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The ExtraLives.org Guide to Capturing and Streaming Video (As Cheaply As Possible) Part 1: Deinterlacing

We're all about streaming video games here at ExtraLives.org. Still, this presents a bit of a problem-- most of the games out there are on consoles and are designed to be played on a TV. Unless you wanted to point a webcam at your TV and broadcast that (which is not recommended because it looks absolutely terrible), you'll need some way to directly capture video from a game system.

Well, I've been broadcasting junk online for more than three years now and I've wasted a lot of time (and money) on various pieces of hardware and software to do the job. It's 2012 now and I think I've gotten it down to a science.

There will be a bunch of different parts to this series but I'm going to start off with one of the most abundant (and easy to fix problems) I see with a lot of live video...

Interlacing (AKA: "My video is breaking into lines")

Link has two sets of eyes-- one for each sword.

Keep reading to learn more about interlacing and, more importantly, how to fix it. There are also pictures. Lots of them. Good times to be had.

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Interlacing is a phenomenon associated with standard definition video and CRT televisions. While these TVs are capable of displaying a video up to a resolution of 640 x 480, they only show half the lines of pixels possible and flicker between the two. This happens so quickly that you don't notice it on a tube TV. However, capture devices (and modern TVs) don't operate on that principle and look best when utilizing progressive video (where all the possible lines are shown at once).

If you plugged a game console outputting standard definition video into a modern LCD television, you'll notice the image isn't breaking up into lines. The signal being put out by the system is still interlaced but your TV is deinterlacing it all for you so you don't notice.

So… what does this mean for you and capturing video? Well, assume you plugged your composite video cable (the yellow one) into a capture device and began playing. Here's what you'd get:

Well... here's... what you'd get if you booted up Wind Waker. And went to Windfall Island. And stood right there in that specific place...

Doesn't look too terrible, right? Well, let's see what happens when you move.

Interlacing also makes pirates and random other NPCs appear.

Aaaand… you can see why interlacing is such a problem. Half of the pixels on that screen are for one frame of animation and the other half are for another. That's what it looks like when your video is interlaced and you're not doing anything to deinterlace it. When your game is in motion and things start to really move around, everything breaks up into lines. This looks TERRIBLE and, if left alone, can make your video pretty unwatchable.

Luckily, there are a few ways to fix this.

"If interlacing is caused by two rows of pixels flickering between each other," you may be thinking, "…why not just remove one of the rows (and half the resolution) entirely?"

This image is actually 639x479 instead of 640x480. Sticking it to the man.

Hey-- that looks a lot better! The interlacing is gone and everything is nice again.

So cutting the resolution in half does work. And, in fact, was how we took care of the interlacing issue for many of our early Marathons. With our two-screened racing setup, the game windows were often so small that you can't easily notice any difference between 320x240 and 640x480 video.

This is probably the closest race we've ever had. Too bad it's a mockup.

So, we've found the perfect solution to the interlacing problem-- just cut the resolution in half.

 …well… not quite. While this does remove the interlacing, it also makes everything look dramatically blurrier. This isn't so much of an issue on older games (most games on the N64 ran in 320x240 resolution natively, for example), newer games tend to suffer a marked drop in quality.

I can't tell if Tingle is any less appealing when he's all pixely.

Smaller details in games, like text, is especially impacted by a loss in resolution. In 320x240, small text goes from blocky and blurry…

I, for one, am looking foward to an HD Tingle in the next set of Zelda games.

To much smoother, sharper and more legible in 640x480.

So if cutting your resolution in half degrades the image quality, how do you deinterlace without ruining the picture?

Well, if you record or stream video with Xsplit (pretty much the defacto program now for livestreaming), it's an extremely easy fix. In Xsplit, all you need to do to deinterlace is right click your video capture window, click "Configure" and select the deinterlace option.

So you go from this:

Link was supposed to get a second Master Sword (and set of eyes) in that scrapped Wind Waker dungeon.

To this:

That Master Sword is actually a hockey stick. Link plays goalie.

With the click of this:

USB 2.0 ATV YEAH BOOOIIEEE ALL TERRAIN VIDEO UP IN DIS (Actually, it's a $6 EasyCAP).

So, please-- if you use Xsplit to broadcast, please, please, PLEASE deinterlace your video-- it takes virtually no effort and makes a HUGE difference. I'm not totally sure on the differences between standard and optimized deinterlacing in Xsplit so you may want to play around with that and figure out what works best with your computer and hardware.

Say you're using a different piece of streaming software without a deinterlace option and you don't want to cut the resolution in half-- what are your options? For this, I'd recommend downloading a program called VirtualDub. This program lets you capture video from your game system and process it to remove the interlacing. You can either record captured video directly from this program or screen capture it in a broadcasting program. Plus, it's worth checking out even if you do stream with Xsplit because Xsplit, as it stands now, has virtually no settings when deinterlacing (and, as you may have noticed, tends to make the image rather blurry in the process).

Download VirtualDub and click File and then "Capture AVI." Your game should show on the screen. Then click video, preview acceleration and select "Progressive - both fields."

