Getting Started with Avisynth

Turn your PC into a video powerhouse

Avisynth

Conventional wisdom tells us that to be truly useful, computers need to be tamed to work the way we work, not the way they want to do things. Following this philosophy, movie-editing software like Apple's Final Cut Pro and Adobe's Premier emulate reels of celluloid that you can wind through to find your edit points. Unfortunately, this emulation eats up computer resources. Dispense with it, and there's a great way you can do movie editing without having to lash out on a quad-core machine with multi-gigabytes of Ram.

The secret is a software application called Avisynth. I mainly use it for cleaning up films recorded off the telly. But Avisynth is perfect for taking control of your own home-video footage, perhaps turning it into DVDs for the family time-capsule. Or whatever.

Of course, professional editing software offers non-linear editing (NLE) - the ability to access frames at random and do virtual cuts without modifying the original clip - and a feast of instantly deliverable transitions - dissolves, wipes, and so forth. Not stuff you'd expect to do on an 800MHz single-core Celeron system. But guess what? With Avisynth, yes you can.

Because it's not NLE and transitions that eat up computer resources, it's that pretty interface emulating a pre-war Moviola reel-to-reel editor. Take that away, and what you have got is something that looks like this:

video = MPEG2Source("Clip1.d2v", cpu=0)
audio = NicMPG123Source("Clip1 DELAY -746ms.mp2")
AudioDub(video, audio).DelayAudio(-0.746)
Trim(29, 162052)
Dissolve(Trim(0, 28648) , Trim(35426, 162023), 5)
Trim(0, 61566) ++ Trim(68844, 155241)
Dissolve(Trim(0, 98264) , Trim(105041, 147964), 50)
Trim(0, 141032)

Yes, it's a script. The bad news is the only thing in the world that can understand it is Avisynth. But now for the good news.

1. Avisynth is free software.

2. Avisynth runs on 98 per cent of the the world's computers. That's the upside spin - "runs only on Windows" would be the pessimist's version.

3. That eight-line script is all you need to (in this case) turn a TV recording of a movie, with junk at the beginning and end, and three ad breaks in between, into a continuous presentation that wouldn't disgrace a small cinema. By "continuous presentation" I don't just mean ad removal, I mean a proper rebuild of the movie that totally conceals the fact that ads were ever there in the first place.

There's more good news. With a few extra lines of script we can seamlessly eliminate the tendency some TV channels have of ruining the finale by sliding in visuals announcing what's coming next and/or talking over the closing music. We can even blot out - and in many cases virtually make invisible - those eye-grabbing logos that channels like More 4 and ITV 2 stamp on every frame of the movie footage they transmit.

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