What "i" and "p" mean in "1080i" and "1080p"

written by Kris Caballero (July 22, 2017)

Unless you're a broadcast engineer, a video/film editor, video duplication specialist, one who records video gameplay, a digital VFX artist or even a photographer, video resolution isn't something many people think about and often take it for granted. Most people care of the content being brought to us and in HD, only having to worry about not having any lag when streaming it. High Definition video has been available to consumers since the late nineties and early 2000s, and up to this day, many aren't familiar or even know the alleged "buzz words" thrown around when it comes to video. Worse, companies known to sell home entertainment packages and devices throw these terms to lure gullible customers into spending more than they should. If you're one of those tired of being hard-sold, welcome to VIDEOSOTROS! and this article is here to help talking about everything video.

Let's begin with the number: 1080. The number 1080 refers to the resolution of the video's height, but in no way does its height represent anything related to units of measure (i.e. inches, feet, yards, miles). This number indicates the video's vertical scanlines—strips of information that get electronically lit to draw an image. As many of you might know, the more scanlines the video has, the more information it presents, or in this case, details. More details translates to higher quality, more vivid and sharp video. Horizontally, 1080 is either set with 1440 scanlines, a horizontal resolution not used often, or more commonly, 1920 scanlines. Here's what the difference between the two looks like:

1080 and 1440 video size resolutions

As televisions have gotten more and more sophisticated, more thin and more "smart," it is getting very rare to find a TV that can't handle 1920x1080 high definition video (unless you shop on Craigslist or GoodWill). Many TVs have enough to project all those pixels, to bring you crystal-clear, HD video at the comfort of your own home.

That wasn't hard, so I'm guessing you're rushing to go to your favorite electronics store to pick up a TV, just like that? That salesperson working minimum wage will be glad to continue giving you the wrong information knowing he'll earn commission from every TV he sells. In other words, not so fast, as he'll throw in more terms to get you to buy from him even if it's not the TV you wanted.

Along with the scanline number, 1080, you'll often hear it paired with the letters "i" and "p." Now that you know a bit about the scanlines, what do these letters mean, 1080i and 1080p? That salesperson is hoping you don't know so they could use their persuasive demeanor to get you to spend, so here:

The letter "i" in 1080i means "interlaced," and "p" means "progressive." Any aspiring filmmaker out there who have proudly bought their first video camera are often familiar with these terms.

Interlaced video is brought out by usages of what are called "fields." There are two fields injected in interlaced video: ODD and EVEN. More often than not, these fields are indicated by letters "A" and "B"; In other words, the "A" field is ODD and the "B" field is EVEN. To 'complete' one frame of video, these fields flicker from ODD to EVEN, and does so at a very fast rate, or frame by frame. This means on one frame, you see "half" of the image, and the next frame, you see the "other half." In a sense, they're like venetian blinds flickering the complete image and doing so at every second at every frame. You know you point a video camera at a TV screen, and you notice the video on the TV flickers? Even yet, you also notice that some TVs show a huge black strip running up and down the screen? That's the screen flicker in compliance with any interlaced video it shows. Here's what I'm talking about:

This is one example featuring ODD fields, having 540 scanlines:
'ODD' fields of interlaced HD video

And one that has EVEN fields having the other 540 scanlines:
'EVEN' fields of interlaced HD video

HD video with 1080i were a thing back when tube plasma TVs where available in the markets (I own one branded by Sylvania). Most of these tube plasma TVs, or projection TVs, often showed silky-smooth 1080i video, whether it's a news broadcast or a TV show. In fact, 1080i video is still, and often, featured on prosumer video cameras and DSLR video. Why not 1080p video? Let's talk about that next:

The "p" in 1080p means "progressive." Progressive video is very much video...in full frame—no fields, no flickering. It is the full capture of the image, featuring wonderful motion and strongly recommended when editing for online broadcast or even [fast-motion] sports. Depending on the TV brand and its features, you can tell progressive video often shows smooth motion, usually at 60 frames a second (we'll talk about frame rates on our next Talk), and cinematic motion when shot at 24 frames a second. Nevertheless, if you look closely, you see nearly no flickering in the video and features full-frame goodness.