Check out those interlaced seagulls in the background!

Whoa dude, that text in the back is, like, so meta, man.

From here, make sure "Preview" is selected and then click "Filter list…"

"General convolution" is a good way to explain my life.

And now you're presented with a bunch of different deinterlacing methods.

(Keep in mind you MUST be in "Preview" mode for any of these to actually take effect so if you're not seeing any change in your picture, double check "Preview" is selected and not "overlay.")

I never fiddled much with the field order. Wonder what that does.

Between these modes, we're only going to look at the top four. "Duplicate" and "discard fields" will generate results similar to cutting the resolution in half (which, as shown before, isn't quite the best way to go about this). The last two choices take the two different sets of interlaced frames and put them next to or on top of each other so you see two screens of your game at once-- probably not what you want.

So, say we want to deinterlace Link doing a backflip. Here's the image with no deinterlacing filter on, resulting in pretty obvious interlacing:

Shadow Link actually comes from Link's interlaced shadow. That's why he's evil.

Going from the list of deinterlacing options and starting from bottom to top...

Blend mode, AKA "Where the hell are my glasses?"-mode.

"Blend Fields" tries to blur the two interlaced frames together. The result tends to just look… well, like a blurrier interlaced image. The appearance of individual interlaced lines is less apparent but you still are able to make out two different frames on top of one another.

Not only does this look bad in still shots but it also looks crummy in motion-- blurring the two interlaced frames creates a ghosting effect so a lot of the image definition and detail is lost in motion.

Bob's my uncle... and a pretty decent deinterlacing method too.

Using the "bob algorithm" works a bit better. It displays each interlaced frame as its own individual frame. Remember how interlaced video is made of two half-size frames mixed together? Well, the bob algorithm takes each one and increases the size twofold so you're taking a frame of a lower resolution and blowing it up to a larger one. As a result, this tends to look a little blocky (though, because each individual frame of 640x480 interlaced video is made of two half-sized frames, using the bob algorithm to show each individual half-sized frame effectively doubles the framerate from 30 to 60). Your call on this one.

I kept looking for an ELO deinterlacing filter but no luck.

You've also got the "ELA algorithm." ELA stands for "Edge-based Line Averaging" which tries to average the two interlaced frames together to create one full-size frame. I've found that this generally retains detail but also has the tendency to make text look a bit wonky (check the "Defend" option and the rupee counts in the corner-- there are a lot of odd, misplaced pixels in and around it).

YADIF, man? YADIF? DO YOU DIF?!

Finally, there's the "YADIF algorithm" (Yet Another Deinterlacing Filter). I have no idea how this one works but I find it generally makes the nicest quality image. It's one flaw seems to be that occasionally some interlacing in certain areas (especially those with big color differences) tends to sneak through the filter. With live video (or YouTube) compression, this probably won't be too noticeable.

So select whatever filter works best for you (your choice may vary by game) and either record the video directly in VirtualDub or do a screen capture of the VirtualDub area in XSplit (or another broadcast program). Just a note: you may need to be in Windows 7 Aero mode to be able to capture video from VirtualDub (otherwise you may just get a black screen).

***Sometimes, for old games, interlacing actually breaks some graphical effects.***

Older games in the NES, Genesis and Game Boy games would often flicker sprites very quickly on the screen to fake transparency or to show more sprites at once than they could normally display. In these cases, interlacing via a filter or cutting the resolution will break these effects and only show half the frames of the animation. Check out the video below to get more details on this and, more importantly how to fix it. Make sure annotations are on.


 

Well, I wrote dramatically more on interlacing there than I ever thought I would… At least it has pictures! And Zelda! Everyone likes Zelda, right?

Anyway, the moral of the story is, if you're going to be doing any sort of video capture, either for recording or live broadcasting, YOU MUST deinterlace your video. Doing so increases the quality dramatically and makes it look much more professional.

(Of course, if you're capturing high definition video with component cables or HDMI, you won't experience any of these issues because those sources aren't interlaced. Still, this guide is about doing things on the cheap and high def capture cards will run you at least $100 or more).

Keep an eye on this guide as it expands into other areas like eliminating dot-crawl and obtaining the best quality from cheap-o capture devices. Plus, we'll soon have a series of recommendations for video capture equipment and software by broken up by price so you can begin streaming console games yourself for under $10.

 

Comments

Thanks for posting this Tim. When I was watching one of the recent streams and you were saying about interlaced I had no idea what you where referring to. You where like this looks gross and I was like huh whats so bad about it. (note: I don't see all that great and 480p and 1080p look the same to me.) I will have a play around with your tips when I decide to do another test record/stream. If you can write a guide on how not to have messy cables. As that puts me off using my capture card as I end up with what seems 40 feet of cables lol.

Thank you Tim! My friend and I have been thinking and wanting to do streams and such in the future, and this probably made part of it much easier (Never even heard of interlacing before). Same with the future parts of this guide. I just wanted to give thanks, and hope to see another marathon soon! ..or, you know, whenever's best. :D

Very informative and easy to read. Thanks!

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