Tag Archives: deinterlace

The Progressive Society – Pt 2

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Right. That’s it. I’ve had it with interlacing.

It was a cool trick back in the days of Ye Olde Cathode Ray Tube and valves, but interlacing is hanging around like a bad smell in these days of LCD and Plasma displays.

  • Is this web page interlaced? No.
  • Are any computer screens interlaced? No.
  • Is a video projector interlaced? No.
  • Is your TV at home interlaced? Well..

Maybe yes, if you haven’t gone flat panel yet (guilty m’lud), but you’d be hard pressed to pick up an interlaced TV set of any sort of quality at your local TV store.

And herein lies the rub: putting interlaced video onto a progressive scan display device LOWERS the resolution. Either by quite a bit (25%) or by a lot (50%). A lot of the cheaper LCD TVs simply chuck out every other field and double up what’s left. That’s why it’s cheap – or ‘Good Value’ and why TV looks all fuzzy and horrible. Higher end sets do some magic and scaling through hardware, but it’s not quite that beautiful astonishing look you get when you work out how to feed a true progressive source into a progressive screen.

But that’s exactly where television is moving. People are consuming audiovisual entertainment in places other than in front of the family screen. Web video, downloaded movies and the like are becoming the norm.

Now this is why I’m all hot under the collar: I’ve been producing progressive scan video for ‘data delivery’, and recently had cause to shoot a job in interlaced DV. Of course, it had things like captions in it, some graphics. Looks great on a PAL CRT monitor. But it was detstined for a life on an intranet, and being played from within PowerPoint. It needed to be deinterlaced (the horror of the Mouse Teeth is still in working memory). And behold… the zing, the sharpness, the ineffable vim of the whole thing has been diluted.

When web movies were 320×240 and MPEG1 files for PowerPoint weren’t much larger, the loss of resolution through deinterlacing wasn’t noticable, but mark this well: Web video has supersized. Measuring between 512×288 right up to 1280×720, there isn’t enough scaling down to hide the deinterlacing softness under the carpet.

So that’s it. It’s official.

I’m not shooting another frame of interlaced video.

The Progressive Society – Pt 1

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I’m wrapping up a little trio of edits which involve bringing together existing footage from a variety of not-exactly-optimal sources (odd MPEG1 files, WMVs, some DV, all 4:3) with some professionally shot 720p footage. Thank goodness for FCP’s multi-format timeline (and MPEGstreamClip for converting virtually anything into anything else).

Of course, I’ve been editing 720p pretty much exclusively for months now, so when some DV footage needed to be inserted, I faced… Cue dramatic chord: The Curse of the Mouse Teeth From Hell.

I guess that if you’ve only ever edited DV footage, especially if you edit your own material, you’ll just shrug your shoulders and wonder what I’m on about. But if you’ve ever dropped in a bit of NTSC into a PAL timeline, or scaled up some DV, you’ll have seen those unsightly blocky edges that suddenly appear around anything that moves. As if some monster rat has been nibbling away at your video.

We’re not talking that blocky pixels from overworked compression or a bad tape dropout, we’re talking bobbly edges on things that move fast in frame. It’s caused by the interlaced video being stretched in a non standard way. For example, NTSC being stretched from 720×480 to 720×576, or PAL being stretched up from 720×576 to 1280×720. The on-off-on-off cadence goes to pot, and the fields are chosen in a ‘knit 3, pearl 7’ way, and you get… video that’s been attacked by monster-mice when anything moves.

Well, all this rodentry is only mentioned because I found a quick and dirty fix. Whilst not exactly perfect, it doesn’t rely on a quarter of a million quid’s worth of Snell & Wilcox Alchemist either.

Get the properties of your upscaled and interlaced footage, and set the clip’s properties to a field dominance of none. It gets scaled progressively, gaining some softness and quasi motion-blur at the expense of the crisp video like motion.