What Does High Definition Really Mean?

A recent experience with the Sony HDR-HC3 camcorder has led our columnist to a surprising discovery: He was wrong.

Richard Baguley
Thursday, May 25, 2006

I've been spending some quality time with the high-definition Sony HDR-HC3 over the past couple of weeks, and I think I might have to do something that we professional writers don't like to do: admit that I may have been wrong.

A few months ago I expressed my reservations about HD camcorders: I was concerned that they were too expensive, that it was too difficult to edit the video they produce, and that there were limited options for playing back the video. But Sony's HDR-HC3, which records high-definition video to MiniDV videotapes using a new format called HDV, has proven me wrong on a couple of counts.

The camcorder isn't cheap--with the $1300 it costs, you could buy four Canon MiniDV camcorders and still have money left over for accessories--but the ability to down-convert the video it captures makes it easy to edit and output to DVD while still retaining the high-definition original. And the slow-motion feature is fun as well: I've posted a few example videos on my blog.

High Definition = High Quality

So what does moving to a high-definition camcorder really mean in terms of quality? Let's look at an example: this image is a frame from a video shot with the HDR-HC3 in HDV mode (warning: it's a large 512KB image), while this is the same image in standard definition. Both images were saved as single frames in Adobe Premiere Pro 2.0 with deinterlacing enabled (which removes the jittery line effect you often see on captured video frames); the second was converted to standard definition using the HDR-HC3's down-conversion feature. The black bars in both images are added by Premiere--you don't see them in the video.

Here's another example: If you look at the photo of the cat's whiskers in this video still, you'll notice the extra resolution of the HDV frame. The 1080i HDV video that the HDR-HC3 records has much more resolution than the standard-definition image that has been down-converted: 1080i video is recorded at a resolution of 1080 by 1444 pixels, while standard-resolution video is 720 by 480 pixels.

What that means is that you can see much more detail. Look at the kitten's whiskers, for instance: In the standard-definition frame, the near-horizontal whiskers look jaggy, and the smaller ones can be barely seen. In the HDV frame, the whiskers are much more defined, and the jaggies on the near-horizontal ones are gone. This underlines the fact that if you shoot video in HDV, you get much more detail, which leads to much more realistic looking video. And, although the HDR-HC3 is not that much more expensive than a decent standard-definition camcorder, it records a lot more detail.

High-Definition Challenges

HDV does have its downsides, though. Look closely at this enlargement of the kitten's left eye: While the HDV frame is undeniably sharper, there is a slight, but noticeable pattern of square blocks on the left (it may be difficult to see in the small version on this page). This is caused by HDV's extra compression: In order to squeeze high-definition video onto the same tapes that standard-definition MiniDV camcorders use, the video has to be much more heavily compressed, and this leads to some blockiness. (Jim Feely has written a great article that goes into the specifics of this compression.)

But that's a pretty minor issue. Most people won't notice the blockiness. It only becomes a problem when you start to do compositing, which is where you replace a color with another image, so you can transport yourself from a plain green background to a tropical island. This blockiness means that the edges of area of color to be removed aren't clearly defined, which leads to a "halo" effect.

Editing HDV video is still a challenge. HDV uses a compression scheme in which only one out of every 15 frames is completely captured. With the 14 frames that follow it, only the differences between this and the previous frame are captured and stored on tape (video geeks call this interframe compression). This compression is generally not visible to the human eye, although you can sometimes see it if you are watching a video and the whole screen changes from one frame to the next, like a scene illuminated by a strobe light. Nonetheless, it makes editing HDV video much more complex for the computer, as it has to recalculate all 15 frames even if you edit only one.

I found that editing the HDR-HC3's HDV footage on a reasonably fast PC (a dual-core 2.8-GHz Pentium with 1GB of RAM) was significantly slower than editing standard-definition video, especially when things get complicated. It was particularly slow going when I worked on two HDV files that needed to be edited together, or when I needed to do some color correction, which changes the colors in the video and forces the computer to recalculate every frame. However, editing HDV is possible with a decent machine, just slower than working with standard-definition video.

So I may have to eat my own words; with camcorders like Sony's HDR-HC3, shooting high-definition video is becoming more and more realistic for home videographers. Right now, the resolution that most camcorders shoot at is called standard definition. But I'm thinking that in a few years, what's now called high definition may become the standard.
Richard Baguley still dreams in high definition; only now he's not sure what compression scheme his dreams are in, as he seldom remembers the good ones. He blogs about camcorders and video at CamcorderInfo.com, and you can contact him via e-mail.