now giving you frame 1 (top field) frame 2 (bottom field). So a 30fps movie becomes a 60 fps movie. So you may want to use the SelectEven or SelectOdd commands to fix this. Either command will select every other frame in the file. So select odd may just leave you with only bottom or top video fields. To use it just add SelectOdd to the list, like this:


    This will make the 60 fps back into 30. All these options shouldn't take very much processing power because AVISynth is only taking the information from the file in a certain order, it doesn't need to do heavy calculations on it.

    You may be wondering why your movie now looks like a pancake! This is because it only has half the lines it did originally. Like I said you intend on resizing the movie anyway and this solves both interlace problems and cuts down on CPU power because there is of a picture to resize :). To make the final image complete we simply use a BilinearResize option like this:




    Want to Learn More about AVISynth commands? Here they all are! Just click on each one and it will take you to the info found on the AVISynth's official Webpage:

    Duplication of links or content is strictly prohibited. (C) NICKY PAGE 2000