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How To Fix Video Interlacing in Your Movie Files On the Fly

By Will Greenwald

Several precautions you can take to reduce the effect of interlacing, either when converting your video or during playback.

Have you ever watched a video on your computer and noticed the picture breaking up into misaligned arrays of horizontal lines whenever there's a lot of motion on the screen? It's called interlacing, and it can ruin an otherwise well-encoded and -rendered video.  
 
Video interlacing is the technical relic of video production decades ago. From the early days of video, interlacing was used to make footage seem smoother without requiring more information to be transmitted. Each full frame of video is split up into two fields of alternating lines. Instead of displaying the full frames in their entirety one after the other, the two fields of each frame are drawn in succession, producing a consistent image while appearing smoother than it would look otherwise. Progressive scan, which involves drawing the whole frame without breaking it into fields, can produce higher resolution video at the same framerate but requires higher bandwidth. While that bandwidth is readily available now and most HDTVs are 1080p (progressive-scan screens with 1,080 vertical lines of resolution), interlaced video remains an issue with a lot of media. 

 
feature deinterlacing filters during playback. They're disabled by default, but you can access them by going to the File > Preferences > Advanced menu or right-clicking the video respectively. The Bob and Linear deinterlacing options can often produce very good results, but they require more processing power than other options. You should only activate the deinterlacing filters if the video shows a lot of combing. If you try to deinterlace a video that's not interlaced to begin with, it can waste processing power and look strange.  
 
Ideally, you want your videos to not be interlaced in the first place. This is an easy fix when ripping DVDs with Handbrake. Click on the Video Filters tab and select one of the options under Deinterlace. Fast is the quickest but least effective deinterlacing filter, while Slower generally produces the best results.  
 

100fps.com has an effective and free technique. First, you'll need to download and install  VirtualDub, a free video processing program, and Avisynth, a video post-production tool. Second, you'll need to create a ".avs" file telling VirtualDub and Avisynth to split up the video into individual fields; the exact method is outlined on 100fps.com. 
 
Finally, all you have to do is download and use the Deinterlace - Smooth filter on your video. You might have to play around with a few of the settings, but eventually you'll get a smooth video with no irritating horizontal lines messing up the motion on the screen.