AMV Post Production - Introduction

You've exported your video from your editing package and now you want to compress it to distribute on the Internet? Good. However, don't jump in with both feet there are good ways and not so good ways of doing this. All of them work, but some are better than others.

Before actually compressing the file you have you will need to do the following things:

1) Remove any interlacing if you haven't done so already.

2) Filter out any noise and make the video easier to compress. (optional)

3) Resize the file to a distributable resolution and/or correct aspect ratio.

There are various tools that can do some or all of the above things:

Adobe Premiere - The worst choice. Its resizing sucks. Its noise filtering sucks. Its deinterlacing REALLY sucks. For post-production, it's the worst tool you can use. As recommended earlier, you should export either using your native codec or with a lossless codec such as HuffYUV or Uncompressed RGB and put it in one of the following...

TMPGEnc - Its resizing is average, its noise reduction is good and its deinterlacing is good but very slow and very fiddly to use. It also only operates in RGB and is only really useful if you want to make MPEGs as it's not very good for avi writing. A slow, arduous tool for what we need to do, you'd be better off with one of the following...

Virtualdub - Excellent resizing, good deinterlacing but bad inverse telecine, good noise removal. Also only works in RGB mode. The only advantage of virtualdub over the next option is the fact that its user interface is quite friendly but every post production operation you'd want to do in virtualdub can be done in the next option and lots lots more. Just follow the instructions and you should be fine :)

Avisynth - The king of post production and avi manipulation. Excellent resizing, excellent interlace removal with IVTC or deinterlacing, very good noise removal using either virtualdub or avisynth filters. This does everything and all in one place that can then work in either vdub or tmpg for your final compression.

Now I'm going to be realistic, if you have exported your video in RGB mode as described in the guide and it doesn't need deinterlacing, only resizing and compressing then there's nothing stopping you from using Virtualdub. It's easy. Of course, you should still read the post-processing sections for general advice if choosing this method as there are virtualdub versions of many of the avisynth filters and vice versa.

However, if you have a YUV file or you want to do either part 1 or 2 then you should use avisynth, cause it rocks. This is the method this guide will be using.

So in short, what we are going to do is make an avisynth script that

a) accesses your video,

b) removes interlacing if necessary,

c) reduces noise and makes it look good

d) resizes it.

This script can then be loaded into virtualdub or nandub for compression as DivX/XviD etc and also loaded into TMPGenc for compression into MPEG1 or 2.

For part a) and for basic use of avisynth please read the avisynth guides. To refresh your memory, here is how to import your video as an avisynth file:

Make a text file and rename it to something.avs and in the text file write on the first line

AVISource("C:/yourfolder/yourfile.avi")

AVIsource will work for all Video for Windows codecs and DV produced by the DV500 card etc. If AVIsource does not work for your file then you might want to try DirectShowSource instead. Please read the avisynth documentation about the details of DirectShowSource as it has some further options.

Note: if your source has been exported in sections then you will need to do:

AVISource("C:/yourfolder/yourfile1.avi") + AVISource("C:/yourfolder/yourfile2.avi")

With the source import line in the script you can then load the avisynth script into virtualdub, media player or tmpg and see the video file. By adding extra commands to the script we can do all of the filtering we need. At the end, you'll have one script which will do all your filtering and resizing which you can load into your compression program to make your compressed amv for Internet distribution or whatever.

Sound easy? :) It is, honest, and it's a really good way of doing things.

One last thing I will mention before we start doing things is to be aware of any colourspace changes you are making. For example, the export guide tells you that you can choose to export in YUY2 (yuv) mode or RGB mode. You will notice that most Avisynth filters work in YUY2 and this is ok, because that's the format used when you compress things too (provided you choose 'Fast Recompression' or don't filter in TMPG)

So, if you import an RGB file, you may have to add the line

ConvertToYUY2()

in order to do various avisynth filtering. This is ok as you have to convert to YUY2 eventually anyway (as that's the colourspace used for high compression codecs). If you need to do virtualdub filtering (you will be told about this in the pages to come) then you should do it before converting to YUY2..

If you have exported in YUY2 mode already, you can leave the ConvertToYUY2() line out of your scripts entirely and you should not use any virtualdub filters, TMPG filtering or include the line ConvertToRGB() because that is a wasteful conversion. If you need RGB operations, you should export from your editing program in RGB mode.

Annoying, I know, but as long as you keep track in your head of what conversions you are doing, trying not to do any where you don't need to then you'll be fine.

AbsoluteDestiny - October 2002