Because online production continues to grow at an enormous rate, progressive video is the go-to without worries on flickering images, resulting in jagged edges in the video. Eliminating those jagged edges from interlaced video requires deinterlacing, and depending on the software you use, some are able to pull it off cleanly, while some softwares do a terrible job at it. Watching it online, the jagged edges can be very distracting and unpleasing to viewers. When captured and recorded for online broadcast, this is generally how it looks like:

A screenshot of interlaced video via 'Emeril Live'
NOTE: I couldn't find an interlaced HD video in our library so I settled with an old recording of Emeril Live in Standard Definition (4:3 at 720x480).

If you look closely, you can see the mesh of the fields on Emeril's coat. This is because the software did all it could to combine both fields, but not good enough, resulting in this. It's very common, which is why some softwares have the option to blend fields/deinterlace. Again, depending on the software, some do a better job than others. It's all trial and error, if you've got a ton of time on your hands.

Why 1080p Isn't Often Available to Consumers

Today, lots of marketing experts wrongly use the term 1080p to promote their product(s) into thinking that it can handle and show full 1080p video. The problem with this is that those sellers aren't fully aware of the term nor the technicality of 1080i/p video, especially when demonstrated to potential customers. My advice: BE AWARE OF TERMS COMPANIES AND SALESPEOPLE USE JUST TO TURN A FAST BUCK. Not to say some salespeople are scamming customers, but a lot of them don't know what they're talking about (believe me, I've tested a few employees how much they know about video). That's why we're writing articles on these to educate new, upcoming filmmakers and various video technicians, and you, the consumer, so you aren't being back-handed into spending on something you didn't want. Besides that, we also want to educate in general, even if means folks like you not looking to buy a TV. (I just mentioned this since lots of electronics store get their employees to sometime hard-sell their TVs, depending how low their daily profits are.)

When it comes to videomaking, HD cameras and DSLR cameras only feature 1080p video using either a 30p frame rate (30 frames a second) or a 24p frame rate (24 frames a second). What about the whole 60 frames a second in progressive? Unavailable, unless you're looking to get a Varicam which is the price of a car. My feeling for 1080p at 60 frames, usually written as 1080p60, not being available is relatively to restrict consumers from using one video camera doing it all, while being able to sell new model cameras with new features every year (that may not be the reason, but I seem to notice this). Selling 1080p60 video to consumers mean no desire to purchase another camera. There are some video editors who can shoot 1080i video and able to deinterlace neatly while showing amazing slow-motion footage at a high resolution; Many others, though, not so much. Nevertheless, my other take as to why it's 1080p60 isn't available is the information and data the camera can take. Since progressive video takes up more hard drive space than interlaced video, then camera manufacturers feel the price of the camera would spike up higher than its MSRP since it requires more hardware to handle all that information on a camera. I don't know why but I have a hard time believing that; Perhaps I ought to sign up for a private, special tour to either Panasonic, Canon and/or Sony at their video camera department and see how a digital video camera is programmed and made. I, too, would love to know this.

When it comes to devices like HDTVs, it's all about careful reading and research on products because chances are good the salespeople will instantly say "oh, ALL the TVs we sell can show 1080p." Not so fast, sir. ALL TVs aren't created equally, as some TVs project movies at 1080p60 instead of 1080p at 24 frames a second, or 1080p24. The fact that some TVs can do this is baffling, yet cool. Hard to say since everything you watch seems like a "home movie" type of broadcast. Then again, there are TVs that interpret video broadcast as 1080p30 or 1080p24, making news broadcasts look like scenes from a film. Good or bad, depends how you like your video to look and the settings in the TV. All this is crucial to the diehard movie fans and even video gaming fans (yes, it's a big deal).

Cell phone/Smartphone video? Again, a lot of the companies say smartphones shoot at 1080p but they fail to mention the frame rate of what their phones shoot at. I have an old Samsung Galaxy phone and it shoots at 1080p30. This is where they make you believe that the video is shot at 1080p, but it's really shot at 30 frames a second, which is almost always in progressive video. Shocking isn't it? No worries, we're glad to let you know (LOTS of cell phone employees hard-selling phones barely know anything about video frame rates on cell phones, and if you don't believe me, ask one).

Overall, 1080i and 1080p are both high definition video showing great, excellent quality. However, being that it's 2017, video at 1080p is likely where you want to be. Now that you know the difference, you can browse and shop carefully without being hard-sold by someone who doesn't know the difference.

We will talk about frame rates on a future article.

Show off your videomaking skills over at Vimeo! Go ahead: go viral: