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Method 2: Editing DVD footage directly.

You have avs files which decode and filter DVD footage all ready for editing... but there's a problem.

Many video editing applications do not like .avs files by default. Some programs require plugins and other programs have to use what is known as an 'avi wrapper' to make the programs read the avs files. Which method will depend greatly on your editing program.

a) Adobe Premiere - Premiere can use .avs files directly thanks to an import plugin which is included in the AMVapp.

b) Programs with no other .avs support - In order to use .avs files in programs like Windows Movie Maker, Vegas Video, Adobe After Effects, Ulead Movie Studio Pro and so on, you need to use the AviSynth Virtual File System.

But, let me make one thing clear. This method is NOT recommended. Making lossless clips is far more stable, and editing will be faster. This method uses lots of ram if you are using several different scripts at once, so coupled with the fact that most video editing software uses lots of ram anyways, this can start to get bogged down very fast.

Adobe Premiere

To edit with your avisynth files in Premiere, you will need to download the latest Premiere Import Plugin. If you have downloaded and installed the AMVapp then you should already have it installed. One you have this installed, it will allow you to open AVISynth (.avs) files in Premiere. Note that as of Premiere Pro CS5, this plugin NO LONGER WORKS.

Quality, Stability and the Premiere AVS GUI

The Premiere plugin, developed by fellow amv-ers, contains a GUI which can change the quality of the footage you import into Premiere and it can also set up memory options to make AVS useage more stable.

When Premiere asks for a frame which is a different size than your source (preview window, timeline or exporting at a different size) the avs import plugin has to resize it. To do this there are 4 different resizers that you can choose in the GUI:

Premiere AVS Plugin GUI

As you can tell by the descriptions, low-quality resizers are fast and high quality resizers are slow. So what I recommend is setting the algorithm to Nearest Neighbour as this will ensure the timeline thumbnails and monitor previews will be the fastest they can be. When you export, however, you will want to change this to one of the other settings as Nearest Neighbour is poor quality.

The slowdown with the better resizers isn't that much though. With a quick 1000 frame rendering test it took 31 seconds with Nearest Neighbour, 34 seconds with bilinear, 36 seconds with Bicubic and 37 seconds with lanczos3. So, if you don't mind that amount of increase then you can keep it high quality all the time.

The right hand section of the GUI changes the Set Memory Max preferences in avisynth. Avisynth is not usually designed to process multiple avs scripts at once and as a result the memory can get used up really fast when processing multiple scripts. This can lead to avisynth crashing halfway through a render. To avoid this you can set the maximum memory allowed by each script. This option currently only works with Avisynth 2.5+ (which comes with the amvapp). The default setting is 256mb but if you are using lots of scripts you may want to reduce this to avoid memory crashes. It's a tricky thing to set, however, as some scripts which have a lot of processing may need a lot of memory and could crash if you set it too low - don't go below 32mb unless you really have to.

Errors, bugs, limitations and other things to avoid

Using avisynth scripts in Premiere can be a delicate matter. There are a number of things you should be aware of when importing avs scripts into Premiere:

1) Check that the script works in VirtualDub. If you open a faulty script in Premiere you will just get a small 10 second clip containing an error message.

2) Make sure your avs script is creating an RGB32 output  By adding ConvertToRGB32() to the end of your script, you can make sure that the footage is in the correct format for processing in Premiere.

3) Don't slow down clips too much. If you slow down clips in Premiere to very slow speeds (like <10%) then it might crash avisynth when you try to export or reload your project. Do not do this. Either make a still and use that or if it crashes when applying lots of filters, try and pre-render the section with a lossless codec.

4) Do not change your script whilst Premiere is open. It probably won't crash but if Premiere is expecting a 1000 frame file and you change something and give it a 30 frame file then any clips that no longer exist in the new avs file will be converted to 1 frame empty clips. Also, if you change the frame rate Premiere will have to interpolate the cuts and this can be really inaccurate leaving you with clips from all the wrong parts of your source footage.

5) Look out for avisynth crashes. If avisynth crashes it produces a short error clip instead of the footage. This is bad because it means the frames that were once there are no longer there. Premiere will sometimes, seeing that the frames are not there, convert your timeline edits to 1 frame completely destroying your project. The trick to avoid this is to NOT SAVE if you see this happen. Close down premiere, check your avisynth scripts to see if they are working, check your memory max settings and try the project again. If it's been saved with 1 frame cuts then you will have to go back to an older save file to restore your project. This is why setting up a Project Archive is important - you can see how to do that in the section on setting up your Premiere Project.

Now that you've read the info and understand the issues it's time to see how to correctly set up your video project.

Frameserving Avisynth to Programs without .avs Support

This method uses what is known as an avi wrapper. Many programs, when you give them a file, expect it to have a header that they recognise just like an avi header or an mpeg header. AVS files, however, are just text files so they do not have the information many programs need.

There is a way around this though, using the AviSynth Virtual File System (included in AMVApp).

Before you start, you want to make sure all of your avisynth scripts are in RGB32 colorspace, because this is the colorspace that your editing program will probably be expecting. This should be the final line of your avisynth script:

ConvertToRGB32()

Now, assuming the AviSynth Virtual File System is installed correctly, when you right click on an AviSynth script, you should see two new items in the menu: Quick Mount, and Mount. Choose the quick mount option, and now your AviSynth script should turn into a folder. If you open up this folder then you should see your original avisynth script along with an AVI file. The AVI file will probably report a very large filesize, but this file does not actually take up any space on your disk, because it is a "fake" AVI file. That is, it is simply a virtual file which will allow your editing program to access the AVS script. Now if your AVS script contains any errors, then you wont see an AVI file here--it can't generate anything if your script is incorrect! If that is the case, then you need to right click on this folder and choose "unmount", then correct your avisynth script and try again.

Once you are done with that, you can import these fake avi files directly into any program which supports AVIs, and it will think that it is looking at a standard uncompressed AVI file.

This method for using Avisynth scripts should work as well as the Premiere method but it has not been tested as thoroughly, so proceed with caution. Like with Premiere there are certain things you need to be careful about when dealing with avisynth footage.

1) Check that the script works in VirtualDub or AvsP. If you open a faulty script you will just get a small 10 second clip containing an error message so you should test all scripts beforehand.

2) Make sure your avs script is creating an RGB32 output . Most editing programs process natively in RGB and it is best to give them footage in this format so you know that what you put in is what you will get out. You can do this by adding ConvertToRGB32() at the end of your script.

3) Don't slow down clips too much. Avisynth has been known to crash in Premiere when you do this so it is also likely in other programs too. Either make a still and use that or if it crashes when applying lots of filters, try and pre-render the section with a lossless codec.

4) Do not unmount your files or try to change your script while your editing program is open. This can only cause bad things to happen.

5) Look out for avisynth crashes. Avisynth has a tendancy to crash if a) the script has a bad filter chain or b) there are memory buffer issues. The former should be spotted in VirtualDub, and once the script works it should be left alone. The latter can be fixed by editing the "setmemorymax.avsi" file contained in your Avisynth 2.5/Plugins folder. The amvapp includes this script and sets the default to 64mb which means 64mb of memory is allowed per script used. You can reduce this as you please to avoid memory issues but don't make it too low.

Now you have your fake avi files ready, you can set up your video project.

August 2010